power cables and wires technical manual 2010 edition

2010 Edition

Power Cables & WiresTechnical Manual

Through the initiative of:

International Copper Association – South East Asia

Institute of Integrated Electrical Engineers of the Philippines, Inc.

ISBN 978-971-93962-8-4

iii

PREFACE

This book, Power Cables and Wires Technical Manual, was written toaddress the need by consumers, specifiers, and purchasers to have aready reference guide in correctly specifying or ordering the appropriatecables and/or wires that will satisfy their particular requirements.Towards this purpose, a Cable/Wire Ordering Form, which appears inAnnex D, was developed so that the User will be able to indicate anditemize his needs and give all data and information necessary for theWires and Cable Manufacturer or Supplier to be able to supply the wireor cable that the User requires.

All components necessary for the construction of a cable or wire, fromthe conductor to the insulator, are each discussed in this manual so as toeducate or inform the reader of its fundamental use or purpose to thefinal product. Moreover, all the different types of material and theircharacteristics have been identified and explained in this manual tofurther elucidate the reader.

This publication was made possible through the initiative and support ofthe International Copper Association – South East Asia and the Instituteof Integrated Electrical Engineers of the Philippines, who developed,published and will propagate its use as reference.

Though conscientious efforts have been exerted to ensure the accuracy ofthe information in this manual, comments regarding errors and omissionsare most welcome and highly appreciated. All suggestions will bestudied and considered for inclusion in this manual’s next edition.

v

ACKNOWLEDGEMENT

This “Power Cables and Wires Technical Manual” was developed into aprinted publication through the collaborative efforts among professional,business and international organizations. In the course of the manual’sconceptualization, development and production, which spanned for morethan a year, several distinguished entities and individuals, havegenerously lent their utmost participation, assistance, knowledge,expertise and support towards the completion and publication of thismanual.

Special thanks are given to the Institute of Integrated ElectricalEngineers (IIEE) of the Philippines’ 2009 and 2010 Board of Governors,headed by their Presidents, Engrs. Arthur N. Escalante and Gregorio Y.Guevarra, respectively, for their insightful approval to engage theInstitute in this worthwhile project and sustaining the support until itscompletion. Of course, all of this would not have been possible withoutthe initiative and patronage of the International Copper Association –South East Asia, whose representative in the Philippines is Mr. JessieTodoc. Further, we want to recognize the critical support, knowledge andrelevant materials contributed by the following Wires and CablesCompanies; Columbia, Phelps Dodge, Sycwin and Philflex. Moreover,we would like to acknowledge the Bureau of Product Standards (BPS) ofthe Department of Trade and Industry (DTI) for the list of the existingPhilippine National Standards (PNS) on wires and cables.

Finally, eternal gratitude is given to the IIEE Adhoc Committee on Wiresand Cables, whose members are; Engr. Willington K. K. C. Tan, Engr.Cesar Gatpo, Ms. Maritess Templonuevo and Engr. Ricardo Lopez Jr.,who participated in the conceptualization and outline of the manual andwere instrumental in coming up with the Cable/Wire Ordering Form, andwhose indefatigable Chairman, Engr. Arthur A. Lopez, gave flesh to themanual. Special mention is given to Engr. Feldimir Siao of MERALCO,who conducted the review of the original manuscript and to Engr. WilsonYu for his valuable contributions.

Again, thank you very much.

vii

Table of Contents

Preface iiiAcknowledgement vTable of Contents viiIntroduction 1

1 Material Consideration 11.1 Resistance and Conductivity 21.2 Weight 31.3 Amapacity 41.4 Voltage Regulation 41.5 Short Circuit 41.6 Other Factors 4

2 Wire/Cable Manufacturing Process 52.1 Drawing 62.2 Annealing 62.3 Stranding 62.4 Bunching 62.5 Extrusion 7

3 Conductor Size 74 Stranding 10

4.1 Concentric Stranding 104.2 Compressed Stranding 114.3 Compact Stranding 114.4 Bunch Stranding 134.5 Rope Stranding 134.6 Sector Conductors 134.7 Segmental Conductors 134.8 Annular Conductors 14

5 Physical and Mechanical Properties 145.1 Conductor Properties 145.2 Tempers of Conductors 155.3 Conductor Direct Current (DC) Resistance 165.4 Conductor AC Resistance 195.5 Cables in Magnetic Metal Conduit 215.6 Resistance at Higher Frequency 22

viii

6 Insulation 226.1 Elastomers 236.2 Plastics 276.3 Insulation Resistance 33

7 Cable Design and Construction 358 Low Voltage Wires and Cables 36

8.1 Building Wires 398.2 Secondary and Service Cables 44

9 Medium and High Voltage Wires and Cables 499.1 Bare Conductors 499.2 Covered Conductors 539.3 Insulated Cables 57

10 Installation of Wires and Cables 6210.1 Maximum Allowable Tensions on Conductors 6210.2 Sidewall Pressure 6810.3 Bending Radius 69

11 Packaging 7212 Cable/Wire Application 7213 Cable Installation Method 7214 Color Coding 7215 Reference Standards 7316 Storage 7317 Available Cable Handling Equipment at Site 7518 Safeguards for Installing Wires and Cables in

Conduit 7518.1 Before Pulling Wire/Cable 7618.2 While Pulling Wire/Cable 7618.3 After Pulling Wire/Cable 76

19 Safeguard for Switchboard and Similar OpenWiring 76

20 Wire/Cable Ordering Form 77Annexes 79

Annex A 81Annex B 157Annex C 165Annex D 171

Bibliography 173

Power Cables & Wires Technical Manual

1

INTRODUCTION

One of the fundamental concerns of electrical engineering is thetransmission and distribution of electricity to its final utilization in amanner that is safe, efficient and economical. The choice of conductormaterial including size and design takes into consideration the operatingvoltage, ampacity, mechanical properties, type of installation and overallcost.

Electric wires and cables come in a wide variety of types andconstruction. It usually consists of a low resistance conductor toproperly transmit electric current. They can be classified in variousways depending on the factors being considered such as the material,degree of insulation, service, or voltage application.

The aim of this manual is to provide sufficient information on the typesof wires and cables available in the market including its intendedapplication in order for the reader to make an intelligent selection. Atthe end section of this manual, more detailed information are includedon the types and applications of wires and cables that an electricalpractitioner would generally need.

1. MATERIAL CONSIDERATIONS

There are several high conductivity metals that may be used asconductor. A conductor is a metallic material which allows electriccurrent to flow through it with less resistance. Table 1 ranked thesemetals according to resistivity at 20°C.

The best conductor material is silver but due to its high cost per unitweight and being one of the precious metals, it is not economical touse in the transmission and distribution of electricity. Comparatively,gold with its excellent corrosion resistance and lower resistivity thanaluminum is also a good conductor but, same as silver, is very costly.Thus, these metals i.e., silver and gold are only used in electricalapplications where low resistivity and corrosion resistance is of utmostimportance such as electrical contacts.


2

Copper with its inherent lower resistivity than aluminum is the preferredconductor on certain applications. It is malleable and ductile. Also, ithas a relatively higher tensile strength and easily soldered. However, itis more expensive and heavier than aluminum.

Table 1. Resistivity of Metals at 20°CMetal Ohm-mm2/m

Silver 1.59×10−8

Copper 1.68×10−8

Gold 2.44×10−8

Aluminium 2.82×10−8

Tungsten 5.60×10−8

Zinc 5.90×10−8

Nickel 6.99×10−8

Iron 1.0×10−7

Platinum 1.06×10−7

Tin 1.09×10−7

1.1 Resistance and Conductivity

Resistance is the opposition of an object to the passage of electriccurrent. For direct current, resistance is dependent on the materiallength, cross-sectional area and resistivity. The electrical resistanceof a conductor is inversely proportional to the cross-sectional area ordiameter of a conductor i.e., the larger the conductor the lessresistance it has to the flow of current. Conductivity, on the otherhand, is the complete opposite of resistance.

Compared with copper, aluminum has a number of technicaldisadvantages, all of which can be satisfactorily overcome tobenefit from its economic attraction. The advantage of its lowerdensity (about one-third that of copper) is partly offset by its lowconductivity of just 61% that of copper. Thus, an aluminumconductor must have a cross-sectional area about 1.6 times that ofcopper conductor to have the equivalent dc resistance. Suchdifference is approximately equal to two sizes higher (i.e., in AWG).


3

The grade and quality of copper is very important and the highconductivity copper used for electrical purposes comfortably exceedsthe 100% IACS (International Annealed Copper Standard)value. Conductivity is greatly influenced by impurities and bymechanical working. Consequently, the purity is of the order of99.99%, which nowadays is obtained by final electrolyticrefining. Fortunately, the mechanical strength of annealed copperwire is adequate for nearly all types of insulated cable. If any minorworking of the material occurs during conductor manufacture, e.g. incompacting to reduce the overall dimensions, allowance has to bemade for work hardening by increasing the copper volume tocompensate for the reduction in conductance. In an extreme case,such as the use of hard drawn copper for self-supporting overheadlines, this may amount to as much as 3%. Copper is invariably usedin the annealed condition except for the conductors of self-supporting overhead cables. Solid aluminum conductors are alsomainly in a soft condition but stranded aluminum conductors are ¾H (hard) to H.

1.2 Weight

Although aluminum has only about sixty-one percent (61%) of theconductivity of copper, its lightness makes long spans possible.Aluminum’s low density is one of its important advantages. Also, itsrelatively large diameter for a given conductivity reduces corona(the discharge of electricity from the wire when it has a highpotential), which contributes to the losses of the wire. This makesaluminum ideal for the transmission of high voltage power over longdistances. However, due to aluminum’s relatively low tensilestrength, the aluminum conductors are usually cabled around a steelsupport wire to improve the total tensile strength of the cable. Thisenables the relatively expensive transmission towers to be spacedfurther apart without the wire sagging too much. Electricaltransmission lines are the largest users of aluminum wire products. Infact, this is the one market in which aluminum has virtually nocompetition from other metals.

However, the relatively large size of aluminum for a givenconductance does not permit the economical use of an insulation


4

covering. Hence, low voltage household, office, and factoryelectric wires and cables are usually copper, which also does nothave the corrosion problems common to aluminum wires. Infact, copper has been unchallenged as a conductor for all types ofinsulated cables for well over seventy (70) years.

1.3 Ampacity

In general, current ratings of aluminum cables are about 78%-80% ofthose of copper cables of the same conductor size. An aluminumcable needs to be thicker than a copper cable in order to have thesame current carrying capacity.

1.4 Voltage Regulation

Reactance is negligible in all DC circuits and, in AC circuits withsmall conductors of sizes equal to or less than 60 mm2. Voltagedrops for a copper conductor and an aluminum conductor with 1.6times the cross-sectional area would be the same. However, in ACcircuits with large conductors, the resistance value is influenced byskin and proximity effect, and the reactance becomes important.

1.5 Short Circuit

Copper conductors have higher capabilities in short circuitoperations than aluminum conductors. However, for covered andinsulated conductors the thermal limitations of the materials whichform part of conductor should be considered before making suchcomparison.

1.6 Other Factors

Aluminum oxidizes rapidly when exposed to air, a thin corrosionresistance film having a high dielectric strength forms quickly. Thus,additional care must be taken when making connections. Material ofterminal connections should be taken into consideration since thiscould corrode the aluminum conductor. Also, when a combination ofcopper and aluminum conductors are to be connected together,special technique or connectors are required to have a reliableconnection.


5

Small strands of aluminum conductor have lower bending tolerancethat these are not used in generating stations, substations or portablecables. When there are space limitations, copper cables are thesuitable choice since aluminum cables are larger in size for the samecurrent carrying capacity.

Economics does play a vital consideration in the choice of conductorbut should include the other overlying cost involved to complete aninstallation.

2. WIRE/CABLE MANUFACTURING PROCESS

Copper and aluminum rods undergo several stages of processing beforethey become wires or cables. Below is a flowchart of the wire/cablemanufacturing process.

Figure 1: Wire Manufacturing Process

Bare solid harddrawn wire (1)

Bare stranded soft

drawn wire (1, 2 & 3)

Drawing

(1)

Stranding/

Bunching

(3)

Extrusion

(4)

Stranding/

Bunching

(3)

Extrusion

(4)

Insulated solid harddrawn wire (1 & 4)

Insulated stranded harddrawn wire (1, 3, 4)

Bare stranded harddrawn wire (1 & 3)

Annealing

(2)

Bare solid soft drawnwire (1 & 2) Insulated stranded soft

drawn wire (1, 2, 3 & 4)


6

2.1 Drawing

Drawing is the process of pulling the copper or aluminum rods orwires at normal temperature through a die to reduce the cross-sectional area in order to get the desired dimension. The wire isdeformed due to the tapering of the die and the force exerted duringpulling.

2.2 Annealing

Annealing is the process of “softening” the temper of the wire andimproving its cold working properties and machinability throughsustained heating at a pre-determined temperature followed bycooling at a defined rate. There are many ways of annealing a wire;the most common practices in annealing copper is the continuousstrand or resistance annealing wherein annealing is done bymeans of a machine placed between the final capstan of a drawingmachine and the spooler so that the wire is drawn, annealed andspooled in one operation.

2.3 Stranding

Stranding is the process where a number of hard or soft wires are laidtogether geometrically in such a way that each wire holds its place inthe strand all throughout the entire length. Generally, the number ofwires in a strand is 7, 19, 37, 61, and could reach up to 91, 127 or168 depending on the desired size or cross-sectional area ofthe stranded wire. The lay of multi-layered stranded wires are laidin opposite direction alternately in its succeeding lay with theoutermost generally being left-handed.

2.4 Bunching

Bunching is similar to the stranding process except that all individualwires are twisted uniformly in the same direction without regard forgeometrical arrangement. It provides a more flexibleconductor than a single strand. A number of bunches twisted togetherin the same direction and in uniform manner is called a compound


7

bunch. A number of bunches twisted together so that each bunch,except the central one, has a helical form of pre-determined lay ratiois a stranded bunch. A number of stranded bunches twisted togetherso that each stranded bunch, except the central one, has a helicalform of pre-determined ratio is called a compound strand bunch.

2.5 Extrusion

Extrusion is the process where an insulation material iscontinuously coated or applied around the conductor as it passesthrough a die in the head of an extruding machine. The insulationmaterial in form of pellets, dice and the likes (can be plastic, nylon,rubber, etc.) are placed in a hopper that is situated over a barrel inwhich a screw revolves. The insulation material softens as it feedsinside the heated extruder barrel then melted out over the corematerial through the screw which forces the material along the barreland compresses it at the same time to convert the material into fluidmass. The conductor emerges from the tip of the core with thematerial stream inside the extruder head and the insulation isformed to the required size and shape as the insulated conductorpasses through the die.

3. CONDUCTOR SIZES

Similar to most industries, standards for measuring conductor sizes hadbeen developed. A conductor’s size is usually specified based on theconductor’s cross-sectional area or its diameter. Conductor sizes areusually identified in accordance with either of the two predominant wiresizes, the American Wire Gauge (AWG) which is originally known asBrown and Sharpe gauge (B&S) or the Metric Wire Gauge (MWG),which is the international standard (SI or IEC).

The American Wire Gauge (AWG) is used predominantly in the UnitedStates of America (USA). The diameter of AWG No. 4/0 is 0.46 inch andthe diameter of the AWG No. 36 is 0.005 inch. The other 38 intermediatesizes are governed by a geometric progression with the followingformula:


8

Thus, the ratio of any diameter to the next size is 1.122932.

The conductor diameter will approximately double after the next 6 AWGsizes or it will be half after the next 6 lower sizes. For conductor sizeslarger than AWG No. 4/0, the size is expressed in circular mils which isan arbitrary cross-sectional area of the conductor. It is computed bymultiplying the individual wire diameter in inches by 1,000, squaring theresult, and multiplying by the number of wires. Usually expressed inkcmil (new term) or MCM (old term) which denotes thousand circularmils.

The metric wire gauge is used by most countries in the world. It uses theSI unit of square millimeters (mm2) to designate conductor size (i.e.,cross-sectional area). However, the designated metric wire sizes are notthe precise sizes. IEC standard allows a variation of up to 20% in theconductor area from the designated size.

In the Philippines, the wire sizes used are in metric but are, technically,based on AWG sizes. That is, the nearest metric equivalents to the cross-sectional area of the standard AWG sizes were adopted. Solid conductorsizes are specified according to its diameter (mm), while strandedconductor sizes are specified according to its cross-sectional area (mm2).Table 2 shows the conversion table of the standard AWG sizes to theirmetric equivalences.

A conductor’s size is directly proportional to its current carryingcapacity. Hence, the bigger the size of the conductor, the higher thecurrent it can carry or will be able to transmit for a given temperature.Annex A shows the current carrying capacity of the various sizes of bareand insulated, as well as, solid and stranded conductors according to theirapplication and method of installation.

For stranded conductors, the area is based on the sum of the cross-sectional area of the individual strands. Stranding of conductors providethe desired properties of flexibility, however, it also increases slightlythe overall diameter because of the small gaps between the strands.Hence, a stranded conductor will always have a slightly larger overalldiameter than a solid conductor with the same size or gauge.


9

Table 2 - Conversion Table(Nearest AWG/kcmil to mm2)

PEC (PNS) ASTM Metric (IEC)mm2 (mm. dia.) AWG/kcmil

(mm. dia.)mm2 (mm. dia.)

SOLID(1.6 mm)(2.0 mm)(2.6 mm)(3.2 mm)

1412108

(1.63mm)(2.05 mm)(2.59 mm)(3.26 mm)

STRANDED2.03.55.58.0

(7 x 0.6 mm)(7 x 0.8 mm)(7 x 1.0 mm)(7 x 1.2 mm)

1412108

(7 x 0.615 mm)(7 x 0.775 mm)(7 x 0.978 mm)(7 x 1.23 mm)

2.54.06.010

(7 x 0.67 mm)(7 x 0.85 mm)(7 x 1.04 mm)(7 x 1.35 mm)

14223038

(7 x 1.6 mm)(7 x 2.0 mm)(7 x 2.3 mm)(19 x 2.3 mm)

6421

(7 x 1.56 mm)(7 x 1.96 mm)(7 x 2.47 mm)(19 x 1.69 mm)

162535

(7 x 1.71 mm)(7 x 2.13 mm)(7 x 2.52 mm)

506080100

(19 x 1.8 mm)(19 x 2.0 mm)(19 x 2.3 mm)(19 x 2.6 mm)

1/02/03/04/0

(19 x 1.89 mm)(19 x 2.13 mm)(19 x 2.39 mm)(19 x 2.68 mm)

50

7095

(19 x 1.8 mm)

(19 x 2.17 mm)(19 x 2.52 mm)

125150

200

(37 x 2.1 mm)(37 x 2.3 mm)

(37 x 2.6 mm)

250300350400

(37 x 2.09 mm)(37 x 2.29 mm)(37 x 2.47 mm)(37 x 2.64 mm)

120150

185

(37 x 2.03 mm)(37 x 2.3 mm)

(37 x 2.52 mm)

250325400

(61 x 2.3 mm)(61 x 2.6 mm)(61 x 2.9 mm)

450500600750

(37 x 2.8 mm)(37 x 2.95 mm)(61 x 2.52 mm)(61 x 2.82 mm)

240300400

(61 x 2.44 mm)(61 x 2.5 mm)(61 x 2.9 mm)

500 (61 x 3.2 mm) 1000 (61 x 3.25 mm) 500 (61 x 3.2 mm)


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Left hand lay direction

Concentric Stranding

4. STRANDING

The conductor material may be either solid or stranded. A solidconductor is a single, solid strand of conductor for the whole length ofthe wire, while a stranded conductor is composed of several strands ofconductor concentrically wounded together over the whole length of thewire/cable. For the same cross-sectional area of a conductor, there arediameter differences between solid and various types of strandedconductors. This is an important consideration in the selection ofconnectors and in the methods of splicing and terminating.

Large sizes of solid conductors are too rigid for many applications thatthe solution would be to have smaller wires and strand them together toform the conductor. There are several ways of stranding the wirestogether which is dependent of the type and temper of the metal used.The following subsections will discuss the most commonly usedstranding for copper conductors.

4.1 Concentric Stranding

This consists of a central wire or core surroundedby one or more layer of hellically applied wires.Each layer is applied in a direction opposite tothe layer underneath, except for unilayconstruction wherein the layers are applied in thesame lay direction. Lay length is the distancerequired to make one complete revolution of astrand around the central conductor. Lay lengthrequirement based on the American Society ofTesting Materials (ASTM) standard is for neither it to be not lessthan 8 times nor more than 16 times the overall diameter of thatlayer.

For power cables, thestandard stranding is ClassB. The outermost layershould be of a left hand laywhich means that when yougo along the axis of the conductor the outermost layer of strandsshould roll towards the left as they recede from the observer. More


11

Compact Stranding

Compressed Stranding

flexibility is obtained by using small strands and increasing thenumber of wires in the conductor. Class C has one more layer thanClass B, Class D has one more layer than Class C and so on. Theclass designation goes up to M (those normally used for weldingcables).

4.2 Compressed Stranding

This construction slightly deforms the layersto allow the layer being applied to closetightly. The diameter of the conductor can bereduced by up to 3% of the equivalentconcentric strand. There is no, however,reduction in the conductor area.

4.3 Compact Stranding

This is similar to compressed stranding exceptthat additional forming is done to reduce theconductor diameter typically by 9% less thanits equivalent concentric stranded conductor.The resulting diameter is a near solidconductor.


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Table 3 - Diameter for Stranded Copper and Aluminum Conductors

ConductorSize

Nominal Diameters (mm)

Concentric Stranded Compressed CompactClass B Class C

AWG8 3.708 3.759 3.581 3.4046 4.674 4.742 4.521 4.2934 5.893 5.944 5.715 5.4103 6.604 6.680 6.401 6.0452 7.417 7.518 7.188 6.8071 8.433 8.458 8.179 7.5951/0 9.474 9.500 9.169 8.5342/0 10.643 10.668 10.312 9.5503/0 11.938 11.963 11.582 10.7444/0 13.411 13.437 13.005 12.065kcmil250 14.605 14.630 14.173 13.208300 16.002 16.027 15.519 14.478350 17.297 17.297 16.789 15.646400 18.491 18.517 17.932 16.739450 19.609 19.634 19.025 17.780500 20.650 20.701 20.041 18.694550 21.717 21.717 21.057 19.685600 22.682 22.682 21.996 20.650650 23.597 23.622 22.885 21.463

700 24.486 24.511 23.749 22.276

750 25.349 25.375 24.587 23.063

800 26.187 26.213 25.400 23.825

900 27.762 27.762 26.949 25.375

1000 29.261 29.286 28.372 26.924

Notes:1. Compressed and compact nominal diameters are based on concentric lay

stranded Class B construction.2. The above diameters are based on ASTM specifications (converted into SI or

metric units).


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Rope Stranding

Bunch Stranding

Segmental Conductor

Sector Conductor

4.4 Bunch Stranding

In this construction the conductor strands aretwisted together in the same direction withoutany regard to the geometric arrangement.Commonly used when very flexible wire isrequired for small conductor sizes, such asportable cables.

4.5 Rope Stranding

This is a combination of the concentricconductor and a bunch stranded conductor.The complete conductor is composed of anumber of groups of bunched or concentricstranded conductors assembled concentricallytogether.

4.6 Sector Conductors

The cross-section of these conductors isapproximately the shape of a circle’s sector. Amulti-conductor insulated cable with threesector conductor cables have three 120°segments that combine to form a circle as afinished cable. This cable have smallerdiameter than the cable with round conductors.Also, these cables have lower ac resistance due to a reduction of theproximity effect.

4.7 Segmental Conductors

A segmental conductor is a round, strandedconductor composed of three or four sectorsslightly insulated from one another. Thisconstruction has the advantage of lower a-cresistance due to less skin effect.


14

Annular Conductor

4.8 Annular Conductors

The round stranded conductors are laid arounda suitable core. The core is usually madewholly or mostly of non-conducting material.This construction has the advantage of lowertotal a-c resistance for a given cross-sectionalarea of conducting material by eliminating thegreater skin effect at the center.

5. PHYSICAL AND MECHANICAL PROPERTIES

Although high conductivity is an important feature of a good conductor,there are other factors that must be considered. Silver maybe the mostconductive material but high cost and lack of physical strength makes itinappropriate for commercial usage as wire and cable. Thus, thedominant metals used for wires and cables are copper and aluminum.

5.1 Conductor Properties

Copper and aluminum has its own advantageous anddisadvantageous characteristics that affect its use under varyingcircumstances. A comparison o f s o m e o f the characteristics ofcopper and aluminum is given in Table 4.


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Table 4: Comparative Characteristics of Copper and Aluminum

CHARACTERISTICS (20o

C) COPPER ALUMINUM

Ultimate Tensile Strength (MN/m2)soft temper¾ H to H

225385

70-90125-205

Hardness (DPHN)soft¾ H to H

50115

20-2530-40

Weight for the same conductivity (kg.) 45.4 21.8

Cross section for the same conductivity(mm2)

0.05 0.08

Weight Resistivity(Ohms-g/m2) 0.153280 0.076149

Volume Resistivity (Ohms- mm2/m) 0.017241 0.028172

Temperature Coefficient of Resistance (o

C) 0.00393 0.00404

Thermal Conductivity (W/cm °C) 3.8 2.4

Coefficient of Thermal Expansion per °C 17.0 x 10-6 23.0 x 10-6

Density (kg/m3) 8890 2703

Melting Point (o

C) 1,083 659

Modulus of Elasticity (MN/m2) 26 14

Stress Fatigue Endurance Limit(approximate) (MN/m2)

+/- 65 +/- 40

5.2 Tempers of Conductors

Drawing copper or aluminum rods into a wire results in thehardening of the finished wire. This causes a soft temper rod tobecome a hard temper wire. It may be desirable to utilize aconductor of softer temper in cable construction. This can beachieved through an annealing process during or after wire drawingor stranding.

Annealing consists of heating the conductor to elevatedtemperatures for specific time periods. This is usually done in anoven or by continuous resistance annealing at the drawingmachine.

Copper can be provided in three (3) tempers based on ASTMstandards. These tempers are soft or annealed, medium-hard andhard-drawn. Soft or annealed is the most often used temper for


16

insulated conductors due to its flexibility. Medium hard-drawn andhard-drawn tempers are most often used in overhead applications dueto their higher breaking strengths.

On the other hand, aluminum can be provided in five (5) tempersbased on ASTM standards as shown in the Table 5, below. Notethat the overlapping values showing the same conductor maymeet the temper requirements of two classifications.

Table 5 – Tensile Strength of the Different Temper Classificationsof Aluminum

Classifications of 1350 Aluminum Tensile Strength(in kg/cm2)

Full Soft (H-0) 597.6 to 984.3¼ Hard (H-12 or H-22) 843.7 to 1195.3½ Hard (H-14 or H-24) 1054.7 to 1406.2¾ Hard (H-16 or H-26) 1195.3 to 1546.8

Full Hard (H-19) 1582 to 2039

Three quarters and full hard are the most common tempers usedwith 1350 aluminum for insulated conductors. Full hard drawntemper is most often used in overhead applications due its higherbreaking strengths.

5.3 Conductor Direct Current (DC) ResistanceThe DC resistance (Rdc) of a conductor of uniform cross section can becomputed as:

where, l = length of the conductor, meters (m)A= cross-sectional area of the conductor, square meters

(m2)ρ = (Greek: rho) electrical resistivity (also called specific

electrical resistance) of the material, ohm-meters (Ω-m)ρ for copper is 1.678 x 10-8 Ω-m at 20°Cρ for aluminum is 2.65 x 10-8 Ω-m at 20°C


17

Since resistance is temperature dependent, conversion of a givenresistance at a specified temperature to another is given by theseformulas:

Copper: Aluminum:

where, R2 = conductor resistance at temperature T2 in °CR1 = conductor resistance at temperature T1 in °C

These formulas are based on the resistance coefficient of copperhaving 100% conductivity and aluminum having 61.2% conductivitybased on International Annealed Copper Standard (IACS).


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Table 6 - DC Resistance in Ohms Per Kilometer at 25oC

Size Solid Concentric Lay StrandedAWG orkcmil

Copper*Uncoated

Aluminum Copper*UncoatedClass B, C

AluminumClass B, C

8643211/02/03/04/0250300350400450500550600650700750800

2.0991.3220.8300.6590.5520.4130.3280.2600.2070.164————————————

3.4442.1681.3611.0790.8560.6790.5380.4260.3380.2690.2280.1900.1620.1420.1260.114——————

2.1391.3480.8460.6720.5310.4230.3350.2660.2110.1670.1410.1180.1010.0880.0790.0710.0640.0590.0540.0510.0470.044

3.5102.2141.3911.1020.8720.6920.5510.4360.3440.2740.2320.1940.1660.1450.1290.1160.1050.0970.0890.0830.0770.072900 — — 0.039 0.064

1000 — — 0.035 0.058*Uncoated – without tin or lead covering

The resistance values of the different conductor sizes inTable 6 are applicable only when Direct Current (DC) isflowing through the conductors.


19

5.4 Conductor AC Resistance

When Alternating Current (AC), at sixty Hertz (60 Hz), is flowingthrough said conductors, the DC resistance values have to bemultiplied with the corresponding correction factor (Table 7) toobtain the AC resistance values of the different conductor sizes.

Table 7 - Multiplying Factors for Converting D.C. to A.C.Resistance

Size

Multiplying FactorFor Non-metallic SheathedCables in Air or Non-metallic Conduit

For Metallic SheathedCables or all Cables inMetallic Raceways

Copper Aluminum Copper AluminumUp to 32100000000002503003504005006007007508001000

1.0001.0001.0001.0011.0011.0021.0041.0051.0061.0091.0111.0181.0251.0341.0391.0441.067

1.0001.0001.0001.0001.0011.0011.0021.0021.0031.0041.0051.0071.0101.0131.0151.0171.026

1.001.011.011.021.031.041.051.061.071.081.101.131.161.191.211.221.30

1.001.001.001.001.001.011.011.021.021.031.041.061.081.111.121.141.19

1250150017502000

1.1021.1421.1851.233

1.0401.0581.0791.100

1.411.531.671.82

1.271.361.461.56


20

If a conductor is carrying high alternating current, the distribution ofthe current is not evenly distributed throughout the cross-sectionof the conductor. This is due to two independent effects known as“Skin Effect” and “Proximity Effect”.

5.4.1 Skin effect

Skin Effect is a natural phenomena in wires wherein alternatingelectric current (AC) tends to distribute itself within a conductorso that the current density near the surface of the conductor isgreater than at its core. That is, the electric current tends to flowat the “skin” of the conductor, at an average depth called theskin depth. The skin effect causes the effective resistance of theconductor to increase with the frequency of the current. Thehigher the frequency the smaller is the skin depth. The skineffect is due to eddy currents set up by the AC current. Themagnitude of the skin effect is influenced by the frequency, thesize of the conductor, the amount of current flowing, and thediameter of the conductor.

Skin depth varies as the inverse square root of the conductivityof the conductor material. This means that better conductorshave a reduced skin depth. The overall resistance of the betterconductor material is lower even though the skin depth is less.This tends to reduce the difference in high frequency resistancebetween metals of different conductivity. At 60 Hertz (Hz) incopper, skin depth is about a centimeter. At higher frequencies,skin depth is much smaller.

Likewise, skin depth also varies as the inverse square root of thepermeability (which is a macroscopic material property thatrelates or is the ratio of the magnetic flux density to the strengthof the magnetic field that induces it) of the conductor material.In the case of iron, its conductivity is about 1/7 that of copper.Its permeability, however, is about 10,000 times greater. Theskin depth of iron is about 1/38 that of copper or about220 micrometers at 60 Hz. Iron wire, therefore, is worthless as aconductor at power line frequencies.

Methods to minimize skin effect include using specially woven(braided) cable/wire and using hollow pipe-shaped conductors.


21

5.4.2 Proximity Effect

The Proximity Effect is associated with the magnetic fields oftwo conductors, which are close together. If each carries acurrent in the same direction, the halves of the conductor inclose proximity are cut by more magnetic flux than the remotehalves. Consequently, the current distribution is not eventhroughout the cross-section, a greater proportion being carriedby the remote halves. If the currents are in opposite direction,the halves in closer proximity carry the greater density ofcurrent. In both cases, the overall effect results in an increase inthe effective resistance of the conductor. The proximity effectdecreases with the increase in the spacing between cables.

Skin and Proximity Effects can be ignored with smallconductors carrying low currents. They become increasinglysignificant with larger conductors and it is often desirable fortechnical and economic reasons to design theconductors/cables to minimize them. Values of skin andproximity effects can be computed based on the formulasprovided by IEC 60287-1-1.

5.5 Cables in Magnetic Metal Conduit

Due to excessive hysteresis and eddy currents, all phases of an ACcircuit should be installed in the same magnetic metal conduits.Never install individual phases in separate metal conduits under anycircumstances due to the high inductance of such installation. Also,separate phases should not pass through magnetic structures sinceoverheating would occur in such situation. All phases should passthrough a magnetic enclosure together in order that there will be acancellation of the resultant magnetic field. However, the proximityof the magnetic material will increase the skin and proximity effect.Thus, there can be significant losses when large conductors are nearmagnetic materials.

Large cable sizes from 100 mm2 or larger should not be installed inseparate non-magnetic metal conduit due to the high circulatingcurrents in the conduit. The ampacity of the cables should be de-rated in such condition.


22

5.6 Resistance at Higher Frequency

Ampacity and resistance of cables to be operated at frequencieshigher than 60 hertz should be corrected. The inductive reactanceincreases at high frequencies which may affect the voltage drop.Insulated conductors should not be installed in metallic conduits orrun close to magnetic materials.

The correction factor for the resistance at frequencies other than 60hertz is provided as follows:

where, f = frequency in hertzRdc = conductor DC resistance at operating temperature

in Ohm/1000 ft

6. INSULATION

Insulation is that part of the cable or wire which is relied upon toinsulate the conductor from other conductors or conducting parts orfrom ground. Insulating materials are usually classified according to thetemperature they are able to withstand. The applied insulation mustperform adequately in the specified temperature range and its dielectricstrength should be sufficient to sustain the electrical stresses.

There are many insulating materials used in producing the variouscables to deliver electric power depending on their temperature limits,such as cotton, silk, paper, mica, glass fiber, asbestos, rubber, siliconeelastomer, etc. Sometimes insulating materials, such as cotton, silk andpaper are impregnated or coated with a dielectric liquid, such as oil, toenhance their insulating capabilities.


23

Cable insulation should have the following properties:

1. High Dielectric strength2. Low Dielectric Constant3. Good mechanical capability4. Resistance to ageing5. High temperature withstandability

In recent times, synthetic polymers have replaced natural materials suchas paper, mineral oil and natural rubber for the insulation of wires/cablesand for the over-sheathing of cables. The range of polymers available isextensive and variations in chemical composition enable specificmechanical, electrical and thermal properties to be obtained. Whereappropriate, these properties may be further modified by the addition ofspecific fillers, plasticizers, softness extenders, colorants, antioxidantsand many other ingredients.

In the cable industry, the term polymeric material is taken to signifypolymers which are rubbers or plastics. Rubbers are considered to besolid materials, with elastic properties, which are made from latexderived from living plants or synthetically and used in themanufacture of rubber products. Plastics, on the other hand, arematerials based on synthetic or modified natural polymers which atsome stage of manufacture can be formed to shape by flow, aided inmany cases by heat and pressure. These two material groups are thedominant means of insulating wires and cables.

6.1 Elastomers

An elastomer is a material which returns rapidly to approximately itsinitial shape after substantial deformation at room temperature by aweak stress and release of that stress. In cable technology, the terms“rubber” and “elastomer” are used synonymously andinterchangeably, although “rubber” to some implies “natural rubber”.

Elastomeric materials are used for insulation and sheaths. They areapplied mainly where the product has to be particularly flexible. Awide range of elastomers are nowadays available to the cableindustry. This makes possible the manufacture of compoundswith specific properties, such as abrasion and oil resistance,


24

weather and heat resistance, and flame resistance, combined withgood electrical and mechanical characteristics.

The classical elastomeric material, natural rubber (NR), was thefirst insulation to be used in the manufacture of electric cable. Its useas an insulation has been declining in recent years. Rubber gave wayto other insulating materials like impregnated paper, PVC, XLPE,etc. Rubber, though, is still considered the preferredinsulation for flexible cables and cables where very small bendingdiameter is desired. Rubbers for cable insulation and sheath,whether natural or synthetic, are normally crosslinked.

In place of rubber, synthetic elastomers produced by the co-polymerization of ethylene and propylene, are constantly findingnew areas of application in cable engineering. These co-polymers are generally known as Ethylene-propylene rubber (EPR).Because of its superior performance, with suitability for continuousoperation at 90°C, EPR has gradually displaced butyl rubber forinsulation and is now being considered as over sheath material forcable.

Polychloroprene (PCP), otherwise known as neoprene, was the firstcommercial synthetic rubber. It has rarely been used by itself forinsulation but is often used blended with natural rubber. Its majoruse is as a very tough flexible sheathing material.Polychloroprene compounds have good abrasion and tearresistance together with good resistance to swelling and to chemicalattack by a wide range of natural oils and aliphatic hydrocarbons.They do not normally support combustion

Chlorosulphonated polyethylene rubber (CSP, CSM) havesuperior electrical properties to compounds based on PCP and areparticularly advantageous for insulation and sheathing which isrequired to be oil resistant. CSP also has good resistance to ozoneand weathering. When blended with EVA or EPR and filled with asuitable carbon black, CSP compounds provide a strippabledielectric screening material for XLPE and EPR cables in the 10-30kV range.


25

Acrylonitrile-butadiene rubber (NBR/PVC blends) is theproduct of the co-polymerization of acrylonitrile with butadiene.This range of polymers is characterized by good oil resistance. Theaddition of PVC improves resistance to ozone, weathering andabrasion. By suitable choice of plasticizers, improvedprocessability and flame retardance are also obtained. Thesematerials are used solely for sheathing.

Fluorocarbon rubbers find application for sheathing where verygood resistance to oils is required at high temperatures. The bestknown material is a copolymer of vinylidene fluoride andhexafluoropropylene (Viton).

Ethylene-acrylic elastomers (EMA) are heat- and oil-resistantnon-halogen synthetic rubbers which can be compounded toresist ignition in the presence of flame and have low smokegeneration when burned. They are suitable for servicetemperatures of 40-170°C.

Silicone rubber is a material made from silicon and oxygen noted forhigh heat resistance. This is very soft thermoset insulation extremelyflexible and fire resistant. It has excellent electrical properties plusozone and resistance, low moisture absorption, weather resistance,and radiation resistance. It typically has low mechanical strength andpoor scratch resistance.

Table 8 shows the properties of thermoset insulation and jacketmaterials


26

Table 8: Properties of Thermoset Insulation and Jacket Materials

INSULATION ORJACKETMATERIAL

ST

YR

EN

EB

UT

AD

IEN

ER

UB

BE

R(S

BR

)

NA

TU

RA

LR

UB

BE

R

SY

NT

HE

TIC

RU

BB

ER

PO

LY

BU

TA

DIE

NE

NE

OP

RE

NE

HY

PA

LO

NC

HL

OR

OS

UL

FO

NA

TE

DP

OL

YE

TH

YL

EN

E(C

SP

E)

NIT

RIL

EO

RR

UB

BE

RB

UT

AD

IEN

EN

ITR

ILE

(NB

R)

NIT

RIL

E//

PO

LY

CH

LO

RID

E(N

BR

/PV

C)

ET

HY

LE

NE

PR

OP

YL

EN

ER

UB

BE

R(E

PR

)

CR

OS

S-L

INK

ED

PO

LY

ET

HY

LE

NE

(XL

PE

)

CH

LO

RIN

AT

ED

PO

LY

ET

HY

LE

NE

(CP

E)

SIL

ICO

NE

RU

BB

ER

Oxidation Resistance F F G G G E F E E E E E

Heat Resistance F-G F F F G E G G E G E O

Oil Resistance P P P P G G G-E G P G G-E F-G

Low Temp. Flexibility F-G G E E F-G F F F G-E O F O

Weather, SunResistance

F F F F G E F-G G E G E O

Ozone Resistance P P P P G E P G E G G-E O

Abrasion Resistance G-E E E E G-E G G-E E G F-G G-E P

Electrical Properties E E E E P G P F E E F-G O

Flame Resistance P P P P G G P G P P G O

Nuclear RadiationResistance

F-G F-G F-G P F-G E F-G P G E G E

Water Resistance G-E G-E E E E E G-E E G-E G-E G-E G-E

Acid Resistance F-G F-G F-G F-G G E G G G-E G-E E F-G

Alkali Resistance F-G F-G F-G F-G G E F-G G G-E G-E E F-G

Gasoline, Kerosene,Etc. (AliphaticHydrocarbons)Resistance

P P P P G F E G-E P F F P-F

Benzol, Toluol, Etc.(AromaticHydrocarbons)Resistance

P P P P P-F F G G F F F P

Degreaser Solvents(HalogenatedHydrocarbons)Resistance

P P P P P P-F P G P F P P-G

Alcohol Resistance F G G F-G F G E G P E G-E G

P = Poor F = Fair G = Good E = Excellent O = Outstanding


27

6.2 Plastics

Plastics may be further divided into thermoplastics and thermosets.A thermoplastic is a material in which the molecules are heldtogether by physical rather than chemical bonds. This means thatonce the material is above its melting point it can flow. The processis reversible and upon cooling the material hardens. The moleculesin a thermoset are held together by chemical bonds which are noteasily broken. This means that on heating the polymer does notsoften sufficiently to be reshaped. Typical examples are crosslinkedpolyethylene (XLPE) and elastomers. Unlike thermoplastics,thermosets are insoluble and infusible, i.e. it will not fuse together.Many thermoplastics may be converted to thermosets by appropriatetreatment to induce “crosslinking”, e.g. by the addition of a suitablechemical crosslinking agent or by irradiation.

6.2.1 Thermoplastics

Thermoplastics are the most popular insulating materials for lowvoltage wires and cables due to lower in cost and lighter weight.Some of the most popularly used are discuss below.

Polyvinyl Chloride (PVC)

Polyvinyl Chloride, also called vinyl, is a thermoplastic materialintroduced in 1932. Since then, PVC has become the standardinsulation used on wires and cables rated at 1000 volts or less.Vinyl compounds are mechanical mixtures of PVC resin,plasticizers, fillers, stabilizers, and modifiers. The quantity andtype of each ingredient determines the final properties of thecompound.

PVC compounds can be formatted to provide a broad range ofproperties from the standpoint of electrical, physical andchemical characteristics. However, in achieving superiority inone property, the other properties are usually compromised. Thegoal, therefore, is to optimize the critical property or propertieswithout allowing secondary properties to fall below acceptablelevels.


28

PVC has a high dielectric strength and good insulationresistance. It is inherently tough and resistant to flame, moistureand abrasion. Resistance to ozone, acids, alkalis, alcohols, andmost solvents are also adequate. PVC compounds can be maderesistant to oils and gasoline. Its temperature ratings range from60°C to 105°C based on basic formulation.

Disadvantage of PVC include a relatively high dielectricconstant and dissipation factor. Plasticizer loss throughevaporation or leeching eventually may cause embrittlement andcracking. PVC compounds significantly stiffen as temperaturesdecline, and are not generally recommended for uses whichrequire flexing below -10°C. However, special formulationshave been developed which will allow flexing to up to -40°C.

Polyethylene

Polyethylene is a long chain hydrocarbon thermoplastic materialwhich is produced by the polymerization of ethylene gas underhigh or low pressure. PE is popular because of its relatively lowprice, processability, resistance to chemicals and moisture,electrical properties, and low temperature flexibility. PE isproduced in low, linear low, medium, and high densities. As thedensity increases, so does the hardness, yield strength, stiffness,heat, and chemical resistance.

PE’s electrical properties are excellent. Typical values for anatural, unfilled insulation compound include a volumeresistivity of greater than 1016 ohm-cm, a dielectric constant of2.3, a dissipation factor of 0.0002, and a water absorption of lessthan 0.1%. However, if PE cables are exposed to sunlight,carbon black or a suitable inhibitor is added to screen out ultra-violet (UV) radiation. UV radiation can degrade both thephysical and electrical properties of the insulation.

A disadvantage of PE is that, like most plastics, it is susceptibleto degradation from treeing when it is subjected, to highelectrical stress. Treeing is a phenomenon occurring within thecable, when subjected to medium to high voltages, wherein the


29

breakdown of the insulation due to ionization occurs through theformation of carbonaceous “fronds” on the insulation due to thepresence of water or voids during the extrusion of the insulationmaterial at cable construction. The carbonaceous paths start at analmost imperceptible carbon core, generally at the conductorsurface, and gradually spread outwards through the insulation,increasing in width and complexity as progression takes place.Corona discharges and treeing may lead to premature cablefailure.

Polypropylene

Polypropylene is a thermoplastic insulating compound withcharacteristics similar to high density polyethylene withimproved heat resistance, tensile strength, and abrasionresistance. Polypropylene also has a lower specific gravity andlower dielectric constant than polyethylene. Polypropylene hasgood impact strength, low moisture absorption, excellentchemical resistance, high creepage resistance, and is useful inhigh frequency applications. It retains these excellent propertiesin cellular constructions. Typically, it is harder thanpolyethylene. This makes it suitable for thin wall insulations.

Polyurethane

Polyurethane is a broad class of polymers noted for goodabrasion and solvent resistance which can be in solid or cellularform. This thermoplastic material is used primarily as a cablejacket material. It has excellent oxidation, oil, and ozoneresistance. Some formulations also have good flame resistance. Itis a hard material with excellent abrasion resistance. It hasoutstanding "memory" properties, making it an ideal jacketmaterial for retractile cords.

Teflon

Teflon is an extremely reliable high temperature, low voltageinsulation often chosen for its non-aging characteristics, thinwall insulating capability, resistance to chemicals and abrasionresistance. Also, important is its low dielectric constant and low


30

power factor. There are two (2) types-Tetrafluorethylene TFE,and Fluorinatedethylenepropylene FEP. Teflon is not damagedby normal soldering operations. It is not suitable when subjectedto nuclear radiation and does not have good high voltagecharacteristics.TFE insulation in tape form (often fused) iswidely used and can be provided in very long lengths. Type FEPcan be extruded in long, continuous lengths and is readily colorcoded for use in control and instrumentation cables.

Tefzel

Tefzel ETFE is a melt processible fluorocarbon thermoplasticcombining many of the desirable properties of Teflon and Kynarrated at 150°C. Mechanically it is tough with excellent flex life,impact, cut-through, abrasion and weather resistant. Electricallyit is an excellent low loss dielectric and has outstanding electricalproperties. It is inert to most solvents and chemicals and ishydrolytically stable. Like irradiated polyethylene, it hasexcellent resistance to high-energy radiation.

Table 9 shows the properties of thermoplastic insulation andjacket materials.


31

Table 9: Properties of Thermoplastic Insulation and Jacket Materials

INSULATION ORJACKETMATERIAL

PO

LY

VIN

YL

CH

LO

RID

E(P

VC

)

LO

W-D

EN

SIT

YP

OL

YT

HY

LE

NE

CE

LL

UL

AR

PO

LY

TH

YL

EN

E

HIG

H-D

EN

SIT

YP

OL

YT

HY

LE

NE

PO

LY

PR

OP

YL

EN

E

CE

LL

UL

AR

PO

LY

PR

OP

YL

EN

E

PO

LY

UT

ET

HA

NE

NY

LO

N

CP

E

TE

FL

ON

(FE

P)

TE

FL

ON

(TP

E)

TE

FZ

EL

(ET

FE

)

Oxidation Resistance E E E E E E E E E O O E

Heat Resistance G-E G G E E E G E E O O E

Oil Resistance F G-E G G-E F F E E E O E-O E

Low Temp.Flexibility

P-G E E E P P G G E O O E

Weather, SunResistance

G-E E E E E E G E E O O E

Ozone Resistance E E E E E E E E E E O E

Abrasion Resistance F-G G F E F-G F-G O E E-O E O E

Electrical Properties F-G E E E E E P P E E E E

Flame Resistance E P P P P P P P E O E G

Nuclear RadiationResistance

F G-E G G-E F F G F-G O P-G P E

Water Resistance F-G E E E E E P-G P-F O E E E

Acid Resistance G-E G-E G-E E E E F P-E E E E E

Alkali Resistance G-E G-E G-E E E E F E E E E E

Gasoline, Kerosene,Etc. (AliphaticHydrocarbons)Resistance

P G-E G G-E P-F P P-G G E E E E

Benzol, Toluol, Etc.(AromaticHydrocarbons)Resistance

P-F P P P P-F P P-G G G-E E E E

Degreaser Solvents(HalogenatedHydrocarbons)Resistance

P-F G G G P P P-G G E E E E

Alcohol Resistance G-E E E E E E P-G P E E E E

P = Poor F = Fair G = Good E = Excellent O = Outstanding


32

6.2.2 Thermosetting

Most plastic insulations are thermoplastics, except forcrosslinked polyethylene which is the predominant insulation formedium and high voltage cables. Other thermosetting insulationmaterials are elastomers.

Crosslinked Polyethylene (XLPE)

Crosslinked polyethylene is a thermoset material produced bycompounding polyethylene or a copolymer of ethylene and vinylacetate (EVA) with a crosslinking agent, usually an organicperoxide. The individual molecules of polyethylene join togetherduring a curing process to form an interconnected network. Theterms “cure” and “vulcanize” are often similarly used todesignate crosslinking.

While the use of peroxide as the crosslinking agent means thatonly low density polyethylene can operate at higher temperaturesthan cables produced with thermoplastic or non-crosslinkedpolyethylene.

Crosslinking also significantly improves the physical propertiesof the polyethylene. Additives tend to reduce the electricalproperties of the insulation. This is the reason that EVAcopolymer is used only for low voltage applications. For mediumvoltage applications, crosslinked polyethylene fares well becausethe dielectric strength of the unfilled crosslinked polyethylene isabout the same as that of thermoplastic polyethylene. Impulsestrengths of 2700 V/mil are common.

For low voltage applications, the addition of fillers, in particular,medium thermal carbon black, provides increases in tensilestrength and hardness. It also provides the necessary ultravioletprotection for outdoor applications without the use of a jacket.The EVA copolymer is well suited to accepting up to a 30%loading of medium thermal carbon black. Between 2 and 3percent of very small particle size furnace carbon black isincorporated into the polyethylene if sunlight resistance isrequired without significantly reducing the electrical properties.


33

XLPE insulated cables may be operated continuously at aconductor temperature of 90°C and intermittently at 130°Cduring emergency conditions. XLPE has good low temperatureproperties, shows increased resistance to corona when comparedwith thermoplastic polyethylene, and has good impact, abrasion,and environmental stress crack resistance.

Recent technology has resulted in XLPE insulation compoundsthat are resistant to degradation from treeing. Two processes areavailable for imparting tree resistance to the compound. Oneinvolves additives and the other involves copolymer technology.Additives tend to reduce the electrical properties of thepolyethylene insulation and one finds slightly lower values fordielectric strength and slightly higher dissipation factor whencomparing the tree retardant insulations to the standard material.

For general purpose low voltage cables, it is possible toincorporate up to 30% calcium carbonate into XLPE to reducethe cost. However, to maintain the best electrical properties,especially when immersed in water, the filled compound shouldnot be used.

In the Philippines, compounds incorporating approximately 30%thermal carbon black are used. These have the advantage ofimproved resistance to hot deformation and cut-throughresistance.

6.3 Insulation Resistance

In order that a reasonable factor of safety may be provided, thefollowing insulation resistance is suggested as a guide, where theinsulation is subjected to test:

a) For circuits of 2.0 mm2 or 3.5 mm2 conductors – 500,000ohms;

b) For circuits of 5.5 mm2 or larger conductors, a resistancebased upon the allowable ampacity of conductors asfollows:


34

-70

-65

-40

-40

-40

-60

-40

-40

-60

-55

-20

260

200

105

105

105

150

130

105

80

105

80

-100 0 100 200 300

Teflon

Silicone Rubber

CPE

EVA

Hypalon (CSPE)

EPR

XLPE

Polypropylene

Polythylene

PVC (Premium)

PVC (Standard)

25 to 50 amperes, inclusive 250,000 ohms51 to 100 amperes, inclusive 100,000 ohms101 to 200 amperes, inclusive 50,000 ohms201 to 400 amperes, inclusive 25,000 ohms401 to 800 amperes, inclusive 12,000 ohmsOver 800 amperes 5,000 ohms

The above listed values shall apply to installations withvoltage of 600 V or less. For voltages above 600 V, theminimum insulation resistance shall be 1,000,000 ohms perthousand volts or a fraction thereof. The foregoing is to bedetermined with all fixtures, switches, receptacles, andwiring devices in place and connected.

c) Where climatic conditions are such that the wiring orequipment is exposed to excessive humidity, it may benecessary to modify the foregoing provisions.

6.4 Thermal Characteristics

Selection of the right insulation materials depends on the expectedoperating temperature which the wire or cable will be subjected. Thenominal operating temperature in °C of some the insulation materialsare shown in Figure 2, below.

Figure 2: Nominal Temperature Range of Wire Insulations in °C


35

7. CABLE DESIGN AND CONSTRUCTION

An insulated cable appears to be a relatively simple electrical device but,in fact, it can be considered an electrical system with many components.To understand it, let us examine its components and basics of operation.For simplicity, the following discussion shall be confined to a singleconductor cable. However, these fundamentals also apply to multiple-conductor cables.

The basic components of an insulated cable are the following:

a) Conductor – materials that transmits electrical energyb) Shielding – also referred to as screening, are used for medium to

high voltage cables. Basically, the use of this stress controllayers is to achieve a symmetrical dielectric fields within thecable structure. For some voltage levels, shielding may beapplied over the conductor. At higher voltage levels, it is appliedover the conductor and the insulation. This results in theconfining of all the voltage gradients to within the cablestructure if the shield over the insulation is essentially atground potential.

c) Primary Insulation or Dielectric – prevents leakage of currentfrom the conductor to the surroundings. It protects life andprevents damage resulting from electrical discharge. It alsophysically protects the conductor.

d) Jacket – also called sheaths, serve several purposes such as theyprovide mechanical, thermal, chemical, and environmentalprotection to the insulated conductors they enclosed, act aselectrical insulation when used over shields or armor, easeinstallation and routing concerns by enclosing multiple insulatedconductors. They may also protect the characteristics of theunderlying insulation. For example, a thin nylon jacket overPVC enhances the abrasion and fluid resistance of a 600V cable.Sheathing may also include various forms of metallic armoring,tapes, or wires to enhance the physical properties of the cableand to provide a built-in protective electrically grounded conduitfor the insulated conductors. Commonly used jacketing materialsinclude extrusions of PE, PVC and Nylon. PVC, Nylon and PE


36

are applied using thermoplastic extrusion lines which heat thematerial to the melting point and form it over the core. Thematerial is then cooled, usually in a water trough, and woundonto a reel. Some heat is used to soften the material so that it canbe formed around the core. It is then necessary to crosslink thematerial to obtain its full properties.

Depending on the customer requirement and/or the application, a cablemay be composed of a couple of the above-stated components or all of it.For special cases, additional sheathing or armoring may be required.

An illustration of the construction and components of a medium voltagepower cable is shown below.

Figure 3: Construction of a Medium Voltage Power Cable

8. LOW VOLTAGE WIRES AND CABLES

Classification of voltage level seems to be arbitrary in most cases sincemany standard governing bodies in the world do not agree as to thedivisions in the voltage level. IEC define low voltage as those 1000 voltsand below while ICEA define low voltage to be 2000 volts and below.NEC and IEEE define low voltage as 600 volts and below.

Primarily all low voltage wires and cables are insulated except thoseused as neutral or grounding wire. With reference to their cableconstruction, they are non-shielded cable.


37

There are two basic components in a non-shielded cable. They are theconductor and the electrical insulation, sometimes referred to as thedielectric. A third component used in some cable designs is an outerjacket. The figure below shows the construction of a low-voltage non-shielded cable.

Figure 4: Low-Voltage Non-Shielded Cable Construction

Conductor

The conductor material can be copper or aluminum with either a solid orstranded.

The primary reason for the use of stranded conductors is improvedflexibility. The stranded conductors can be compressed or compacted toachieve desired flexibility, diameter, and load current density. For theconductor size, there are diameter differences between solid and thevarious types of stranded conductors. This is an important considerationin the selection of connectors and in the methods of splicing andterminating.

Electrical Insulation or Dielectric

The electrical insulation must provide adequate physical and electricalprotection between the energized conductor and the nearest electricalground to prevent electrical breakdowns. For low voltage cables, 600volts and below, the insulation thickness required to provide the necessaryphysical protection against damage is more than adequate to provide thenecessary dielectric strength.


38

Electrostatic Flux Lines Equipotential Lines

Another consideration in the design and application of cables is thedielectric field. In all electrical cables, irrespective of their voltageratings, there is a dielectric field present when the conductor is energized.This dielectric field is typically represented by electrostatic flux lines andequipotential lines between the conductor and electrical ground.

When a conductor is energized there are electrostatic lines of flux createdwithin the dielectric. The density of these flux lines is dependent upon themagnitude of the potential difference between the conductor and electricalground.The distance between the equipotential lines represents a voltagedifferential in the insulation. For a given voltage differential, these linesare closer together nearer the conductor.

Figure 5: Electrical Field of a Non-Shielded Cable

Above figure represents the electrical field of a non-shielded cable’scontact with a ground plane. It does not take into account the difference inthe dielectric constants of the insulation and the surrounding air.

Observe that the electrostatic flux lines are crowded in the insulationclosest to the ground. Also, the equipotential lines are eccentric in theirrelationship to the conductor and the cable dielectric surface. Thisdistortion of the fields is acceptable if the dielectric strength of thecable insulation is adequate to resist the concentration of the dielectricstresses. Low voltage non-shielded cables are usually designed to meetthis requirement.

Jacket/Sheaths

For special applications, a jacket is applied over the insulation. There areseveral materials available for use as jackets to provide the necessarychemical, physical, or thermal protection required by the application.


39

Low voltage wires and cables are primarily divided into two majorgroups, the building wires and secondary and service drop wires.

8.1 Building Wires

Building wires comprises the largest group of low voltage wires andcables which is primarily used in all residential, commercial andindustrial buildings. In the Philippines, the most common types ofthese building wires are the following:

8.1.1 Building Wires Types and Application

TW (Thermoplastic Moisture-Resistant)

The TW conductors are solid or stranded annealed (soft) copper,insulated with a moisture resistant and flame retardant polyvinylcompound (PVC). TW wire is used in interior wiring at circuitvoltages up to 600 volts. Maximum operating temperature is60°C in dry or wet application. Type TW building wire is used inresidential, commercial and industrial buildings for general-purpose lighting, appliance, power, control and relay panelapplications. It is used for low ampacity rated circuits. This typeof wire may be installed in conduits, ducts or raceways. Type TWwire is also suitable for installations in ambient temperaturesdown to -10°C.

THW (Thermoplastic Heat and Moisture Resistant)

The THW conductors are solid or stranded annealed (soft)copper, insulated with a tough heat and moisture resistant, andflame retardant polyvinyl compound (PVC). It is used in interiorwiring at circuit voltages up to 600 volts. Maximum operatingtemperature is 75°C in dry or wet application. It can be used forgeneral-purpose lighting, appliance, power, control and relaypanel applications. It is also applicable as machine tool wire andappliance wiring material. It is used for medium ampacity ratedcircuits. This type of wire may be installed in conduits, ducts orraceways.


40

THHN/THWN (Thermoplastic Heat and Moisture Resistant Wirewith Nylon Jacket)

The THHN/THWN conductors are solid or stranded annealed(soft) copper, insulated with a tough heat and moisture resistant,and flame retardant polyvinyl compound (PVC) with oil,chemical, and abrasion resistant nylon (polyamide) jacket. It isused in interior wiring at circuit voltages up to 600 volts.Maximum operating temperature is 90°C for dry applications(THHN) and 75°C for wet applications (THWN). It can be usedfor general-purpose lighting, power, control and relay panelapplications. It is also applicable for machine tool wire andappliance wiring material. It is used for high ampacity ratedcircuits. This type of wire may be installed in conduits, ducts orraceways.

The other types of conductor applications and insulations areshown in Annex B.

8.1.2 Building Wires Sizes and AmpacitySize and ampacity of building wires are given in Tables 10 and11, with reference to the Philippines Electrical Code based on anambient temperature of 30°C. Use appropriate correction factorspecified in the Philippine Electrical Code for ambienttemperature other than 30°C.


41

Table 10: Allowable Ampacities of Single-Insulated Conductors Rated0 Through 2 000 Volts in Free Air, Based on Ambient AirTemperature of 30°C

ConductorSizemm2

(mm dia.)

Temperature Rating of Conductor60°C 75°C 90°C 60°C 75°C 90°C

TypesTW,UF

TypesRHW,

THHW,THW,

THWN,XHHW,

ZW

TypesTBS, SA,SIS, FEP,

FEPB,MI,

RHH,RHW-2,THHN,THHW,THW-2,

TypesTW,UF

TypesRHW,

THHW,THW,

THWN,XHHW

TypesTBS, SA,

SIS, RHH,RHW-2,THHN,THHW,THW-2,

THWN-2,USE-2,XHH,

COPPER ALUMINUM

2 (1.6)3.5 (2)

5.5 (2.6)8 (3.2)

25304055

30355065

35405575

-253545

-304050

-354055

14223038

80105130155

95130160185

105140170195

658595115

80105115135

85115130155

506080

100

180205250290

220250300355

235260320370

135155185220

165185225265

185210255295

125150175200250

335375410440505

400440495540620

420475560570655

260295325345405

310355390410485

350400440465545

325375400500

600645675770

720775810930

770875875995

475510530620

560615640745

640690725835


42

Table 11: Allowable Ampacities of Insulated Conductors Rated 0Through 2 000 Volts, 60°C Through 90°C. Not More ThanThree Current-Carrying Conductors in Raceway, Cable, orEarth (Directly Buried), Based on Ambient Temperature of30°C

ConductorSize mm2

(mm dia.)

Temperature Rating of Conductor

60°C 75°C 90°C 60°C 75°C 90°C

TypesTW, UF

Types RHW,THHW,THW,

THWN,XHHW, ZW

Types TBS,SA, SIS, FEP,

FEPB, MI,RHH, RHW-

2, THHN,THHW,THW-2,

THWN-2,USE-2, XHH,

XHHW,XHHW-2,

ZW-2Types

TW, UF

Types RHW,THHW,THW,

THWN,XHHW

Types TBS,SA, SIS,

RHH, RHW-2, THHN,THHW,THW-2,

THWN-2,USE-2, XHH,

XHHW,XHHW-2,

ZW-2

COPPER ALUMINUM

2 (1.6)3.5 (2)

5.5 (2.6)8 (3.2)

20253040

20253550

25304055

-202530

-203040

-253545

14223038

557090

100

6585

110125

7090115130

40556575

50658090

658090

105

506080100

120135160180

145160195220

150170205225

95100120140

110120145170

125135165190

125150175200250

210240260280315

255280305330375

265295345355400

165185205220255

200225245265305

225250275.300345

325375400500

370395405445

435470485540

470530515580

305315335370

365380405440

410430460495

Apply appropriate adjustment factors if more than three (3) current carrying conductors ina raceway or cable with reference to the Philippine Electrical Code.


43

8.1.3 Resistances and Reactances

Resistances and reactances of copper wires in magnetic and non-magnetic conduits are given by Table 12, below:

Table 12: Copper Conductor Resistance and Reactance Data Line-to-neutral, mΩ/100 meter

ConductorSize mm2

(mm dia.)

Three-Single Conductor CablesIn Magnetic Duct Not In Magnetic Duct

Resistance"R"

Reactance"X"

Resistance"R"

Reactance"X"

Solid2 (1.6) 846.24 24.63 846.24 19.483.5 (2) 528.08 22.83 528.08 18.075.5 (2.6) 331.28 22.11 331.28 17.528 (3.2) 216.15 19.88 216.15 15.91

Stranded8 222.71 19.45 222.71 15.5514 140.06 18.60 140.06 14.8922 88.23 17.38 88.23 13.9130 55.76 16.33 55.43 13.0538 44.28 16.53 43.95 13.2250 35.42 16.24 35.10 12.9960 28.21 15.84 27.88 12.6680 22.63 15.32 21.98 12.23100 17.81 14.86 17.48 11.87125 15.48 15.25 15.06 12.20150 12.96 14.83 12.46 11.84200 10.00 14.46 9.54 11.58250 8.20 14.17 7.71 11.35325 7.08 14.14 6.53 11.28400 5.94 13.94 5.35 11.15500 5.02 13.74 4.43 10.99

Note: Typical values, use exact values if available.


44

8.2 Secondary and Service Cables

These cables are used by Distribution Utilities in low voltage powerdistribution. Both cables have the same construction; the difference isin the application. Secondary cables are those that are connected tothe distribution transformer and traverses from pole to pole whileservice drop cables are those that connect the customer’s serviceentrance wires to the secondary cable or distribution transformer.

8.2.1 Overhead secondary and service cables

In the Philippines, majority of the distribution system areoverhead construction. Most overhead secondary and servicecables are multiplex cables with sizes that are typically based inAWG. Cables are insulated by either polyethylene (PE) orcrosslinked polyethylene (XLPE) material. Basically, these cablesare classified based on the number of conductors twisted together(e.g. duplex, triplex, and quadruplex cables).

8.2.2 Underground secondary and service cables

Underground secondary and service cables are conductorsinstalled in conduit or directly buried in the earth and enter thebuilding metering facilities, switch, or service equipment. TypeUSE service cables are similar in construction to the generalpower cables for direct burial in earth.

Tables 13 & 14 show the characteristics of the different types ofMultiplex Secondary and Services Copper and Aluminum Cables,respectively. While, Tables 15 & 16 show the characteristics ofthe types of Single Conductors for Underground Service forCopper and Aluminum, respectively.


45

Table 13. Copper Multiplex Secondary and Services Cables

Code Word

Phase Conductor NeutralCable

Weightper 1000ft (lbs)

Ampacity

Sizes(# of

wires)

InsulationThickness

(mils)

Sizes(# of

wires)

RatedStrength

(lbs.)PE XLPE

DUPLEX

Theta 8 (7) 45 10 (1) 529 95 70 85

Kappa 8 (7) 45 8 (7) 777 114 70 85

Sigma 6 (7) 45 6 (7) 1228 177 90 110

TRIPLEX

Pica 8 (7) 45 10 (1) 529 158 70 85

Garamond 8 (7) 45 8 (7) 777 177 70 85

Gothic 6 (7) 45 6 (7) 1228 273 90 110

Casion 4 (7) 45 4 (7) 1938 425 115 145

Primer 2 (7) 45 4 (7) 1938 588 155 195

Century 2 (7) 45 2 (7) 3050 664 155 195

Corinthian 1/0 (19) 60 1/0 (7) 4752 1055 205 265

Doric 2/0 (19) 60 2/0 (7) 5926 1319 235 300

QUADRUPLEX

Tallahassee 6 (7) 45 6 (7) 1228 369 75 95

Richmond 4 (7) 45 4 (7) 1938 573 100 125

Seattle 2 (7) 45 2 (7) 3050 893 135 170

Nashville 1/0 (19) 60 1/0 (7) 4752 1420 180 230

Lincoln 2/0 (19) 60 2/0 (7) 5926 1773 205 265

Raleigh 3/0 (19) 60 3/0 (7) 7366 2220 235 305

Denver 4/0 (19) 60 4/0 (7) 9154 2781 270 350

Ampacity figures for black insulation only. Based on conductor temperature of 75°C forpolyethylene insulated conductors, 90°C for XLPE insulated conductors, ambienttemperature of 40°C; 2 ft./sec. wind in sun. Source: Southwire


46

Table 14: Aluminum Multiplex Cables with ACSR Neutral Messenger

Code Word

Phase Conductor Neutral CableWeight

per1000 ft

(lbs)

Ampacity

Sizes(# of

wires)

InsulationThickness

(mils)

Sizes(Stranding)

RatedStrength

(lbs.)PE XLPE

DUPLEX

Shepherd 6 (7) 45 6 (6/1) 1190 75 70 85

Terrier 4 (7) 45 4 (6/1) 1860 115 90 115

Chow 2 (7) 45 2 (6/1) 2850 176 120 150

Bull 1/0 (9) 60 1/0 (6/1) 4380 280 160 205

TRIPLEX

Voluta 6 (7) 45 6 (6/1) 1190 114 70 85

Periwinkle 4 (7) 45 4 (6/1) 1860 172 90 115

Conch 2 (7) 45 2 (6/1) 2850 262 120 150

Neritina 1/0 (7) 60 1/0 (6/1) 4380 420 160 205

Cenia 1/0 (9) 60 1/0 (6/1) 4380 414 160 205

Runcina 2/0 (7) 60 2/0 (6/1) 5310 520 185 235

Triton 2/0 (11) 60 2/0 (6/1) 5310 512 185 235

Mursia 3/0 (17) 60 3/0 (6/1) 6620 635 215 275

Zuzara 4/0 (18) 60 4/0 (6/1) 8350 789 245 315

Limpet 336.4 (19) 60336.4(18/1)

8680 1167 325 420

QUADRUPLEX

Hackney 4 (7) 45 4 (6/1) 1860 229 80 100

Palomino 2 (7) 45 2 (6/1) 2850 347 105 135

Costena 1/0 (9) 60 1/0 (6/1) 4380 549 140 180

Grullo 2/0 (11) 60 2/0 (6/1) 5310 677 160 205

Suffolk 3/0 (17) 60 3/0 (6/1) 6620 837 185 235

Appaloosa 4/0 (18) 60 4/0 (6/1) 8350 1038 210 275

Bronco 336.4 (19) 60336.4(18/1)

8680 1568 280 370

Conductor temperature of 90°C for XLPE, 75°C for PE; ambient temperature of 40°C;emissivity 0.9; 2 ft./sec. wind in sun. Source: Southwire


47

Table 15: Single Copper Conductors for Underground Service

Size(AWG

orkcmil)

Numberof

Strands

CompositeInsulation-Thickness

(mils)

CompositeInsulation-Thickness

(mm)

Approx.O.D.

(Inches)

Approx.O.D.(mm)

Approx.Net

Weightper

1000 ft.(lbs)

Ampacity

90°C 75°C

14 1 45 1.14 0.16 4.06 23 15 15

14 7 45 1.14 0.17 4.57 25 15 15

12 1 45 1.14 0.18 4.57 32 20 20

12 7 45 1.14 0.19 4.83 34 20 20

10 1 45 1.14 0.2 5.08 46 30 30

10 7 45 1.14 0.21 5.33 48 30 30

8 7 60 1.52 0.27 6.86 77 55 50

6 7 75 1.91 0.34 8.64 123 75 65

4 7 75 1.91 0.38 9.75 176 95 85

2 7 75 1.91 0.43 11 257 130 115

1 19 100 2.54 0.52 13.16 349 150 130

1/0 19 100 2.54 0.56 14.1 413 170 150

2/0 19 100 2.54 0.6 15.14 509 195 175

3/0 19 100 2.54 0.64 16.33 622 225 200

4/0 19 100 2.54 0.7 17.68 766 260 230

250 37 130 3.3 0.81 20.57 944 290 255

350 37 130 3.3 0.91 23.04 1273 350 310

500 37 130 3.3 1.03 26.19 1764 430 380

750 61 145 3.68 1.28 32.51 2625 535 475

1000 61 145 3.68 1.44 36.58 3443 615 545

Source: Okonite


48

Table 16: Single Aluminum Conductor for Underground Service

Code WordSize

(# of Wires)

ConductorDiameter

(inch)

InsulationThickness

(inch)

InsulationDiameter

(inch)

TotalWeight

(lb/1000 ft)

Impedance (ohm/1000ft) *

AC Resistance InductiveReactance

@60Hz@ 75°C @ 90°C

CORNELL/XLP 8 (7) 0.141 0.06 0.26 34 1.28 1.35 0.047

PRINCETON/XLP 6 (7) 0.178 0.06 0.3 47 0.807 0.847 0.0447

MERCER/XLP 4 (7) 0.225 0.06 0.35 67 0.508 0.533 0.0426

CLEMSON/XLP 2 (7) 0.283 0.06 0.41 97 0.319 0.335 0.0409

KENYON/XLP 1 (19) 0.322 0.08 0.49 128 0.253 0.266 0.0411

HARVARD/XLP 1/0 (19) 0.362 0.08 0.52 154 0.201 0.211 0.0402

YALE/XLP 2/0 (19) 0.406 0.08 0.57 186 0.159 0.167 0.0394

TUFTS/XLP 3/0 (19) 0.456 0.08 0.62 225 0.126 0.133 0.0387

BELOIT/XLP 4/0 (19) 0.512 0.08 0.68 274 0.1 0.105 0.038

HOFSTRA/XLP 250 (37) 0.558 0.095 0.75 329 0.085 0.0892 0.0382

GONZAGA/XLP 300 (37) 0.611 0.095 0.81 385 0.071 0.0744 0.0377

RUTGERS/XLP 350 (37) 0.66 0.095 0.85 439 0.0609 0.0639 0.0373

DARTMOUTH/XLP 400 (37) 0.706 0.095 0.9 493 0.0534 0.056 0.0369

BROWN/XLP 450 (37) 0.749 0.095 0.94 547 0.0476 0.0499 0.0366

EMORY/XLP 500 (37) 0.789 0.095 0.98 601 0.0429 0.045 0.0364

DUKE/XLP 600 (61) 0.866 0.11 1.09 725 0.036 0.0377 0.0365

FURMAN/XLP 700 (61) 0.935 0.11 1.16 830 0.0311 0.0325 0.0362

SEWANEE/XLP 750 (61) 0.968 0.11 1.19 883 0.0291 0.0305 0.036

FORDHAM/XLP 1000 (61) 1.118 0.11 1.34 1144 0.0223 0.0233 0.0354

* At random (calculated as 1.5 x cable OD) spacing between conductors. Source: Nexans


49

9. MEDIUM AND HIGH VOLTAGE WIRES AND CABLES

There is no consensus among standard governing bodies like (i.e., IEC,ANSI, IEEE, UL, NEC and others) concerning the classification ofvoltage level. Thus, for clarity of this manual we will utilize IEEE voltagelevel classifications wherein 601 V to 69,000 V is medium voltage and69,001 V to 230,000 V is high voltage. Furthermore, conductors are alsoclassified according to their degree of insulation covering (i.e. bare,covered, and insulated). Basically, construction of the wires and cables isthe same or similar for medium and high voltage applications.

9.1 Bare Conductors

Bare conductors are those without covering and primarily used foroverhead power transmission and distribution application. Insulatingmedium is air wherein the conductors are spaced from each other andany grounded object based on the system voltage. Insulators (e.gporcelain, glass, and polymers) are used to support the conductors andinsulate these from the supporting structure such as tower or pole.

Copper and aluminum conductors are commonly used for thisapplication. However, there are instances where economics dictate theuse of conductors with low conductivity such as galvanized steel,copper-clad steel (Copperweld) or aluminum-clad steel (Alumoweld)in the distribution system. In such cases, the conductor losses arelower than the cost of recovering the investment in the distributionline if copper or aluminum conductor is used. In this field ofapplication, the most dominant conductor used by the industry is thealuminum conductor steel reinforced (ACSR).

The succeeding tables (i.e., 17 to 19) show the physical and electricaldata for copper and aluminum conductors.


50

Table 17: Bare Stranded Copper Wires Physical and Electrical Data

Size(AWG or

kcmil)

Stran-ding

StrandingClass

WeightPer 1000ft. (Ibs.)

Dia.(mils)

Hard-DrawnMedium-Hard

DrawnSoft-Drawn(Annealed)

AllowableAmpacityRated

Strength(lbs)

DC ResistanceOhms/1000 ft

@ 20°C

RatedStrength

(lbs)


@ 20°C

RatedStrength

(lbs)


@ 20°C

8 7 B 51 146 777 0.6663 610 0.6629 499 0.6408 95

6 7 B 81 184 1228 0.4191 959 0.4169 794 0.403 130

4 7 A, B 128.9 232 1938 0.2636 1505 0.2622 1320 0.2534 170

3 7 A, B 162.5 260 2433 0.209 1885 0.2079 1670 0.201 200

2 7 A, B 204.9 292 3050 0.166 2360 0.165 2110 0.1578 230

1 7 A 258.4 328 3801 0.1316 2955 0.1309 2552 0.1252 265

1/0 7 A, AA 326.1 368 4752 0.1042 3705 0.1037 3221 0.1002 310

1/0 19 B 326.1 373 4752 0.1042 3705 0.1037 3221 0.1002 310

2/0 7 A, AA 410.9 414 5926 0.08267 4640 0.08224 4062 0.07949 355

2/0 19 B 410.9 418 6690 0.08267 4765 0.08224 4024 0.07949 355

3/0 7 A, AA 518.1 464 7366 0.06556 5812 0.06522 5118 0.06304 410

4/0 7 A, AA 653.3 522 9154 0.05199 7278 0.05172 6459 0.04999 480

4/0 19 B 653.3 528 9617 0.05199 7479 0.05172 6453 0.04999 480

250 19 A 771.9 574 11360 0.044 8836 0.04378 7627 0.04231 530

250 37 B 771.9 575 11600 0.044 8952 0.04378 7940 0.04231 530

300 19 A 926.2 628 13510 0.03667 10530 0.03648 9160 0.03526 590

350 19 A 1080.6 679 15590 0.03143 12200 0.03127 10680 0.03022 650

500 37 A, B 1543.8 814 22510 0.022 17550 0.02189 15240 0.02116 810

600 37 A, AA 1852.5 891 27020 0.01834 21060 0.01825 18300 0.01763 910

750 61 A, B 2315.6 998 34090 0.01467 26510 0.01459 22890 0.0141 1040

1000 61 A, B 3087.5 1152 45030 0.011 35100 0.01094 30500 0.01058 1240

Ampacity based on 75°C conductor temperature; 25°C ambient temperature; 2 ft/sec wind in sun.Source: Southwire


51

Table 18: Aluminum Conductor Steel Reinforced (ACSR) Physical Data

Codeword

Size(AWG or

kcmil)

No. ofWires

Diameter (inch) Weight (lb/1000ft) RatedStrength

(lbs)Steel Wire Al WireSteelCore

CompleteConductor

Al Steel Total

Turkey 6 6/1 0.0661 0.0661 0.066 0.198 24.4 11.6 36 1190

Swan 4 6/1 0.0834 0.0834 0.083 0.25 39 18.4 57.4 1860

Swanate 4 7/1 0.1029 0.0772 0.103 0.257 39 28 67 2360

Sparrow 2 6/1 0.1052 0.1052 0.105 0.316 61.9 29.3 91.2 2850

Sparate 2 7/1 0.1299 0.0974 0.13 0.325 62.3 44.7 102 3640

Robin 1 6/1 0.1181 0.1181 0.118 0.355 78.1 36.9 115 3550

Raven 1/0 6/1 0.1327 0.1327 0.133 0.398 98.4 46.6 145 4380

Quail 2/0 6/1 0.1489 0.1489 0.149 0.447 124.2 58.8 183 5310

Pigeon 3/0 6/1 0.1672 0.1672 0.167 0.502 155.9 74.1 230 6620

Penguin 4/0 6/1 0.1878 0.1878 0.188 0.563 197.6 93.4 291 8350

Waxwing 266.8 18/1 0.1217 0.1217 0.122 0.609 249.8 39.2 289 6880

Partridge 266.8 26/7 0.0788 0.1013 0.236 0.642 250.4 115.6 366 11300

Merlin 336.4 18/1 0.1367 0.1367 0.137 0.684 315.5 49.5 365 8680

Linnet 336.4 26/7 0.0884 0.1137 0.265 0.72 316.5 145.5 462 14100

Oriole 336.4 30/7 0.1059 0.1059 0.318 0.741 317 209 526 17300

Chickadee 397.5 18/1 0.1486 0.1486 0.149 0.743 372.5 58.5 431 9940

Ibis 397.5 26/7 0.0961 0.1236 0.288 0.783 374.1 171.9 546 16300

Pelican 477 18/1 0.1628 0.1628 0.163 0.814 446.8 70.2 517 11800

Flicker 477 24/7 0.094 0.141 0.282 0.846 449.5 164.5 614 17200

Hawk 477 26/7 0.1053 0.1354 0.316 0.858 448.6 206.4 655 19500

Hen 477 30/7 0.1261 0.1261 0.378 0.883 449.7 296.3 746 23800

Osprey 556.5 18/1 0.1758 0.1758 0.176 0.879 521.1 81.9 603 13700

Parakeet 556.5 24/7 0.1015 0.1523 0.305 0.914 524.2 191.8 716 19800

Dove 556.5 26/7 0.1138 0.1463 0.341 0.927 523.9 241.1 765 22600

Rook 636 24/7 0.1085 0.1628 0.326 0.977 598.8 219.2 818 22000

Grosbeak 636 26/7 0.1216 0.1564 0.365 0.99 598.7 275.3 873 25200

Drake 795 26/7 0.136 0.1749 0.408 1.108 749 344 1093 31500

Tern 795 45/7 0.0886 0.1329 0.266 1.063 748.9 146.1 895 22100

Rail 954 45/7 0.0971 0.1456 0.291 1.165 899 176 1075 25900

Cardinal 954 54/7 0.1329 0.1329 0.399 1.96 899 329 1228 33800

Curlew 1033.5 54/7 0.1383 0.1383 0.415 1.245 973 356 1329 36600

Bluejay 1113 45/7 0.1049 0.1573 0.315 1.259 1049 205 1254 29800

Bittern 1272 45/7 0.1121 0.168 0.336 1.345 1198 234 1432 34100

Lapwing 1590 45/7 0.1253 0.188 0.376 1.504 1498 292 1790 42200

Bluebird 2156 84/19 0.0961 0.1602 0.481 1.762 2040 468 2508 60300

Source: Nexans


52

Table 19: Aluminum Conductor Steel Reinforced (ACSR) Electrical Data

Code word

Size(AWG

orkcmil)

Resistance (ohm/kft) Reactance at 60 Hz**

Ampacity*(A)DC at

20°CAC at25°C

AC at50°C

AC at75°C

Capacitive(megohm-kft)

Inductiveat 25°C

(ohm/kft)

Inductiveat 50°C

(ohm/kft)

Inductiveat 75°C

(ohm/kft)

Turkey 6 0.642 0.655 0.75 0.816 0.751 0.12 0.139 0.144 105

Swan 4 0.403 0.412 0.479 0.522 0.715 0.115 0.131 0.137 140

Swanate 4 0.399 0.407 0.463 0.516 0.71 0.113 0.124 0.13 140

Sparrow 2 0.253 0.259 0.308 0.336 0.678 0.11 0.123 0.128 185

Sparate 2 0.251 0.256 0.297 0.33 0.674 0.109 0.118 0.121 185

Robin 1 0.201 0.206 0.247 0.27 0.66 0.107 0.119 0.122 210

Raven 1/0 0.159 0.163 0.197 0.216 0.642 0.104 0.114 0.116 240

Quail 2/0 0.126 0.13 0.162 0.176 0.624 0.102 0.112 0.113 275

Pigeon 3/0 0.1 0.103 0.121 0.145 0.606 0.0992 0.108 0.109 315

Penguin 4/0 0.0795 0.0822 0.107 0.116 0.597 0.0964 0.105 0.105 365

Waxwing 266.8 0.0644 0.0657 0.0723 0.0788 0.576 0.0903 0.0903 0.0903 445

Partridge 266.8 0.0637 0.0652 0.0714 0.0778 0.565 0.0881 0.0881 0.0881 455

Merlin 336.4 0.051 0.0523 0.0574 0.0625 0.56 0.0826 0.0826 0.0826 515

Linnet 336.4 0.0506 0.0517 0.0568 0.0619 0.549 0.0854 0.0854 0.0854 530

Oriole 336.4 0.0502 0.0513 0.0563 0.0614 0.544 0.0843 0.0843 0.0843 530

Chickadee 397.5 0.0432 0.0443 0.0487 0.0528 0.544 0.0856 0.0856 0.0856 575

Ibis 397.5 0.0428 0.0438 0.0481 0.0525 0.539 0.0835 0.0835 0.0835 590

Pelican 477 0.036 0.0369 0.0405 0.0441 0.528 0.0835 0.0835 0.0835 640

Flicker 477 0.0358 0.0367 0.0403 0.0439 0.524 0.0818 0.0818 0.0818 670

Hawk 477 0.0357 0.0366 0.0402 0.0438 0.522 0.0814 0.0814 0.0814 660

Hen 477 0.0354 0.0362 0.0398 0.0434 0.517 0.0803 0.0803 0.0803 660

Osprey 556.5 0.0309 0.0318 0.0348 0.0379 0.518 0.0818 0.0818 0.0818 710

Parakeet 556.5 0.0307 0.0314 0.0347 0.0377 0.512 0.0801 0.0801 0.0801 720

Dove 556.5 0.0305 0.0314 0.0345 0.0375 0.51 0.0795 0.0795 0.0795 730

Rook 636 0.0268 0.0277 0.0303 0.033 0.502 0.0786 0.0786 0.0786 780

Grosbeak 636 0.0267 0.0275 0.0301 0.0328 0.499 0.078 0.078 0.078 790

Drake 795 0.0214 0.0222 0.0242 0.0263 0.482 0.0756 0.0756 0.0756 910

Tern 795 0.0216 0.0225 0.0246 0.0267 0.488 0.0769 0.0769 0.0769 890

Rail 954 0.018 0.0188 0.0206 0.0223 0.474 0.0748 0.0748 0.0748 970

Cardinal 954 0.0179 0.0186 0.0205 0.0222 0.47 0.0737 0.0737 0.0737 990

Curlew 1033.5 0.0165 0.0172 0.0189 0.0205 0.464 0.0729 0.0729 0.0729 1040

Bluejay 1113 0.0155 0.0163 0.0178 0.0193 0.461 0.0731 0.0731 0.0731 1070

Bittern 1272 0.0135 0.0144 0.0157 0.017 0.451 0.0716 0.0716 0.0716 1160

Lapwing 1590 0.0108 0.0117 0.0128 0.0138 0.434 0.0689 0.0689 0.0689 1340

Bluebird 2156 0.00801 0.00903 0.00977 0.0105 0.409 0.0652 0.0652 0.0652 1610

* Ampacity is with sun and wind at 2 ft/s ** Reactance at 1 foot equivalent spacing

Source: Nexans


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9.2 Covered Conductors

Covered conductors are bare conductors with thin insulation coveringused for overhead power distribution system. These are used forpower distribution circuits that transverse along routes with heavytree growth. The covering does not fully insulate the conductor but itis thick enough to reduce the chances of flashover whenever a treebranch falls between the conductors. Covered conductor is alsocommonly known as tree wire. Also, it helps minimize faults causedby animals and enable distribution utilities to utilize conductorconfigurations with tight spacing. Covered conductors are commonlyused as a cost-effective method for increasing overhead linereliability.

The conductor materials are typically copper or aluminum or otherconductors designed to give a balance between strength andconductivity such as ACSR. Tree wire is commonly covered byinsulating materials such as polyethylene, XLPE, or EPR. Insulationthickness typically ranges from 30 to 150 mils. Tree wires mustalways be treated as bare conductors. However, closer spacings areallowed for this type of conductor.

While covered conductors help against trees, it has several setbackscompared to bare conductors. The covering may be susceptible todegradation due to ultraviolet radiation, tracking, and mechanicaleffects that cause cracking. Also, covered conductors are susceptibleto burn-downs. Burn-down is when a conductor burns through ormelts and falls to the ground. A covered conductor line can sufferburn-down due to lightning strikes, excessive tracking over time,vibration fatigue or tree branches falling on the line. The risk of burn-down can be reduced by suitable lightning protection systems,reduction of electrical stresses, improved tree trimming, reducedcarbon black content in the sheath material, and proper installationand tensioning.

The additional covering adds cost to the conductor such that acovered conductor line would cost about at least 20% more than abare conductor line. Covered conductors are heavier and have largerdiameters so wind loading is higher than bare conductors. Also, adamage cover makes it susceptible to corrosion, primarily from water.


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If water penetrates the covering, it settles at the low points and causescorrosion since the covering prevents the trapped water fromevaporating. Water enters the conductor at pinholes caused bylightning strikes, cover damage caused by abrasion, and at holespierced by connectors. In contrast, rain simply washes over bareconductors and evaporation takes care of moisture.

There will be a low charging current flowing along the coveredconductor sheath since its surface is insulating but not fully insulated.This arises because the sheath forms an insulating layer between thehigh voltage conductor (metal) and the pin or post insulator to earth.This current will normally be less than 0.3mA which flows phase-phase or phase-ground. This current is held low to reduce trackingand erosion, especially under polluted conditions. Metal helical tiesform an intermediate electrode and can cause discharge problems atthe ends if bare. Connecting helical ties with any insulating piercingconnectors (IPCs) or use of semi-conducting plastic ties eliminatesthis problem.

For a covered conductor line, insulation piercing connectors (IPC) areused. IPC contains teeth that penetrate through the insulation to havecontact with the conductor and complete a connection.

Tables 20 and 21 show the relevant data of Copper and ACSRCovered Conductors, respectively.

Spacer cables are also alternatives to Covered Cables and performwell in areas with dense trees. Spacer cables are of bundledconfiguration using a messenger wire with a polymetric supportcradle holding up the three phases. The spacer cables’ reactiveimpedance is smaller because it significantly reduces spacing thantypical overhead constructions.


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Table 20: Copper Single Layer Covered Conductors Data

Size(AWG

orkcmil)

Stran-ding

CoverThick.(mils)

O.D.Covered(mils)

CopperContent

Per1000 ft.

(lbs.)

Weight Per1000 ft. (lbs.) DC

ResistanceΩ/1000

ft.@20°C

AllowableAmpacity

+XLPE PE

6 7 30 238 81 90.3 90.3 0.503 130

4 7 30 285 128.9 140.8 140.8 0.316 175

2 7 45 373 204.9 227.1 227.1 0.199 230

1/0 7 60 477 326.1 363.3 363.3 0.125 305

2/0 7 60 522 410.9 453.3 453.3 0.0992 350

3/0 7 60 570 518.1 565.6 565.6 0.0788 405

4/0 7 60 626 653.3 707.6 707.6 0.0625 465

250 19 60 677 771.9 825.4 825.4 0.0530 520

300 19 60 729 926.2 984.6 984.6 0.0442 580

350 19 60 779 1080.6 1144.5 1144.5 0.0380 640

500 37 80 950 1543.8 1637.2 1637.2 0.0278 785

750 61 80 1128 2315.6 2422.8 2422.8 0.0182 995

1000 61 95 1307 3087.5 3234 3234 0.0140 1180

Source: Southwire


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Table 21: 2-Layer 15kV ACSR Tree Wire

Size(AWG

orkcmil)

StrandingConductorDiameter

(mils)

CoveringThickness

(mils)CableO.D.(mils)

RatedStrength

(lbs)

Weightper

1000ft. (lbs)Inner

LayerOuterLayer

1/0 6/1 398 75 75 698 4161 255

2/0 6/1 447 75 75 747 5045 303

3/0 6/1 502 75 75 802 6289 362

4/0 6/1 563 75 75 863 7933 432

266.8 18/1 609 75 75 909 6536 441

266.8 26/7 642 75 75 942 10735 452

336.4 18/1 684 75 75 984 8246 536

336.4 26/7 720 75 75 1020 13395 555

336.4 30/7 741 75 75 1041 16435 621

397.5 18/1 743 75 75 1043 9443 611

397.5 24/7 772 75 75 1072 13870 609

477 24/7 846 75 75 1146 16340 719

477 26/7 858 75 75 1158 18525 762

477 30/7 883 75 75 1183 22610 854

556.5 18/1 879 75 75 1179 13015 813

556.5 24/7 914 75 75 1214 18810 828

556.5 26/7 927 75 75 1227 21470 878

636 18/1 940 75 75 1240 14915 912

636 24/7 977 75 75 1277 20900 936

636 26/7 990 75 75 1290 23940 993

795 26/7 1108 80 80 1428 29925 1234

795 45/7 1063 80 80 1383 20995 1031

Source: Southwire


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9.3 Insulated Cables

Majority of insulated cables are utilized for undergroundtransmission and distribution systems. Being insulated for voltageshigher than 2 kV, that these cables are typically shielded.

9.3.1 Construction

The fundamental difference between non-shielded and shieldedcables is the inclusion of outer conducting components in thecable system. The basic components of a shielded cable areshown below.

Figure 6: Construction of Shielded Power Cable

Conductor

The conductors used in shielded cables are basically the same asthose used in non-shielded cables, with copper and aluminum asthe conductor.

Conductor Shield or Screen

The conductor shield is usually a semi-conducting materialapplied over the conductor circumference to shield out the surfaceirregularities of the conductor. With this shield, the resultingdielectric field lines will not be distorted by the shape of the outerstrands or other conductor contours. It prevents the formation ofdestructive discharges at the interface between the conductor andinsulation. Otherwise, the electrical stress around the conductorswould produce partial discharges on the surface of the insulationwhich deteriorates it and eventually results to cable failure. Also,it is essential that this stress control layer be compatible with theconductor and the cable insulation.


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This layer also provides a smooth and compatible surface forthe application of the insulation. The conductor shield isextruded simultaneously with the insulation for a void-free bondbetween conductor shield and insulation. The shield may alsobe used to facilitate splicing and termination of the cable.

Insulation

This is the part of the cable that is relied upon to insulate theconductor from other conductor or conductive object or fromground. The differences between the insulation for shielded cablesas compared to non-shielded cables include material, processtechnology, and testing. The insulation thickness is primarilyinfluenced by the operating voltage. Therefore, the higher thevoltage, the thicker the insulation.

Insulation Shield or Screen

This absorbs the symmetrical radial stresses and discharges on thesurfaces of the insulation. It protects the cables from inducedpotentials. Shields help attenuate, make uniform and reduce thesurge potential stresses on the insulation. It increases safety tohumans and removes the risk of fire due to electrical discharges onthe cable surface.

The insulation shield or screen is a two-part system composed ofan auxiliary and a primary shield.

An auxiliary shield is usually a semi-conducting, non-metallicmaterial over the insulation circumference. It must be smooth,compatible with the insulation, and exhibit an acceptably lowvoltage drop throughout its thickness. A commonly usedauxiliary shield consists of an extruded semi-conductingpolymer to permit easy removal during field termination, butyet to remain uniformly bonded to the insulation throughoutthe cable length.

A primary shield is a metallic shield over the circumferenceof the auxiliary shield. It may consist of copper tape orConcentric Neutral (CN) wires. These concentric neutralwires are usually annealed.


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CN wires serve two purposes, namely; they function as themetallic component of the insulation shield and as aconductor for the neutral return current. Their cross-sectional area must be properly sized in order to function asthe neutral conductor.

The primary shield must be capable of conducting thesummation of the “leakage” currents to the nearest groundwith an acceptable voltage drop. In some cases, it must also becapable of conducting fault currents.

The primary shield, by itself, without an intervening auxiliaryshield, cannot achieve acceptable physical contact with theinsulation surface. A relatively resilient auxiliary shield isnecessary to eliminate arcing between the insulation surfaceand the primary shield.

If the insulation shield is effectively at ground potential, noresulting distortion of the electrostatic flux or equipotential lineswill occur. The grounding of the insulation shield is the electricalconnection between the metallic component of the insulationshield and the system ground. This grounding of the insulationshield results in symmetrical dielectric fields. Electrostatic fluxlines are spaced symmetrically and perpendicular to equipotentiallines. The equipotential lines are concentric and parallel withrespect to each other, the conductor shield and the insulationshield. The presence of the shielding results in field lines asdepicted in Figure 7. In addition, grounding promotes personnelsafety by minimizing potentials on the outer surface of the cableand its accessories.

The shielding of the cable system can either be single-pointed or multiple-pointed grounding. A single-point groundedsystem is frequently referred to as an open circuit shield. Sincethe shield is grounded at a single point, there is no closed loopfor the flow of induced shield currents. A multiple-pointgrounded system, on the other hand, is one that has grounds atmore than one point. It is frequently called a closed or short-circuit shield system.


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Each of the arrangements has its particular advantages anddisadvantages for selection. Knowledge of the total systemshould be taken into account when making these decisions.

In a shielded cable, the voltage difference betweenconductor and electrical ground is contained within the cable.For a non-shielded cable, the voltage difference betweenconductor and electrical ground is divided between the cableinsulation and any intervening air or other materials.

Figure 7: Electrical Field of a Shielded Cable

Insulation

Conductor

Conductor Shield

Insulation Shield

Electrostatic Flux Lines

Equipotential Lines


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In Figure 7, observe that the field lines are closer to each othernear the conductor shield as compared to the insulation shield.The radial stresses or voltage gradients increase near theconductor.

Jackets/Sheaths

These cable components provide environmental protection overthe insulation shielding system. The material used can be anextruded jacket of synthetic material, metal sheaths/wires,armoring, or a combination of these types of materials.

9.3.2 Electrical Losses in Cables

When the cable is energized and carrying load, heat, which mustbe dissipated to the surrounding medium, is generated by theconductor, dielectric and sheath losses.

The heat generated by these losses in the conductor, thedielectric, the sheath and armor has to pass to the surroundingmedium, which may be the ground, air, water or some othermaterial. The current carrying capacity of an electric cable isnormally dictated by the maximum temperature of the conductor.The components of the cable, in addition to meeting theelectrical requirements, must also have as low a thermalresistivity, as possible, to ensure that the heat can be dissipatedefficiently. If the rate of rise of heat generation is greater than therate of rise of heat dissipation, the cable temperature willcontinue to increase which will result in the overheating of thecable and eventual breakdown.

9.3.3 Advantages of Shielded Cables

Electrical insulation surrounding a conductor creates a capacitorwhen the conductor is electrically energized. Thus, all insulatedconductors are capacitors.

In the majority of non-shielded cable systems, the cable surfacemakes intermittent contact with an electrical ground. Whereintimate contact with this ground is not made, the intervening air


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spaces also act primarily as capacitors in ac circuits and asresistors in dc circuits. This forms a series of cable dielectric andair dielectric. Voltage across this circuit varies along the lengthof the cable depending on the voltage across the air gap. Thecable surface becomes a floating voltage point in a voltagedivider. This floating point voltage can vary considerably,depending on the cable design and the characteristics of the airgap. If the voltage is high enough, the cable surface canexperience detrimental surface tracking of arcing discharges toelectrical ground. The cable surface can also become potentiallyhazardous causing an electrical shock if contacted by fieldpersonnel.

Shielding the cable insulation surface and grounding of thisshielding eliminates tracking and arcing discharges. Thegrounding of this shield prevents the accumulation of anelectrical potential on the surface of the cable that could behazardous to any individual that comes into contact with thecable surface.

10. INSTALLATION OF WIRES AND CABLES

10.1 Maximum Allowable Tensions on Conductors

Care should be taken during installation of cables to prevent damagethat can result to future service failures. In preparing for a conductorpull, it is just as important to cover the other details as it is to assurethat the conductor does not exceed maximum sidewall pressure,minimum bending radii or maximum pulling tensions. These andother considerations can make the difference between a goodinstallation and one with damaged conductors.

Mechanical stresses during installation are generally more severethan those encountered while in service. The following informationprovides guidance in recognizing these conditions and provides amethodology to aid in keeping them within acceptable limits.


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10.1.1 Maximum Allowable Tension

Calculations should be made whether the pull looks easy orimpossible, making the decision as where to pull an obviouschoice. When an obscure situation is encountered, the entire pullshould be reviewed. This review may include more rigorouscalculations or trial pulls. A final decision should be made basedon installation factors known to the end user and installer.

The sizes of the conduit are determined based on the calculationsof clearances, jamming, and fill. Pulling tensions may beevaluated by determining the maximum tension based on thepulling device used, and the maximum tension that can beapplied to the conductors. The lesser of these two values is themaximum allowable tension. After calculating the pullingtensions, sidewall pressures may be calculated.

Do not exceed the allowable tension stated by the manufacturerof the pulling device or 10,000 pounds, whichever is less. Do notuse metallic shielding wires, tapes or braids, or armor notdesigned for the purpose, in pulling tension calculations. Themaximum tension allowed for the conductors are computed asfollows:

Single Conductor:

T = S * A

Multiple Conductors:

T = N * S * A for 3 or less conductors

T = (0.8) * N * S * A for more than 3 conductors

where:T = conductor tension, lbsS = conductor stress, lbs/cmil (Table 22)A = conductor area, cmil (Table 23)N = number of conductors


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Pulling different conductor sizes at the same time is notrecommended if the conductor size or other cable characteristicsare significantly different. If different size conductors must bepulled, it must be done with care.

Table 22: Maximum Allowable Conductor Stress

Cable Type Material Temper lbs/cmil

All Copper soft 0.008

Power Aluminum Hard 0.008

Power Aluminum 3/4 hard 0.006

Power Aluminum AA-8000 0.006

URD Aluminum 1/2 hard 0.003

Solid Aluminum Soft 0.002

Table 23: Concentric Stranded Copper & Aluminum Conductor Area

AWG cmil AWG cmil

14 4,110 250 250,00012 6,530 300 300,00010 10,380 350 350,0008 16,510 400 400,0006 26,240 450 450,0004 41,740 500 500,0003 52,620 600 600,0002 66,360 700 700,0001 83,690 750 750,000

1/0 105,600 800 800,0002/0 133,100 900 900,0003/0 167,800 1000 1,000,0004/0 211,600 1200 1,200,000


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10.1.2 Pulling Tension Calculation

The following equations allow the user to calculate the expectedpulling tension of a conductor in a conduit pull.

Tin=W×L×

where; Tin = tension, lbs.W = weight of one foot of cable, lbs.L = length of pull, ft. = coefficient of friction for the particular duct

material and outer layer of the cable.

The weight of the cable and the length of the pull can bedetermined with great accuracy. The one variable that variestremendously is the value of the coefficient of friction—it canvary from 0.05 to 1.0.

Even when the materials used in the duct and jacket are known,the type and amount of lubricant can be an important factor inthis variation.

10.1.3 Coefficient of Friction

The coefficient of dynamic friction (μ) is a measure of thefriction between a moving conductor and the conduit. Thecoefficient of friction can have a large impact on the tensioncalculation.

Table 24: Typical Coefficients of Dynamic Friction (μ) for Cables withan Adequate Cable Lubrication During a Pull

Cable Outer Jacket or Insulation Conduit Type

EMT PVCType THHN/THWN (Nylon) 0.28 0.24

Type XHHW, USE, RHH/RHW (XLPE) 0.25 0.14


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TriangularCradled

D

10.1.4 Conductor Configuration

The configuration of three single-conductors in a conduit isdetermined by the ratio of the conduit inner diameter (D) to theouter diameter (d) of one of the single conductors (D/d ratio).

Figure 8: Configuration of Three Single Conductors

A cradled configuration develops when three single-conductorsare pulled into a conduit where the D/d ratio is 2.5 or greater. Atriangular configuration develops when three single-conductorsare pulled into a conduit where the D/d ratio is less than 2.5.

10.1.5 Weight Correction Factor

This configuration of conductors can affect the tension. A weightcorrection factor (ω) is used in the tension equations to account for this effect. This is given by the following equations:

Single Conductor: = 1

Three Conductor (Triangular):

Three Conductor (Cradled):

Dd < 2.5

Dd ≥ 2.5


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Four Conductors or More

To be conservative, it is recommended that the three-conductor(triangular) factor be used when pulling two conductors.

10.1.6 Tension Formulas

Horizontal Straight Section:Tout = WL+Tin

Inclined and Vertical Section:

Pulling up:Tout = WL(sin + cos) + Tin (lbs)

Pulling Down:Tout = WL(sin + cos) + Tin (lbs)

Elbows and Bends (approximation):Tout = Tin e

where; Tout = tension out of a section, lbsTin = tension into a section, lbsW = total cable weight, lbs/ftL = straight section length, ft = coefficient of dynamic friction

= weight correction factor

= straight section angle from horizontal,radians

= bend section angle, radianse = 2.71 natural logarithm base


68

10.1.7 Conductor Jamming

There is a tendency where cables may jam against the inside ofthe conduit when the diameter of each cable is about one-thirdthe inner diameter of the duct. This commonly occurs when thecables go around a bend or a series of bends. Jamming increasesthe pulling tension to a point that it can damage the cable. Thus,the jam ratio of the cables needs to be evaluated. The equationfor the jam ratio of three cables in a duct is as follows:

where; 1.05 factor to account the possible ovality of theconduit in a bend and for the cable of havinga slightly different diameter at any point

D = inside diameter of the duct or conduitd = outer diameter of each of the three cables

When the jam ratio falls between 2.6 and 3.2, jamming isprobable if there are bends in the run. Thus, to avoid possibleproblem with conductor jamming, it is advisable to avoid pullswhere the jam ratio is between 2.6 and 3.2.

10.2 Sidewall Pressure

Sidewall pressure is the vector force that exists on the cable as it ispulled through a bend. Because the surface area of the bend issmaller in small radius bends, that force is concentrated over a muchsmaller area. Most of the time sidewall pressure is the limiting factorin a cable pull. It is calculated by the following equations:

Single-conductor cable or multiple-conductor cable under commonjacket:

Dd

Jam ratio = 1.05


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Three Conductor (Triangular):

Three Conductor (Cradled):

where; Sp = sidewall pressure, lbs/ftT = tension coming out of the bend, lbs = weight correction factorR = bend radius, ft

Table 25: Sidewall Bearing Pressure Limits

Cable Type SWBP, lbs/ftInstrumentation 100600 V non-shielded control 300600 V power 5005 to 15 kV shielded power 50025 to 46 kV power 300

10.3 Bending Radius

The following are the minimum values for the radii to whichinsulated cables may be bent during installation. These limits do notapply to conduit bends, sheaves or other curved surfaces aroundwhich the cable may be pulled under tension while being installed.Larger radii bends may be required for such conditions to limit


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sidewall pressure. In all cases the minimum radii specified refers tothe inner surface of the cable and not to the axis of the cable.

The minimum bending radii for both single and multiple-conductorcable with or without lead sheath and without metallic shielding orarmor are as follows:

Table 26: Minimum Bending Radii for Power and Control Cableswithout Metallic Shielding or Armor

Thickness ofConductorInsulation,

inches

Overall Diameter of cables, inches

1.000 and less 1.001 to 2.0002.001and

largerMinimum Bending Radius asMultiple of Cable Diameter

0.156 andless

4 5 6

0.157 to0.315

5 6 7

0.316 andover

- 7 8

Source: Okonite


71

Table 27: Minimum Bending Radii for Power and Control Cables withMetallic Shielding or Armor, as Multiple of Cable Diameter

Type of Cable Power Control

Armored, flat tape or wire type 12... 12...

Armored, smooth aluminum sheath, up to; . .

...0.75 inches cable diameter 10*. 10*.

...0.76 to 1.5 inches cable diameter 12... 12...

...over 1.5 inches cable diameter 15... 15...

Armored, corrugated sheath or . .

...interlocked type 7... 7...

...with shielded single conductor 12... 12...

...with shielded multi-conductor **... **...

Non-armored, flat or corrugated . .

...tape shielded single conductor 12... 12...

...tape shielded multi-conductor **... **...

...multi-conductor overall tape shield 12... 12...

...LCS with PVC jacket 15... 15...

Non-armored, concentric neutral 8... —...

Non-armored, flat strap shielded 8... —...

Non-armored, wire shielded ***.. —...

* with shielded conductors 12

** 12 times single conductor diameter

or 7 times overall cable diameter — whichever is greater

*** See Power and control cables without metallic shielding

LCS = longitudinally applied corrugated shield

Source: Okonite


72

11. PACKAGING

The usual cut for small diameter building wires is 150 meter and ispackaged in boxes. However, for bigger diameter wires and powercables, these usually come in 300 meter rolls. For special and othercutting or packaging requirements, this has to be specified andcoordinated with the wires and cables manufacturer.

12. CABLE/WIRE APPLICATION

In ordering wires/cables, it is important that the manufacturer knows theintended application of the wires/cables. This in order that they canrecommend the type of cable best suited for the application. The usualservice conditions for cables are indoor/outdoor application in wet, damp,and/or dry environment. However, for cables that are to be used in specialapplication or condition, this has to be communicated to the manufacturer.

13. CABLE INSTALLATION METHOD

Knowledge of the cable installation method to be used is important for themanufacturer since the current carrying capacity of the cable will dependon where the cables are to be laid such as in open air, raceway, cable tray,conduit or directly buried. This is due to the heat generated by the cablesdue to their close proximity and the capability of the type of cableinstallation to dissipate this generated heat. Per Philippine ElectricalCode (PEC), certain de-rating factor has to be applied depending on theparticular installation method.

14. COLOR CODING

In accordance with the PEC, certain color coding is required forconductors of a multi-core cable. Ground conductors shall have acontinuous white, white stripe or gray outer finish. On the other hand, livewires can have any color, except the foregoing.

Equipment grounding conductor, however, shall have a continuous greencolor or a continuous green color with one or more yellow stripes.


73

For jacketed cords furnished with appliances, one conductor having itsinsulation colored light blue, with the other conductors having theirinsulation of a readily distinguishable color other than white or gray.

For electric space-heating cables, the lead wire shall have the followingcolor identification to indicate the circuit voltage on which it is to be used:

(1) 115 volt, nominal – yellow(2) 208 volt, nominal – blue(3) 230 volt, nominal – red(4) 265 volt, nominal – brown(5) 460 volt, nominal - orange

15. REFERENCE STANDARDS

Wires and cables are usually made to comply with certain referencestandard (e.g. Philippine National Standard (PNS), IEC, ASTM, ICEA,AIEC, NEMA, UL, etc.) Some PNS on wires and cables are listed inAnnex C.

16. STORAGE

Another important consideration or information needed to becommunicated to the wire manufacturer/supplier is the storage of the cableat site, whether it will be stored indoor or outdoor. If the cable will bestored outdoor and subjected to the elements, depending on the cableinsulation or construction and the sealing of its terminals, the cableperformance may be degraded. Likewise, for power conductors onreels, especially when it is expected to be stored outdoors forextended periods, special attention should also be taken on the material ofthe cable reel. Should the reels be made of wood, the reel may rot aftersome time making it difficult to transport the cable to another site.


74

Hereunder are some use and storage suggestions:

(1) Upon receipt, cable protective covering should be thoroughlyscrutinized for possible signs of damage during delivery. Ifevidence of damage is found, inform the carrier immediately.

(2) During unloading, make sure that theequipment used does not have contactwith the cable surface and itsprotective covering. When a crane isbeing used, a cradle supporting the reelflanges or a shaft through the arborhole should be used. If unloading isbeing done with the use of a forklift,the forks must lift the reel at 90° to theflanges and must be long enough toreach both flanges. The fork must notmake contact with the cable surface orthe cable protective covering.

(3) If an inclined ramp is used duringunloading, the ramp must be wideenough to have contact with bothflanges. When controlling the decentof the reel, it should be done throughthe use of the reel flanges and not thesurface of the cable.

(4) The reels should not be dropped fromthe delivering vehicle to the groundwhatever the circumstance.

(5) The weight of the reel and cable mustbe allowed to rest on the flanges,which, in turn, should be resting on ahard surface to prevent the flangesfrom sinking and shifting part of saidweight to the cables.


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(6) Reels should be stored in an area where no falling debris ofconstruction material or other objects that can damage the cable.

(7) Cable should not be stored in an area where chemicals orpetroleum can be spilled or sprayed on the cable.

(8) Reels of cable with unjacketed sheath or armor (aluminum orsteel) should be stored indoors. Unjacketed sheath or armor easilycorrodes when exposed outside.

(9) Care must be taken when a reel of cable is rolled from one point toanother, see to it that there are no objects on the surface areawhich could have contact and damage the cable surface or itsprotective covering.

(10)Keep cable away from open fires or sources of heat.

(11)Cable ends must always be sealed to prevent the entrance ofmoisture.

17. AVAILABLE CABLE HANDLING EQUIPMENT AT SITE

It will be important for the cable and wire manufacturer/supplier to knowwhether there will be any cable handling equipment available at site so thatthey can prepare the means to unload the cables safely from the transportvehicle.

If a cable handling equipment is available at site, its capacity has to becommunicated to the manufacturer/supplier so as to ensure that it iscapable of handling the weight of the cable.

18. SAFEGUARDS FOR INSTALLING WIRES AND CABLESIN CONDUIT

Investigations have shown that cable failures often can be attributed todamage caused during installation due to carelessness, inexperience andinability to observe certain simple precautions. In order to eliminate suchpreventable causes of electrical shutdowns and loss of production, thefollowing procedures should be followed:


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18.1 Before Pulling Wire/Cable

(1) Know and observe all Philippine Electrical Code rulesregarding installation.

(2) Check the conduit and wire/cable sizes and actual overalldiameters in order to be sure that the approved "fill" will notbe exceeded. Do not "crowd" the conduit.

(3) Check the type of wire/cable to be installed.(4) Consider the use of larger conduits or additional pull boxes.(5) Check any obstruction on the conduit.(6) To loosen any burrs, pull a short mandrel or plug closely

approximating the diameter of the conduit and clean out anyremaining dirt or foreign matter, follow it up with a swab.

18.2 While Pulling Wire/Cable

(1) To prevent short bends, sharp edges and "crossover", alwayshave a man feed wire straight into a conduit by hand or over alarge diameter sheave for large conductors/cables.

(2) Remove all lashings used for temporary bunching ofindividual wires/cables before they enter the conduit.

(3) Lead-out wires at all pull boxes and conduits. Feed them inagain for the next run.

(4) Never pull directly around short right angled bends.

18.3 After Pulling Wire/Cable

Shut off the exposed ends of the excess wire/cable on the reel with atape to prevent moisture from entering the wire/cable.

19. SAFEGUARD FOR SWITCHBOARD AND SIMILAR OPENWIRING

To avoid cutting or deforming the insulation at the contact point use widetape or straps with rounded edges instead of narrow strings when bindinggroups of wires, especially non-braided wires.


77

20. WIRE/CABLE ORDERING FORM

In order to guide the user, electrical designer or the purchaser incorrectly ordering or specifying the cable or wire that is needed for hisspecific use and for the wire and cable manufacturer/supplier to have thenecessary information to know the specific needs of his customer so that hecan give a correct price quotation, a wire/cable ordering form has beendeveloped in Annex D.


78

79

ANNEXES


81

ANNEX A

Table A1. Conductor Types and Sizes for 115/230-Volt, 3-Wire,Single-Phase Dwelling Services and Feeders. Conductor Types RHH,RHW, RHW-2, THHN, THHW, THW, THW-2, THWN, THWN-2,XHHW, XHHW-2, SE, USE, USE-2

Conductor mm2 Service or FeederRating (Amperes)

Copper Aluminum

22303038

506080100

125175200

30385060

80100125150

175250325

100110125150

175200225250

300350400


82

Table A2. Ampacities of Not More Than Three Single InsulatedConductors, Rated 0 Through 2 000 Volts, Supported on aMessenger, Based on Ambient Air Temperature of 40°C

ConductorSizemm2

Temperature Rating of Conductor (See Table 3.10.1.13.)75°C 90°C 75°C 90°CTypeRH,

RHW,THHW,THW,

THWN,XHHW,

ZW

TypesTHHN, THHW,

THW-2, THWN-2,RHH, RWH-2,

USE-2, XHHW-2,ZW-2

TypesRH, RHW,

THHW, THW,THWN, ZHHW

TypeTHHN, THHW,RHH, XHHW,

RHW-2, XHHW-2,THW-2, THWN-2,

USE-2, ZW-2COPPER ALUMINUM

125150175200250

316363390416496

369423460486581

248285310327392

288331360382458

325375400500

576630659741

674740771870

458505529606

535590617709

Table A3. Ampacities of Insulated Single Copper Conductor CablesTriplexed in Air Based on Conductor Temperatures of 90°C and105°C and Ambient Air Temperature of 40°C

ConductorSizemm2

Temperature Rating of Conductor(See Table 3.10.1.61)

2 001–5 000 VoltsAmpacity


90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType

MV-105125175250375400500

370460580740770870

410510640825860970

375465580720750840

420520650810845940


83

Table A4. Ampacities of Insulated Single Aluminum ConductorCables Triplexed in Air Based on Conductor Temperatures of 90°Cand 105°C and Ambient Air Temperature of 40°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType

MV-105125175250375400500

290360460595620705

320400510660685790

295365460585605690

330410515655680770

Table A5. Ampacities of Insulated Single Copper Conductor Isolatedin Air Based on Conductor Temperatures of 90°C and 105°C andAmbient Air Temperature of 40°C

ConductorSizemm2


2 001–5 000Volts

Ampacity

5 001–15 000Volts

Ampacity

15 001–35 000Volts

Ampacity90°CTypeMV-

90

105°CTypeMV-105

90°CTypeMV-

90

105°CTypeMV-105

90°CTypeMV-

90

105°CTypeMV-105

125175250375400500

435545695890925

1 060

485605775990

1 0301 185

435545685875910

1 050

485600765980

1 0201 030

430540680860895

1 030

480595755960

1 0001 145


84

Table A6. Ampacities of Insulated Single Aluminum ConductorIsolated in Air Based on Conductor Temperatures of 90°C and105°C and Ambient Air Temperature of 40°C

ConductorSizemm2


2 001–5 000Volts

Ampacity

5 001–15 000Volts

Ampacity

15 001–35 000Volts

Ampacity90°CTypeMV-

90

105°CTypeMV-105

90°CTypeMV-

90

105°CTypeMV-105

90°CTypeMV-

90

105°CTypeMV-105

125175250375400500

340425545700730845

380475605780815940

340425535690720830

380475600770805930

340425530680705815

375470590755790910

Table A7. Ampacities of an Insulated Three-Conductor CopperCable Isolated in Air Based on Conductor Temperatures of 90°Cand 105°C and Ambient Air Temperature of 40°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType

MV-105125175250375400500

315390485610635695

350435545680705780

355430535665690760

395485600735765850


85

Table A8. Ampacities of an Insulated Three-Conductor AluminumCable Isolated in Air Based on Conductor Temperatures of 90°Cand 105°C and Ambient Air Temperature of 40°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType

MV-10512575250375400500

250305385490510575

280340430545565640

280340425535555625

315380475595615695

Table A9. Ampacities of an Insulated Triplexed or Three Single-Conductor Copper Cables in Isolated Conduit in Air Based onConductor Temperatures of 90°C and 105°C and Ambient AirTemperature of 40°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType

MV-105125175250375400500

310380475595615680

350425530660685760

325390480580600665

360435535650675745


86

Table A10. Ampacities of an Insulated Triplexed or Three Single-Conductor Aluminum Cables in Isolated Conduit in Air Based onConductor Temperatures of 90°C and 105°C and Ambient AirTemperature of 40°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType

MV-105125175250375400500

250300380485505570

280335425540560635

255305385480500555

290345430535555630

Table A11. Ampacities of an Insulated Three-Conductor CopperCable in Isolated Conduit in Air Based on Conductor Temperaturesof 90°C and 105°C and Ambient Air Temperature of 40°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType

MV-105125175250375400500

275345425520540580

310385475580600650

310380470565585640

345425525630655715


87

Table A12. Ampacities of an Insulated Three-Conductor AluminumCable in Isolated Conduit in Air Based on Conductor Temperaturesof 90°C and 105°C and Ambient Air Temperature of 40°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType

MV-105125175250375400500

215270340425440500

240300380475495550

245300380465485540

275335425515535605


88

Table A13. Ampacities of Three Single-Insulated CopperConductors in Underground Electrical Ducts (Three Conductors perElectrical Duct) Based on Ambient Earth Temperature of 20°C,Electrical Duct Arrangement per Figure 3.10.1.60, 100 Percent LoadFactor, Thermal Resistance (RHO) of 90, Conductor Temperaturesof 90°C and 105°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType

MV-105One Circuit (See Figure 3.10.1.60, Detail 1.)

125175250375400500

315380470580600660

340410505625650710

320385465560580630

340410500605630680

Three Circuits (See Figure 3.10.1.60, Detail 2.)125175250375400500

255310375455475520

275330405490510555

255305370435454490

275325395470490530

Six Circuits (See Figure 3.10.1.60, Detail 3.)125175250375400500

205245300360375405

220265325390405440

205240290345360385

220260310370385410


89

Table A14. Ampacities of Three Single-Insulated AluminumConductors in Underground Electrical Ducts (Three Conductors perElectrical Duct) Based on Ambient Earth Temperature of 20°C,Electrical Duct Arrangement per Figure 3.10.1.60, 100 Percent LoadFactor, Thermal Resistance (RHO) of 90, Conductor Temperaturesof 90°C and 105°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType


125175250375400500

245300370465485535

265320400500520580

245300370450470520

265325400485505555


200240295365380420

215260320390405455

195240290350365400

215255315380395435


160190240285295330

175205255310325355

160195230275285315

170205250300315340


90

Table A15. Ampacities of Three Insulated Copper ConductorsCabled Within an Overall Covering (Three-Conductor Cable) inUnderground Electrical Ducts (One Cable per Electrical Duct)Based on Ambient Earth Temperature of 20°C, Electrical DuctArrangement per Figure 3.10.1.60, 100 Percent Load Factor,Thermal Resistance (RHO) of 90, Conductor Temperatures of 90°Cand 105°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType


125175250375400500

285350430525545590

310375460565585635

305370450540560605

330395485580600650


240290355425440480

260310380460480515

250300360425440480

265320385460480510


195235290345360385

215265310370385415

200240290335350375

215270305360375400


91

Table A16. Ampacities of Three Insulated Aluminum ConductorsCabled Within an Overall Covering (Three-Conductor Cable) inUnderground Electrical Ducts (One Cable per Electrical Duct)Based on Ambient Earth Temperature of 20°C, Electrical DuctArrangement per Figure 3.10.1.60, 100 Percent Load Factor,Thermal Resistance (RHO) of 90, Conductor Temperatures of 90°Cand 105°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType


125175250375400500

225275340420435490

240305365455475530

240290355435450505

260310385470490535


185225280340355395

200245300370385425

195235285345360395

210250305370385425


155185230275285315

165200245300315340

155190230270280310

165200245290300330


92

Table A17. Ampacities of Single Insulated Copper ConductorsDirectly Buried in Earth Based on Ambient Earth Temperature of20°C, Arrangement per Figure 3.10.1.60, 100 Percent Load Factor,Thermal Resistance (RHO) of 90, Conductor Temperatures of 90°Cand 105°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType

MV-105One Circuit, Three Conductors (See Figure 3.10.1.60, Detail 9.)

125175250375400500

460560690835870970

500610745900940

1 045

430530650795830920

465570700855890995

Two Circuits, Six Conductors (See Figure 3.10.1.60, Detail 10.)125175250375400500

425510630765800880

460550680825860950

405490600730760845

430525645785820910


93

Table A18. Ampacities of Single Insulated Aluminum ConductorsDirectly Buried in Earth Based on Ambient Earth Temperature of20°C, Arrangement per Figure 3.10.1.60, 100 Percent Load Factor,Thermal Resistance (RHO) of 90, Conductor Temperatures of 90°Cand 105°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType


125175250375400500

365440540660685770

390475580710740830

340410510630655730

365445545670700785


355405495605630700

360435530650675775

315380470575595670

340410505620645720


94

Table A19. Ampacities of Three Insulated Copper ConductorsCabled Within an Overall Covering (Three-Conductor Cable),Directly Buried in Earth Based on Ambient Earth Temperature of20°C, Arrangement per Figure 3.10.1.60, 100 Percent Load Factor,Thermal Resistance (RHO) of 90, Conductor Temperatures of 90°Cand 105°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType


125175250375400500

360435530640670720

390470570690720775

375455550660685740

405490590710740800

Two Circuits, (See Figure 3.10.1.60, Detail 6.)125175250375400500

335405490590610655

340435525635660705

325415500600625665

350445535645670720


95

Table A20. Ampacities of Three Insulated Aluminum ConductorsCabled Within an Overall Covering (Three-Conductor Cable),Directly Buried in Earth Based on Ambient Earth Temperature of20°C, Arrangement per Figure 3.10.1.60, 100 Percent Load Factor,Thermal Resistance (RHO) of 90, Conductor Temperatures of 90°Cand 105°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType


125175250375400500

280340420515535590

305370450555575640

295355435535555610

315385470575595655

Two Circuits, (See Figure 3.10.1.60, Detail 6.)125175250375400500

260315385475495540

280340415510530580

270325395480500550

290350425520540590


96

Table A21. Ampacities of Three Triplexed Single Insulated CopperConductors Directly Buried in Earth Based on Ambient EarthTemperature of 20°C, Arrangement per Figure 3.10.1.60, 100Percent Load Factor, Thermal Resistance (RHO) of 90, ConductorTemperatures 90°C and 105°C

ConductorSizemm2




90°C TypeMV-90

105°CType

MV-10590°C Type

MV-90

105°CType


125175250375400500

405485590715745815

435570635770805875

385465565675705760

405500605730760820


365440535640670730

390475575690720785

350420510610635680

375450545655680735


97

Table A22. Ampacities of Three Triplexed Single InsulatedAluminum Conductors Directly Buried in Earth Based on AmbientEarth Temperature of 20°C, Arrangement per Figure 3.10.1.60, 100Percent Load Factor, Thermal Resistance (RHO) of 90, ConductorTemperatures 90°C and 105°C

Conductor

Sizemm2




90°CType

MV-90

105°CType

MV-105

90°CType

MV-90

105°CType


125175250375400500

315380465575595660

345415500620645715

300365445545565625

320395480585605670


285345420515535590

305370455555575635

275330405480500555

295450435520540595


98

Table A23. Minimum Wire-Bending Space at Terminals

Wire Sizemm2

Wires per Terminal1 2 3 4 or more

mm mm mm mm125150175200250325375400

215d

250e

305e

330e

350e

380e

405e

430e

(50)(75)(75)(75)(75)(75)(75)(75)

215d

250d

305e

330e

350e

400e

460e

480e

(50)(50)(50)(75)(75)(75)(75)(75)

230b

280b

330e

350e

380e

455e

510e

560e

(25)(25)(25)(75)(75)(75)(75)(75)

250300350d

380e

400e

480e

560e

610e

(75)(75)(75)(75)(75)

1. Bending space at terminals shall be measured in a straight line from the end of thelug or wire connector in a direction perpendicular to the enclosure wall.

2. For removable and lay-in wire terminals intended for only one wire, bending spaceshall be permitted to be reduced by the following number of millimeters:

a 13 mmb 25 mmc 40 mmd 50 mme 75 mm

3. This column shall be permitted to determine the required wire-bending space forcompact stranded aluminum conductors in sizes up to 500 mm2 and manufactured usingAA-8000 series electrical grade aluminum alloy conductor material in accordance with3.10.1.14.


99

Table A24. Full-Load Current, Three-Phase Alternating-CurrentMotorsThe following values of full-load currents are typical for motors running at speeds usual for beltedmotors and motors with normal torque characteristics.

The voltages listed are rated motor voltages. The currents listed shall be permitted for systemvoltage ranges of 220 to 240, 380 to 415, and 440 to 480 volts.

Horsepower

Induction-Type SquirrelCage and Wound Rotor

(Amperes)Synchronous-Type UnityPower Factor* (Amperes)

230Volts

400Volts

460Volts

230Volts

400Volts

460Volts

½¾1

1½235

7½

2.23.24.26.06.89.615.222

1.31.82.33.34.36.19.714

1.11.62.13.03.44.87.611

————————

————————

————————

101520253040

2842546880104

182734445166

142127344052

———536383

———

33.640.852

———263241

506075100125150200

130154192248312360480

83103128165208240320

657796

124156180240

104123155202253302400

66.481.6104

134.4168

201.3268

526178

101126151201

250300350400450500

——————

403482560636711786

302361414477515590

——————

——————

——————

*For 90 and 80 percent power factor, the figures shall be multiplied by 1.1 and 1.25,respectively.


100

Table A25. Conversion Table of Polyphase Design B, C, and DMaximum Locked-Rotor Currents for Selection of DisconnectingMeans and Controllers as Determined from Horsepower andVoltage Rating and Design LetterFor use only with 4.30.9.10, 4.40.2.2, 4.40.5.1 and 4.55.1.8(c).

RatedHorsepower

Maximum Motor Locked-Rotor Current in Amperes,Two- and Three-Phase, Design B, C, and D*

230 Volts 400 volts 460 VoltsB, C, D E B, C, D E B, C, D E

½¾1

1½235

7½

20253040506492

127

202530405073122183

12.14.516.52232415981

1214.516.52232

46.578

116.5

1012.51520253246

63.5

1012.5152025

36.561

91.5101520253040

162232290365435580

225337449562674824

104.5149.5183237278

368.5

145.5217.5283.5364430523

81116145183218290

113169225281337412

506075100125150200

72587010851450181521702900

1030123615451873234128093745

463.558272496512111447

1933.5

65882710311247

1561.51873.52497.5

36343554372590810851450

515618773937117114051873

250300350400450500

——————

——————

2435.52937.53449.538674487

4829.5

31283750.54433

4993.55818

6237.5

182522002550290032503625

234428093277374542144682

*Design A motors are not limited to a maximum starting current or locked rotorcurrent.


101

Table A26 Ampacities of Two or Three Insulated Conductors,Rated 0 through 2000 Volts, Within an Overall Covering(Multiconductor Cable), in Raceway in Free Air Based on AmbientAir Temperature of 30ºC

Conductor Size

mm2

Temperature Rating of Conductor. See Table 3.10.1.13600C 750C 900C 600C 750C 900C

TypesTW,UF

TypesRH,

RHW,THHW,THW,

THWN,XHHW,

ZW

TypesTHHN,THHW,THW-2,

THWN-2,RHH,

RHW-2,USE-2,XHHW,

XHHW-2,ZW-2

TypesTW

TypesRH,

RHW,THHW,THW,

THWN,XHHW

TypesTHHN,THHW,THW-2,

THWN-2,RHH,

RHW-2,USE-2,XHHW,

XHHW-2,ZW-2

COPPER ALUMINUM

125150175200250

205234250274315

245281300328378

276317340371427

160185199218254

192221238261303

217250270295342

*Unless otherwise specifically permitted elsewhere in this Code, the overcurrent protection forthese conductor types shall not exceed 15 amperes for 2.0 mm2 (1.6 mm dia.), 20 amperes for 3.5mm2 (2.0 mm dia.), and 30 amperes for 5.5 mm2 (2.6 mm dia.) copper; or 15 amperes for 3.5 mm2

(2.0 mm dia.) and 25 amperes for 5.5 mm2 (2.6 mm dia.) aluminum and copper-clad aluminum.


102

Table A27. Ampacities of Multiconductor Cables with Not Morethan Three Insulated Conductors, Rated 0 Through 2000 Volts, inFree Air Based on Ambient Air Temperature of 40ºC (For TypesTC, MC, MI, UF, and USE Cables)

Conductor Sizemm2

Temperature Rating of Conductor. See Table 3.10.1.13.600C 750C 850C 900C 600C 750C 850C 900C

COPPER ALUMINUM125150175200250

212237257281321

274306332363416

305341371406465

320357388425487

166186202222255

214240261287330

239268292317368

250280304334385

*Unless otherwise specifically permitted elsewhere in this Code, the overcurrent protection forthese conductor types shall not exceed 15 amperes for 2.0 mm2 (1.6 mm dia.), 20 amperes for 3.5mm2 (2.0 mm dia.), and 30 amperes for 5.5 mm2 (2.6 mm dia.) copper; or 15 amperes for 3.5 mm2

(2.0 mm dia.), and 25 amperes for 5.5 mm2 (2.6 mm dia.) aluminum and copper-clad aluminum.

Table A28. Ampacities of Single Insulated Conductors, Rated 0 through 2000 Volts, in NonmagneticUnderground Electrical Ducts (One Conductor per Electrical Duct), Based on Ambient EarthTemperature of 20ºC, Electrical Duct Arrangement per Figure B-310-2, Conductor Temperature75ºC

ConductorSize

(mm2)

3 Electrical Duct(Fig. B-310-2,

Detail 2)

6 Electrical Duct

(Fig. B-310-2,Detail 3)


Detail 4)


Detail 2)


Detail 3)


Detail 4)

TypesRHW, THHW,THW, THWN,XHHW, USE






COPPER ALUMINUMRHO

60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

125175250400

410503624794

344418511640

327396484603

386472583736

295355431534

275330400494

369446545674

270322387469

252299360434

320393489626

269327401505

256310379475

302369457581

230277337421

214258313389

288350430538

211252305375

197235284347

10

3

Po

wer

Cab

les&

Wires

Tech

nical

Man

ual

Table A29. Ampacities of Three Insulated Conductors, Rated 0 through 2000 Volts, Within an OverallCovering (Three-Conductor Cable) in Underground Electrical Ducts (One Cable per Electrical Duct)Based on Ambient Earth Temperature of 20ºC, Electrical Duct Arrangement per Figure B-310-2,Conductor Temperature 75ºC

ConductorSize

(mm2)

1 Electrical Duct(Fig. B-310-2, Detail 1)












COPPER ALUMINUM

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

125175250400500

297363444552628

265321389478539

256310375459518

280340414511579

222267320388435

209250299362405

258312377462522

184219261314351

169202240288321

233285352446521

207252308386447

201244297372430

219267328413480

174209254314361

163196237293336

505245299374433

144172207254291

132158190233266

10

4

Po

wer

Cab

les&

Wires

Tech

nical

Manu

al

Table A30. Ampacities of Three Single Insulated Conductors, Rated 0 Through 2000 Volts, inUnderground Electrical Ducts (Three Conductors per Electrical Duct) Based on Ambient EarthTemperature of 20ºC, Electrical Duct Arrangement per Figure B-310-2, Conductor Temperature 75ºC

ConductorSizemm2







TypesRHW, THHW, THW,THWN, XHHW, USE






COPPER ALUMINUM

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

RHO60LF50

RHO90LF100

RHO120LF100

125150175200

334373409442

290321351376

279308337361

310344377394

236260283302

220242264280

281310340368

192210228243

176192209223

261293321349

227252276297

218242265284

242272296321

185204222238

172190207220

220245266288

150165179191

137151164174

105

Pow

erC

ables&

Wires

Tech

nicalM

anu

al


106

Table A31. Ampacities of Two or Three Insulated Conductors,Rated 0 Through 2000 Volts, Cabled Within an Overall (Two- orThree-Conductor) Covering, Directly Buried in Earth, Based onAmbient Earth Temperature of 20ºC, Arrangement per FigureB-310-2, 100 Percent Load Factor, Thermal Resistance (Rho) of 90

ConductorSizemm2

1 Cable(Fig. B-310-2,

Detail 5)


Detail 6)


Detail 5)


Detail 6)600C 750C 600C 750C 600C 750C 600C 750C

TypesUF

TypesRHW,

THHW,THW,

THWN,XHHW,

USE

TypesUF

TypesRHW,

THHW,THW,

THWN,XHHW,

USE

TypesUF

TypesRHW,

THHW,THW,

THWN,XHHW,

USE

TypesUF

TypesRHW,

THHW,THW,

THWN,XHHW,

USE

COPPER ALUMINUM

125175250400500

—————

333401481585657

—————

308370442535600

—————

261315381473545

—————

241290350433497

Note: For ampacities of Type UF cable in underground electrical ducts, multiply theampacities shown in the table by 0.74.


107

Table A32. Ampacities of Three Triplexed Single InsulatedConductors, Rated 0 Through 2000 Volts, Directly Buried in EarthBased on Ambient Earth Temperature of 20ºC, Arrangement perFigure B-310-2, 100 Percent Load Factor, Thermal Resistance (Rho)of 90

ConductorSizemm2

See Fig. B-310-2,Details 7




600C 750C 600C 750C 600C 750C 600C 750CTYPES TYPES

UF USE UF USE UF USE UF USECOPPER ALUMINUM

125175250400500

—————

370445436654744

—————

336403483587665

—————

289349424525608

—————

263316382471544

Table A33. Ampacities of Three Single Insulated Conductors, Rated0 Through 2000 Volts, Directly Buried in Earth Based on AmbientEarth Temperature of 20ºC, Arrangement per Figure B-310-2, 100Percent Load Factor, Thermal Resistance (Rho) of 90

ConductorSizemm2

See Fig. B-310-2,Detail 9




600C 750C 600C 750C 600C 750C 600C 750CTYPES TYPES

UF USE UF USE UF USE UF USE

COPPER ALUMINUM

125175250400

————

429516626767

————

394474572700

————

335403490605

————

308370448552


108

Table A34. Maximum Number of Conductors and Fixture Wires inElectrical Metallic Tubing (Based on Table 9.1.1.1)

CONDUCTORS

TypeConductorSize [mm2

(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100

RH 2.0 (1.6)3.5 (2.0)

64

108

1613

2823

3931

6451

11290

169136

221177

282227

RHH,RHW, RHW-2

2.0 (1.6)3.5 (2.0)

43

76

119

2017

2723

4638

8066

120100

157131

201167

RH,RHH,RHW, RHW-2

5.5 (2.6)8.0 (3.2)

14

211

521

843

1375

1898

301613

532822

814234

1055544

1357056

223038

110

111

211

431

643

1075

17139

262013

342617

443322

506080

100

0000

1100

1111

1111

2211

4433

7655

111087

1513119

19171412

125150175200250

00000

00000

00000

11110

11111

11111

33322

55443

76654

98776

325375400500

0000

0000

0000

0000

1000

1111

1111

3221

4332

5443

TW 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

8652

151185

2519148

43332413

58453318

96745530

1681299653

25419514581

332255190105

424326243135

RHH*, RHW*,RHW-2*, THW,THHW, THW-2

2.0 (1.6) 6 10 16 28 39 64 112 169 221 282

RHH*, RHW*,RHW-2*, THHW,THW

3.5 (2.0)5.5 (2.6)

43

86

1310

2318

3124

5140

9070

136106

177138

227177

RHH*, RHW*,THW-2*, THW,THHW, THW-2

8.0 (3.2) 1 4 6 10 14 24 42 63 83 106

RHH*, RHW*,RHW-2*, TW,THW, THHW,THW-2

14223038

1111

3111

4321

8643

11864

1813107

32241712

48362618

63473424

81604431

506080

100

0000

1110

1111

2111

3321

6543

10976

1613119

20171512

26221916

125150175200250

00000

00000

11000

11111

11111

32111

54433

76654

108776

13111097

*Types RHH, RHW, and RHW-2 without outer covering.


109

Table A34. Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100


325375400500

0000

0000

0000

1000

1110

1111

2111

3332

4443

6554

THHN, THWN,THWN-2

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

129532

22161064

35261697

6145281612

8461382216

138101633626

2411761116446

3642661679669

47634721912691

608443279161116

223038

111

211

431

754

1075

16118

282015

433022

564029

715137

506080100

1000

1111

1111

3211

4332

7654

121087

19161311

25201714

32262218

125150175200250

00000

00000

11100

11111

11111

33211

65443

97665

1110986

151311108

325375400500

0000

0000

0000

1000

1111

1111

2111

4332

5443

7554

FEP, FEPB, PFA,PFAH, TFE

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

12963

2115116

34251810

60433118

81594224

134987040

23417112270

354258185106

462337241138

590430309177

142230

211

431

753

1296

17128

282013

503524

755336

986947

1268860

PFA, PFAH, TFE 38 1 1 2 4 6 9 16 25 33 42

PFA, PFAH,TFE, Z

506080100

1000

1111

1111

3321

5432

8654

141198

21171411

27221815

35292419

Z 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

1410643

25181175

412918118

7251312014

9869422719

161114704431

2822001227754

42630218511782

556394241153107

711504309195137

223038

111

311

532

964

1386

211310

372218

563428

744536

945746

XHH, XHHW,XHHW-2, ZW

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

8652

151185

2519148

43332413

58453318

96745530

1681299653

25419514581

332255190105

424326243135

*Types RHH, RHW, and RHW-2 without outer covering.


110


CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100


142230

111

321

643

1075

14107

221611

392820

604331

785640

1007251

XHH, XHHW,XHHW-2

38506080

100

11000

11111

11111

43211

54332

87654

15131097

2319161311

3025211714

3832272218

125150175200250

00000

00000

11100

11111

11111

33211

65443

98765

1210986

151311108

325375400500

0000

0000

0000

1000

1110

1111

2111

4332

5443

6554

FIXTURE WIRES

TypeConductorSize (mm2)

Raceway Size (mm)15 20 25 32 40 50

FFH-2, RFH-2, FHH-3 0.751.25

87

1412

2420

4134

5647

9278

SF-2, SFF-2 0.751.252.0

1087

181512

302520

524334

715847

1169678

SF-1, SFF-1 0.75 18 33 53 92 125 206RFH-1, RFHH-2, TF, TFF, XF,XFF

0.75 14 24 39 68 92 152

RFHH-2, TF, TFF, XF, XFF 1.25 11 19 31 55 74 123

XF, XFF 2.0 8 15 25 43 58 96TFN, TFFN 0.75

1.252217

3829

6348

10883

148113

244186

PF, PFF, PGF, PGFF, PAF,PTF, PTFF, PAFF

0.751.252.0

211612

362821

594634

1037960

14010881

231179134

HF, HFF, ZF, ZFF, ZHF 0.751.252.0

272014

473525

775641

1339872

18113398

298220161

KF-2, KFF-2 0.751.252.03.55.5

392719138

6948332315

11178543725

193136936443

2621851278758

43330520914496

KF-1, KFF-1 0.751.252.03.55.5

463322149

8257382516

13393634127

2301611087247

3132201489864

516362244161105

XF, XFF 3.55.5

43

86

1310

2318

3124

5140

Note: This table is for concentric stranded conductors only. For compact strandedconductors, Table A35 should be used.


111

Table A35. Maximum Number of Compact Conductors in ElectricalMetallic Tubing (Based on Table 9.1.1.1)

COMPACT CONDUCTORSType Conductor

Size (mm2)Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100THW,THW-2, THHW

8.014223038

21111

43211

65431

119653

1612974

262015118

4635261913

6953402921

9070523827

11589674934

506080

100

1000

1111

1111

3211

4332

7554

121087

18151311

23201714

30252118

125150175200250

00000

00000

11100

11111

11111

33211

55443

87665

119886

1412

11108

325375400500

0000

0000

0000

1000

1111

1111

2111

4332

5443

7554

THHN, THWN,THWN-2

8.014223038

—2111

—4311

—7432

—13864

—181186

—29181310

—52322317

—78483426

—102634534

—130815843

506080

100

1100

1111

1111

3321

5433

8765

1412108

22181512

29242016

37302521

125150175200250

00000

10000

11110

11111

11111

43321

65544

108765

13111097

161412119

325375400500

0000

0000

0000

1110

1111

1111

3221

4443

6553

7664

XHHW, XHHW-2

8.014223038

31111

54311

86432

1511864

20151186

3425181310

5944322317

9066483426

11787634534

149111815843

506080

100

1100

1111

1111

3321

5433

8765

1412108

22181513

29242017

37312521

125150175200250

00000

10000

11110

11111

21111

43321

76544

109876

13111097

171413119

325375400500

0000

0000

0000

1110

1111

1111

3221

4333

6554

8665

Definition: Compact stranding is the result of a manufacturing process where thestandard conductor is compressed to the extent that the interstices (voids between strandwires) are virtually eliminated.


112

Table A36. Maximum Number of Conductors and Fixture Wires in ElectricalNonmetallic Tubing (Based on Table 9.1.1.1)

CONDUCTORS

TypeConductor Size[mm2 (mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50RH 2.0 (1.6)

3.5 (2.0)43

87

1512

2721

3729

6149

RHH, RHW,RHW-2

2.0 (1.6)3.5 (2.0)

32

65

109

1916

2622

4336

RH,RHH, RHW,RHW-2

5.5 (2.6)8.0 (3.2)

14

111

411

733

1365

1797

291512

223038

100

111

211

431

643

975

506080

100

0000

0000

1111

1111

2111

4332

125150175200250

00000

00000

00000

11110

11111

11111

325375400500

0000

0000

0000

0000

1000

1111

TW 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

7541

131074

2217137

40312313

55423217

92715229

RHH*, RHW*,RHW-2*, THHW,THW, THW-2

2.0 (1.6) 4 8 15 27 37 61


3.5 (2.0)5.5 (2.6)

33

75

129

2117

2923

4938

RHH*, RHW*,RHW-2*, THHW,THW, THW-2

8.0 (3.2) 1 3 5 10 14 23


14223038

1110

2111

4321

7543

10864

171396

506080

100

0000

1100

1111

2111

3321

5543

125150175200250

00000

00000

10000

11111

11111

22111

325375400500

0000

0000

0000

0000

1110

1111

*Type RHH, RHW, and RHW-2 without outer covering.


113


CONDUCTORS


Raceway Size (mm)15 20 25 32 40 50

THHN, THWN,THWN-2

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

107421

1813853

32231586

5842261511

8058362115

13296603525

223038

111

111

421

753

965

15118

506080

100

0000

1110

1111

3211

4332

7544

125150175200250

00000

00000

11000

11111

11111

32211

325375400500

0000

0000

0000

1000

1110

1111

FEP, FEPB,PFA, PFAH,TFE

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

10753

181395

3123169

56412917

77564023

128936738

142230

111

421

643

1285

16118

271913

PFA, PFAH,TFE

38 1 1 1 4 5 9

PFA, PFAH,TFE, Z

506080

100

0000

1111

1111

3211

4432

7654

Z 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

128531

2215964

382716107

6848291813

9366402518

154109674230

223038

111

311

532

954

1276

201210


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

75411

1310743

22171375

403123139

5542321713

9271522921

2230

11

11

42

75

96

1511


114


CONDUCTORS


Raceway Size (mm)15 20 25 32 40 50

XHH, XHHW,XHHW-2

38 1 1 1 3 5 8506080

100

0000

1110

1111

3211

4332

7654

125150175200250

00000

00000

11100

11111

11111

33211

325375400500

0000

0000

0000

1000

1110

1111

FIXTURE WIRES

TypeConductor Size

(mm2)Raceway Size (mm)

15 20 25 32 40 50FFH-2, RFH-2, RFHH-3 0.75

1.2565

1210

2118

3932

5345

8874

SF-2, SFF-2 0.751.252.0

875

151310

272218

494032

675545

1119274

SF-1, SFF-1 0.75 15 28 48 86 119 197

RFH-1, RFHH-2, TF,TFF, XF, XFF

0.75 11 20 35 64 88 145

RFHH-2, TF, TFF, XF,XFF

1.25 9 16 29 51 71 117

XF, XFF 2.0 7 13 22 40 55 92

TFN, TFFN 0.751.25

1813

3325

5743

10278

141107

233178

PF, PFF, PGF, PGFF,PAF, PTF, PTFF, PAFF

0.751.252.0

171310

312418

544231

977556

13310377

221171128

HF, HFF, ZF, ZFF, ZHF 0.751.252.0

221612

402922

705138

1259268

17212793

285210154

KF-2, KFF-2 0.751.252.03.55.5

312215107

5841281913

10171493322

182128886040

2501761218355

41329120013892

KF-1, KFF-1 0.751.252.03.55.5

382618127

6949332214

12185573824

2171521026844

2982091419361

493346233154101

XF, XFF 3.55.5

33

75

129

2117

2923

4938



115

Table A37. Maximum Number of Compact Conductors in Electrical NonmetallicTubing (Based on Table 9.1.1.1)

COMPACT CONDUCTORS

TypeConductor Size


15 20 25 32 40 50THW, THW-2,THHW

8.014223038

11110

32111

64321

118643

1511864

251914107

506080100

0000

1110

1111

3211

4332

6544

125150175200250

00000

00000

11000

11111

11111

32211

325375400500

0000

0000

0000

1000

1110

1111

THHN, THWN,THWN-2

8.014223038

1111

4211

7432

12754

171075

2817129

506080100

1000

1111

1111

3321

5432

8654

125150175200250

00000

00000

11100

11111

11111

33221

325375400500

0000

0000

0000

1110

1111

1111

XHHW,XHHW-2

8.014223038

21111

43211

86432

1410754

19141075

322417129

506080100

1000

1111

1111

3321

5433

8754

125150175200250

00000

00000

11110

11111

11111

33321

325375400500

0000

0000

0000

1110

1111

1111



116

Table A38 Maximum Number of Conductors and Fixture Wires inFlexible Metal Conduit (Based on Table 9.1.1.1)

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100

RH 2.0 (1.6)3.5 (2.0)

65

108

1512

2419

3528

6250

9475

135108

184148

240193

RHH, RHW,RHW-2

2.0 (1.6)3.5 (2.0)

43

76

119

1714

2521

4437

6755

9680

131109

171142

RH, RHH,RHW,RHW-2

5.5 (2.6)8.0 (3.2)

14

311

521

743

1165

1797

301512

452319

643427

884637

1156048

223038

110

111

211

431

542

1075

14117

211610

292214

372819

506080

100

0000

1100

1111

1111

2111

4332

6554

9876

121198

16141210

125150175200250

00000

00000

00000

11100

11111

11111

32211

44333

65544

87665

325375400500

0000

0000

0000

0000

1000

1111

1111

2111

3221

4333

TW 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

9753

151185

2318137

36282111

53413017

94725430

1411088145

20315611664

27721215888

361277207115


2.0 (1.6) 6 10 15 24 35 62 94 135 184 240

RHH*, RHW*,RHW-2*, THW,THHW,

3.5 (2.0)5.5 (2.6)

54

86

1210

1915

2822

5039

7559

10885

148115

193151


8.0 (3.2) 1 4 6 9 13 23 35 51 69 90


14223038

1111

3111

4321

7542

10754

1813107

27201410

39292115

53392920

69513726

506080

100

0000

1110

1111

1111

3321

6543

9765

121097

17141210

22191613

125150175200250

00000

00000

11000

11111

11111

32111

43332

65443

87665

119876



117

Table A38 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100


325375400500

0000

0000

0000

0000

1110

1111

1111

3221

4332

5443

THHN, THWN,THWN-2

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

13963

2216106

3324159

52382414

76563520

134986235

2021479353

29121213477

396289182105

518378238137

14223038

2111

4211

6431

10643

14964

2516118

38241712

55342418

76463324

99614332

506080

100

1000

1111

1111

2111

4321

7654

10976

1512108

20171412

27221815

125150175200250

00000

00000

11100

11111

11111

33211

54332

76554

98765

1211987

325375400500

0000

0000

0000

0000

1110

1111

1111

3221

4333

5443


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

129642

21151164

322417107

5137261511

7454392216

13095683928

1961431035942

2822061488560

38528120111582

502367263151107

2230

11

31

53

75

117

1913

2920

4229

5739

7551

PFA, PFAH, TFE 38 1 1 2 3 5 9 14 20 27 36

PFA, PFAH,TFE, Z

506080

100

1100

1111

1111

3211

4332

8654

11986

1714119

23191513

30242016

Z 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

1511643

25181175

392817117

6143261712

8963392417

157111684330

2361681036545

3402411489365

46332920112789

605429263166117

223038

111

311

532

854

1276

211210

311915

452722

613730

804939


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

97531

1511853

23181375

362821118

5341301712

9472543022

141108814533

2031561166448

2772121588865

36127720711585

2230

11

21

43

64

96

1611

2417

3424

4733

6144


118

Table A38 Continued

COMPACT CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100

XHH, XHHW,XHHW-2

38 1 1 1 3 5 8 13 18 25 32506080100

1000

1111

1111

2211

4332

7654

10976

1513109

21171412

27231915

125150175200250

00000

00000

11100

11111

11111

33211

54433

76554

108765

1311987

325375400500

0000

0000

0000

0000

1110

1111

1111

3221

4333

5443

FIXTURE WIRES

TypeConductor Size


15 20 25 32 40 50FFH-2, RFH-2, RFHH-3 0.75

1.2587

1412

2219

3529

5143

9076

SF-2, SFF-2 0.751.252.0

1197

181512

282319

443629

645343

1139476

SF-1, SFF-1 0.75 19 32 50 78 114 201


0.75 14 24 37 58 84 148


1.25 11 19 30 47 68 120

XF, XFF 2.0 9 15 23 36 53 94

TFN, TFFN 0.751.25

2317

3829

5945

9371

135103

237181


0.751.252.0

221712

362821

564332

886851

1289974

225174130

HF, HFF, ZF, ZFF, ZHF 0.751.252.0

282015

473525

725339

1138361

16512189

290214157

KF-2, KFF-2 0.751.252.03.55.5

412819139

6848332315

10574513523

164116805536

2391681168053

42129720414094

KF-1, KFF-1 0.751.252.03.55.5

4834231510

8257382516

12588593925

196138936140

2852001358958

503353237157103

XF, XFF 3.55.5

54

86

1210

1915

2822

5039



119

Table A39 Maximum Number of Compact Conductors in FlexibleMetal Conduit (Based on Table 9.1.1.1)



15 20 25 32 40 50 65 80 90 100THW, THHW,THW-2

8.014223038

21111

43211

65321

107543

1411864

252015117

3829221611

5543322316

7558433222

9876574229

506080

100

1000

1111

1111

2111

3321

6544

10876

1412108

19161411

25211815

125150175200250

00000

00000

11100

11111

11111

32211

44333

76554

98765

1210987

325375400500

0000

0000

0000

0000

1110

1111

1111

3221

4333

6554

THHN, THWN,THWN-2

8.014223038

3111

4311

7432

11753

161075

2918139

43271914

62382821

85523828

111694937

506080

100

1100

1111

1111

3211

4432

8654

121087

17141210

24201714

31262218

125150175200250

00000

10000

11110

11111

11111

33321

55433

87654

119876

14121098

325375400500

0000

0000

0000

1000

1110

1111

2111

3331

5443

6554

XHHW,XHHW-2

8.014223038

32111

54311

86432

139753

19141075

332418139

5037271914

7153382821

9772523828

12795694937

506080

100

1100

1111

1111

3211

4432

8754

121087

17151210

24201714

31262218

125150175200250

00000

10000

11110

11111

11111

43321

55443

87654

119876

141211108

325375400500

0000

0000

0000

1000

1111

1111

2111

3332

5443

6554



120

Table A40 Maximum Number of Conductors and Fixture Wires in IntermediateMetal Conduit (Based on Table 9.1.1.1)

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100

RH 2.0 (1.6)3.5 (2.0)

65

119

1814

3125

4234

6956

9879

151122

202163

261209

RHH, RHW,RHW-2

2.0 (1.6)3.5 (2.0)

44

86

1311

2218

3025

4941

7058

10889

144120

186154

RH, RHH, RHW,RHW-2

5.5 (2.6)8.0 (3.2)

14

311

531

843

1586

20108

331714

472419

723830

975040

1246552

223038

110

111

311

532

653

1185

15117

231812

312416

413120

506080100

0000

1100

1111

1111

3211

4433

6654

10976

1412109

18151311

125150175200250

00000

00000

10000

11111

11111

11111

33221

54433

66554

87765

325375400500

0000

0000

0000

0000

1110

1111

1111

2111

3332

4443

TW 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

10753

171395

2721158

47362715

64493620

104805933

1471138447

22817513072

30423417497

392301224124


2.0 (1.6) 6 11 18 31 42 69 98 151 202 261


3.5 (2.0)5.5 (2.6)

54

97

1411

2519

3426

5643

7961

12295

163127

209163


8.0 (3.2) 2 4 7 12 16 26 37 57 76 98


14223038

1111

3211

5431

9653

12964

2015117

28211511

43322316

58433122

75564128

506080100

1000

1111

1111

3211

4332

6544

9865

1412108

19161311

24201714

125150175200250

0000

0000

1100

1111

1111

3211

4432

7644

9865

121087



121

Table A40 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100


325375400500

000

000

000

100

110

111

111

321

433

543

THHN, THWN,THWN-2

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

141063

2417116

39291810

68493118

91674224

1491096839

2111549756

32623815086

436318200115

562410258149

14223038

2111

4311

7432

13854

171075

2817129

40251713

62382720

83513627

107664735

506080

100

1100

1111

1111

3321

4432

8654

11976

1714129

23191613

29242017

125150175200250

00000

00000

11110

11111

11111

33221

54433

87654

109876

13121097

325375400500

0000

0000

0000

1110

1111

1111

2111

3332

5443

6554

FEP, FEPB,PFA, PFAH, TFE

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

1310743

23171275

382820118

6648341914

8965462619

145106764331

2051501076144

3172311669567

42330922112790

545398285163116

2230

11

32

54

106

139

2115

3021

4732

6343

8156

PFA, PFAH, TFE 38 1 1 2 4 6 10 14 22 30 39

PFA, PFAH,TFE, Z

506080

100

1100

1111

1111

4321

5433

8765

121087

19151310

25211714

32272218

Z 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

1611743

28201275

463220129

7956342115

10776462920

175124764833

2471751076847

38127116610573

51036222114098

657466285180127

223038

111

311

633

1065

1487

231411

332016

503025

674133

875343


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

107531

1713954

27211586

4736271511

6449362015

10480593324

147113844735

2281751307253

3042341749771

39230122412492

2230

11

31

43

85

117

1812

2518

3927

5237

6747


122

Table A40 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100

XHH, XHHW,XHHW-2

38 1 1 2 4 5 9 13 20 27 35

506080

100

1100

1111

1111

3321

5432

8654

11976

17141210

23191613

30252017

125150175200250

00000

00000

11110

11111

11111

33321

54433

87654

119876

14121098

325375400500

0000

0000

0000

1110

1111

1111

2111

3332

5443

6554

FIXTURE WIRES

TypeConductor Size


15 20 25 32 40 50FHH-2, RFH-2, RFHH-3 0.75

1.2598

1613

2622

4538

6151

10084

SF-2, SFF-2 0.751.252.0

12108

201713

332722

574738

776451

12610484

SF-1, SFF-1 0.75 21 36 59 101 137 223RFH-1, RFHH-2, TF,TFF, XF, XFF

0.75 15 26 43 75 101 165

RFH-2, TF, TFF, XF, XFF 1.25 12 21 35 60 81 133

XF, XFF 2.0 10 17 27 47 64 104

TFN, TFFN 0.751.25

2519

4232

6953

11991

161123

264201


0.751.252.0

231813

403123

665138

1138766

15311889

250193145

ZF, ZFF, ZHF, HF, HFF 0.751.252.0

302216

523828

856346

14610879

197145107

322238175

KF-2, KFF-2 0.751.252.03.55.5

4431211410

7553362517

12387604127

2121491037047

2872021399564

468330227156104

KF-1, KFF-1 0.751.252.03.55.5

5237251610

9063422818

147103694630

2531781197952

34224016110770

558392264175114

XF, XFF 3.55.5

54

97

1411

2519

3426

5643



123

Table A41 Maximum Number of Compact Conductors inIntermediate Metal Conduit (Based on Table 9.1.1.1)



15 20 25 32 40 50 65 80 90 100THW, THW-2,THHW

8.014223038

21111

43211

76431

1310754

17131075

282216128

4031231712

6248362618

8364483525

10782624532

506080100

1000

1111

1111

3321

4432

7654

10976

1613119

21181513

27232016

125150175200250

00000

00000

11110

11111

11111

33221

54433

76654

109876

13111098

325375400500

0000

0000

0000

1110

1111

1111

2111

3332

5443

6554

THHN, THWN,THWN-2

8.014223038

3111

5311

8533

14965

191286

32201410

45282015

70433123

93584131

120745340

506080100

1100

1111

2111

4332

5443

9765

131097

20161411

26221815

34282419

125150175200250

00000

10000

11111

11111

21111

43322

65443

97765

1210987

151311109

325375400500

0000

0000

0000

1110

1111

1111

2111

4332

5443

7664

XHHW, XHHW-2 8.014223038

32111

64311

97533

1612965

22161286

3727201410

5238282015

8059433123

10780584131

138103745340

506080100

1100

1111

2111

4332

5443

9765

131197

20171411

26221815

34292420

125150175200250

00000

10000

11111

11111

21111

43332

65443

98765

1210987

161312119

325375400500

0000

0000

0000

1110

1111

1111

2111

4332

5443

7664

Definition: Compact stranding is the result of a manufacturing process where thestandard conductor is compressed to the extent that interstices (voids between strandwires) are virtually eliminated.


124

Table A42 Maximum Number of Conductors and Fixture Wires inLiquidtight Flexible Nonmetallic Conduit (Type FNMC-B*) (Based onTable 9.1.1.1)

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

10 15 20 25 32 40 50

RH 2.0 (1.6)3.5 (2.0)

33

65

108

1613

2923

3830

6250

RHH, RHW,RHW-2

2.0 (1.6)3.5 (2.0)

21

43

76

1210

2117

2722

4436

RH, RHH, RHW,RHW-2

5.5 (2.6)8.0 (3.2)

14

111

311

521

843

1476

1897

291512

223038

000

110

111

211

431

643

975

506080100

0000

0000

1100

1111

1111

2111

4332

125150175200250

00000

00000

00000

00000

11111

11111

11111

325375400500

0000

0000

0000

0000

0000

1000

1111

TW 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

5431

9753

151295

2519148

44332514

57433218

93715329

RHH†, RHW†,RHW-2†, THW,THHW, THW-2

2.0 (1.6) 3 6 10 16 29 38 62

RHH†, RHW†,RHW-2†, THHW,THW

3.5 (2.0)5.5 (2.6)

31

53

86

1310

2318

3023

5039


8.0 (3.2) 1 1 4 6 11 14 23

RHH†, RHW†,RHW-2†, TW,THW, THHW,THW-2

14223038

1100

1111

3111

5321

8643

11864

181397

506080100

0000

0000

1110

1111

2211

3321

6543

125150175200250

00000

00000

00000

11000

11111

11111

32111

325375400500

0000

0000

0000

0000

1000

1110

1111

*Corresponds to Section 3.51.2.1(2).†Types RHH, RHW, and RHW-2 without outer covering.


125

Table A42 Continued

CONDUCTORS


(mm dia.)]Raceway Size (mm)

10 15 20 25 32 40 50THHN, THWN,THWN-2

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

85311

139632

22161064

36261697

6346291612

8159372115

13397613525

223038

110

111

211

431

754

975

15118

506080100

0000

1000

1111

1111

3211

4332

7654

125150175200250

00000

00000

00000

11100

11111

11111

33211

325375400500

0000

0000

0000

0000

1000

1110

1111


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

75411

129632

21151164

352518107

6144321813

7957412317

12994683927

2230

11

11

31

53

96

128

1913

PFA, PFAH, TFE 38 0 1 1 2 4 5 9

PFA, PFAH, TFE,Z

506080100

0000

1100

1111

1111

3321

4432

7654

Z 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

96421

1510643

26181175

423018118

7352322014

9567412618

156111684330

223038

100

111

311

532

965

1276

201210


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

54311

97531

1512953

25191486

4433251410

5743321813

9371532922

2230

11

11

21

43

75

97

1611


126

Table A42 Continued

CONDUCTORS


(mm dia.)]Raceway Size (mm)

10 15 20 25 32 40 50XHH, XHHW,XHHW-2

38 0 1 1 1 4 5 8

506080

100

0000

1000

1111

1111

3211

4332

7654

125150175200250

00000

00000

00000

11100

11111

11111

33211

325375400500

0000

0000

0000

0000

1000

1110

1111

FIXTURE WIRES


Raceway Size (mm)

10 15 20 25 32 40 50FFH-2, RFH-2 0.75

1.2554

87

1512

2420

4235

5446

8975

SF-2, SFF-2 0.751.252.0

654

1197

191512

302520

534435

695746

1139375

SF-1, SFF-1 0.75 11 19 33 53 94 122 199RFH-1, RFHH-2, TF,TFF, XF, XFF

0.75 8 14 24 39 69 90 147


1.25 7 11 20 32 56 72 119

XF, XFF 2.0 5 9 15 25 44 57 93

TFN, TFFN 0.751.25

1410

2317

3930

6348

11185

144110

236180


0.751.252.0

13107

211612

372921

604635

1058161

13610579

223173129

HF, HFF, ZF, ZFF, ZHF 0.751.252.0

17129

282015

483526

775742

13610073

17612995

288212156

KF-2, KFF-2 0.751.252.03.55.5

24171285

402819139

7049342315

11279543725

197139956544

2551801238557

41829520213993

KF-1, KFF-1 0.751.252.03.55.5

29201496

4834231510

8358392617

13494634227

2351651117348

3042141449562

499350236156102

XF, XFF 3.55.5

31

53

86

1310

2318

3023

5039

Note: This table is for concentric stranded conductors only. For compactstranded conductors, Table A43 should be used.


127

Table A43 Maximum Number of Compact Conductors in Liquidtight FlexibleNonmetallic Conduit (Type FNMC-B*) (Based on Table 9.1.1.1)

COMPACT CONDUCTORS


Raceway Size (mm)10 15 20 25 32 40 50

THW, THW-2,THHW

8.014223038

11110

21111

43211

75431

129753

1512964

251914117

506080

100

0000

1000

1111

1111

3211

4332

6544

125150175200250

00000

00000

00000

11100

11111

11111

32211

325375400500

0000

0000

0000

0000

1000

1111

1111

THHN, THWN,THWN-2

8.014

—1

2

4

7

13

17

28

223038

110

111

311

432

864

1176

17129

506080

100

0000

1100

1111

1111

4321

5433

8654

125150175200250

00000

00000

10000

11110

11111

11111

33221

325375400500

0000

0000

0000

0000

1110

1111

1111

XHHW,XHHW-2

8.014

11

32

54

96

1511

2015

3324

223038

110

111

311

432

864

1176

17129

506080

100

0000

1100

1111

1111

4321

5433

8754

125150175200250

00000

00000

10000

11110

11111

11111

33321

325375400500

0000

0000

0000

0000

1110

1111

1111

*Corresponds to Section 3.51.2.1(2).Definition: Compact stranding is the result of a manufacturing process where the standard conductors

compressed to the extent that the interstices (voids between strand wires) are virtually eliminated.


128

Table A44 Maximum Number of Conductors and Fixture Wires in LiquidtightFlexible Nonmetallic Conduit (Type FNMC-A*) (Based On Table 9.1.1.1)

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

10 15 20 25 32 40 50

RH 2.0 (1.6)3.5 (2.0)

33

64

108

1613

2823

3831

6451

RHH, RHW,RHW-2

2.0 (1.6)3.5 (2.0)

21

43

76

119

2017

2723

4538

RH, RHH, RHW,RHW-2

5.5 (2.6)8.0 (3.2)

14

111

311

521

843

1375

1897

301613

223038

000

110

111

211

431

643

1075

506080100

0000

0000

1100

1111

1111

2111

4433

125150175200250

00000

00000

00000

00000

11110

11111

11111

325375400500

0000

0000

0000

0000

0000

1000

1111

TW 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

5431

9753

151295

2419148

43332413

58443318

96745530


2.0 (1.6) 3 6 10 16 28 38 64

RHH†, RHW†,RHW-2†, THHW,THW

3.5 (2.0)5.5 (2.6)

31

43

86

1310

2318

3124

5140


8.0 (3.2) 1 1 4 6 10 14 24

RHH†, RHW†,RHW-2†, TW,THW, THHW,THW-2

14223038

1100

1111

3111

4321

8643

11864

1813107

506080100

0000

0000

1110

1111

2111

3321

6543

125150175200250

00000

00000

00000

11000

11111

11111

32111

325375400500

0000

0000

0000

0000

1000

1110

1111

*Correspond to Section 3.51.2.1(1).†Types RHH, RHW,and RHW-2 without outer covering.


129

Table A44 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

10 15 20 25 32 40 50

THHN, THWN,THWN-2

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

85311

139632

22161064

35251696

6245281612

8360382216

137100633626

223038

110

111

211

431

754

975

16118

506080

100

0000

1000

1111

1111

3211

4332

7654

125150175200250

00000

00000

00000

11100

11111

11111

33211

325375400500

0000

0000

0000

0000

1000

1110

1111


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

75411

129632

21151164

342518107

6044311813

8059422417

13397704028

2230

11

11

31

53

96

128

2013

PFA, PFAH,TFE

38 0 1 1 2 4 5 9

PFA, PFAH,TFE, Z

506080

100

0000

1100

1111

1111

3321

5432

8654

Z 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

96421

1510643

25181175

412918118

7251312014

9769422618

161114704431

223038

111

111

311

532

964

1386

211310


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

54311

97531

1512953

24191485

4333241310

5844331813

9674553022

2230

11

11

21

43

75

107

1611


130

Table A44 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

10 15 20 25 32 40 50

XHH, XHHW,XHHW-2

38 0 1 1 1 4 5 8506080

100

0000

1000

1111

1111

3211

4332

7654

125150175200250

00000

00000

00000

11100

11111

11111

33211

325375400500

0000

0000

0000

0000

1000

1110

1111

FIXTURE WIRES

TypeConductor Size


10 15 20 25 32 40 50FFH-2, RFH-2, RFHH-3 0.75

1.2554

87

1412

2320

4135

5547

9277

SF-2, SFF-2 0.751.252.0

654

1197

181512

292420

524335

705847

1169677

SF-1, SFF-1 0.75 12 19 33 52 92 124 205RFH-1, RFHH-2, TF,TFF, XF, XFF

0.75 8 14 24 39 68 91 152


1.25 7 11 19 31 55 74 122

XF, XFF 2.0 5 9 15 24 43 58 96

TFN, TFFN 0.751.25

1410

2217

3929

6247

10983

146112

243185


0.751.252.0

13107

211612

372821

594534

1038060

13910780

230178133

HF, HFF, ZF, ZFF, ZHF 0.751.252.0

17129

272015

473525

765641

1339872

17913297

297219161

KF-2, KFF-2 0.751.252.03.55.5

25171285

402819139

6948332315

11077533624

193136946443

2601831268658

43130320914396

KF-1, KFF-1 0.751.252.03.55.5

29211496

4833221510

8257392517

13192624127

2311621097247

3102181469763

514361243161105

XF, XFF 3.55.5

31

43

86

1310

2318

3124

5140



131

Table A45 Maximum Number of Compact Conductors inLiquidtight Flexible Nonmetallic Conduit (Type FNMC-A*) (Basedon Table 9.1.1.1)

COMPACT CONDUCTORS


Raceway Size (mm)

10 15 20 25 32 40 50THW,THW-2, THHW

8.014223038

11110

21111

43211

65431

119753

1612964

262015118

506080

100

0000

1000

1111

1111

3211

4332

7554

125150175200250

00000

00000

00000

11100

11111

11111

33211

325375400500

0000

0000

0000

0000

1000

1111

1111

THHN, THWN,THWN-2

8.014223038

—1110

2111

4311

7432

13864

181186

29181310

506080

100

0000

1100

1111

1111

3321

5433

8765

125150175200250

00000

00000

10000

11110

11111

11111

33321

325375400500

0000

0000

0000

0000

1110

1111

1111

XHHW,XHHW-2

8.014223038

11110

32111

54311

86432

1511864

20151186

3425181310

506080

100

0000

1100

1111

1111

3321

5433

8765

125150175200250

00000

00000

10000

11110

11111

21111

43321

325375400500

0000

0000

0000

0000

1110

1111

1111

*Corresponds to Section 3.51.2.1(1).


132

Table A46 Maximum Number of Conductors and Fixture Wires in LiquidtightFlexible Metal Conduit (Based on Table 9.1.1.1)

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100

RH 2.0 (1.6)3.5 (2.0)

65

108

1613

2923

3830

6250

9375

143115

186149

243195

RHH, RHW,RHW-2

2.0 (1.6)3.5 (2.0)

43

76

1210

2117

2722

4436

6655

10284

133110

173144

RH, RHH, RHW,RHW-2

5.5 (2.6)8.0 (3.2)

14

311

521

843

1476

1897

291512

442318

683628

894637

1166148

223038

110

111

211

431

643

975

14117

221711

292214

382919

506080

100

0000

1100

1111

1111

2111

4332

6544

10876

131198

16141210

125150175200250

00000

00000

00000

11111

11111

11111

32211

44333

65544

87665

325375400500

0000

0000

0000

0000

1000

1111

1111

2111

3221

4333

TW 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

9753

151295

2519148

44332514

57433218

93715329

1401088044

21516512368

28021516089

365280209116


2.0 (1.6) 6 10 16 29 38 62 93 143 186 243


3.5 (2.0)5.5 (2.6)

53

86

1310

2318

3023

5039

7558

11589

149117

195152


8.0 (3.2) 1 4 6 11 14 23 35 53 70 91


14223038

1111

3111

5321

8643

11864

181397

27201410

41302215

53402920

70523826

506080

100

0000

1110

1111

2211

3321

6543

8765

131198

17151210

23191613

125150175200250

00000

00000

11000

11111

11111

32111

43332

65543

87665

119876



133

Table A46 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100


325375400500

0000

0000

0000

1000

1110

1111

1111

3221

4332

5443

THHN, THWN,THWN-2

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

13963

2216106

3626169

63462916

81593721

133976135

2011469253

30822514181

401292184106

523381240138

14 2 4 7 12 15 25 38 59 76 100223038

111

211

431

754

975

15118

231712

362619

473325

614432

506080

100

1000

1111

1111

3211

4332

7654

10876

1613119

21171412

27231915

125150175200250

00000

00000

11100

11111

11111

33211

54332

76554

108765

1211987

325375400500

0000

0000

0000

1000

1110

1111

1111

3331

4333

6553


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

129632

21151164

352518107

6144321813

7957412317

12994683927

1951421025841

2992181568964

38928420311783

507370266152108

2230

11

31

53

96

128

1913

2920

4430

5840

7552

PFA, PFAH,TFE

38 1 1 2 4 5 9 14 21 28 36

PFA, PFAH,TFE, Z

506080

100

1100

1111

1111

3321

4432

7654

11986

18141210

23191613

30252017

Z 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

2014854

26181175

423018118

7352322014

9567412618

156111684330

2351671026445

3602551569969

46933220312990

611434266168118

223038

211

311

532

965

1276

201210

311915

482923

623830

814940


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

97531

1512953

25191486

4433251410

5743321813

9371532922

140108804433

2151651236850

2802151608966

36528020911686

2230

11

21

43

75

97

1611

2417

3626

4834

6244



134

Table A46 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100

XHH, XHHW,XHHW-2

38 1 1 1 4 5 8 12 19 25 33506080

100

1000

1111

1111

3211

4332

7654

10976

1613119

21171412

28231916

125150175200250

00000

00000

11100

11111

11111

33211

54332

76554

108765

13111087

325375400500

0000

0000

0000

1000

1110

1111

1111

3331

4333

6553

FIXTURE WIRES

TypeConductor Size


15 20 25 32 40 50FFH-2, RFH-2, RFHH-3 0.75

1.2587

1512

2420

4235

5446

8975

SF-2, SFF-2 0.751.252.0

1197

191512

302520

534435

695746

1139375


0.75 14 24 39 69 90 147


1.25 11 20 32 56 72 119

XF, XFF 2.0 9 15 25 44 57 93

TFN, TFFN 0.751.25

2317

3930

6348

11185

144110

236180


0.751.252.0

211612

372921

604635

1058161

13610579

223173129

HF, HFF, ZF, ZFF, ZHF 0.751.252.0

282015

483526

775742

13610073

17612995

288212156

KF-2, KFF-2 0.751.252.03.55.5

402819139

7049342315

11279543725

197139956544

2551801238557

41829520213993

KF-1, KFF-1 0.751.252.03.55.5

4834231510

8358392617

13494634227

2351651117348

3042141449562

499350236156102

XF, XFF 3.55.5

53

86

1310

2318

3023

5039



135

Table A47 Maximum Number of Compact Conductors inLiquidtight Flexible Metal Conduit (Based on Table 9.1.1.1)

COMPACT CONDUCTORS


Raceway Size (mm)10 15 20 25 32 40 50 65 80 90 100

THW, THW-2,THHW

8.014

11

21

43

75

129

1512

2519

3829

5845

7659

9977

223038

110

111

211

431

753

964

14117

221611

342517

443223

574230

506080

100

0000

1000

1111

1111

3211

4332

6544

10876

1513119

20161412

26211815

125150175200250

00000

00000

00000

11100

11111

11111

32211

44333

76554

98765

1210987

325375400500

0000

0000

0000

0000

1000

1111

1111

1111

3331

4333

6554

THHN, THWN,THWN-2

8.014

1

2

4

7

13

17

28

43

66

86

112

223038

110

111

311

432

864

1176

17129

261914

412922

533828

695037

506080

100

0000

1100

1111

1111

4321

5433

8654

121087

19151310

24201714

32262218

125150175200250

00000

00000

10000

11110

11111

11111

33221

54433

87655

119876

14121198

325375400500

0000

0000

0000

0000

1110

1111

1111

2111

4332

5443

6554

XHHW,XHHW-2

8.014

11

32

54

96

1511

2015

3324

4937

7656

9873

12995

223038

110

111

311

432

864

1176

17129

261914

412922

533828

695037

506080

100

0000

1100

1111

1111

4321

5433

8754

121087

19161311

24201714

32272218

125150175200250

00000

00000

10000

11110

11111

11111

33321

55443

87665

119876

151211108

325375400500

0000

0000

0000

0000

1110

1111

1111

2111

4332

5443

6554

Definition: Compact stranding is the result of a manufacturing process where the standard conductorscompressed to the extent that the interstices (voids between strand wires) are virtually eliminated.


136

Table A48 Maximum Number of Conductors and Fixture Wires in Rigid Metal Conduit(Based on Table 9.1.1.1)

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100 125 150

RH 2.0 (1.6)3.5 (2.0)

65

108

1713

2923

3932

6552

9375

143115

191154

246198

387311

558448

RHH, RHW,RHW-2

2.0 (1.6)3.5 (2.0)

43

76

1210

2117

2823

4638

6655

10285

136113

176146

276229

398330

RH, RHH, RHW,RHW-2

5.5 (2.6)8.0 (3.2)

14

311

521

843

1476

19108

311613

442318

683629

914838

1186149

1859777

267139112

223038

110

111

211

431

643

1075

14117

221711

302315

382919

604630

876644

506080

100

0000

1100

1111

1111

2211

4433

6544

10876

1311108

17141211

26232017

38332824

125150175200250

00000

00000

00000

11111

11111

11111

32211

44433

65544

87665

13111098

1816151311

325375400500

0000

0000

0000

0000

1000

1111

1111

2111

3331

4333

6554

9886

TW 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

9753

151295

2519148

44332514

59453419

98755631

1401078044

21616512368

28822116491

370284212118

581446332185

839644480267


2.0 (1.6) 6 10 17 29 39 65 93 143 191 246 387 558


3.5 (2.0)5.5 (2.6)

53

86

1310

2318

3225

5241

7558

11590

154120

198154

311242

448350


8.0 (3.2) 1 4 6 11 15 24 35 54 72 92 145 209


14223038

1111

3111

5321

8643

11864

1814107

27201410

41312215

55413021

71533827

111836042

1601208761

506080

100

0000

1110

1111

2211

3321

6543

8765

131198

18151310

23191614

36312621

52443731

125150175200250

00000

00000

11000

11111

11111

32111

43332

65543

87665

119876

1715131210

2522191714



137

Table A48 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100 125 150


325375400500

0000

0000

0000

1000

1110

1111

1111

3221

4332

5443

8775

1210108

THHN, THWN,THWN-2

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

13963

2216106

3626179

63462916

85623922

1401026437

2001469253

30922514282

412301189109

531387244140

833608383221

1202877552318

14 2 4 7 12 16 27 38 59 79 101 159 230223038

111

211

431

754

1075

16118

231712

362619

483425

624433

987051

14110074

506080

100

1000

1111

1111

3211

4332

7654

10876

1613119

21181512

27231916

43363025

63524336

125150175200250

00000

00000

11110

11111

11111

33221

54332

76554

108775

13111087

2017151311

2925222016

325375400500

0000

0000

0000

1000

1111

1111

1111

3331

4443

6554

9776

1311118


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

129632

22161164

352618107

6144321813

8360432517

13699714129

1941421025841

3002191579064

40029220912085

515376269154110

808590423242172

1166851610350249

2230

11

31

53

96

128

2014

2920

4431

5941

7753

12083

174120

PFA, PFAH, TFE 38 1 1 2 4 6 9 14 21 28 37 57 83

PFA, PFAH, TFE,Z

506080

100

1100

1111

1111

3321

5432

8654

11986

18141210

24191613

30252117

48403327

69574739

Z 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

1510643

26181175

423018118

7352322014

10071432719

164116714531

2341661026445

3612561579969

48234220913293

621440269170120

974691423267188

1405997610386271

223038

111

311

532

965

1386

221310

311915

482923

643931

825040

1297863

18611392


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

97531

1512953

25191486

4433251410

5945341914

9875563123

140107804433

2161651236851

2882211649168

37028421211887

581446332185137

839644480267197

2230

11

21

43

75

107

1612

2417

3726

4935

6345

9970

143101


138

Table A48 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100 125 150

XHH, XHHW,XHHW-2

38 1 1 1 4 5 9 12 19 26 33 52 76506080100

1000

1111

1111

3211

4332

7654

10976

1613119

22181512

28231916

44373025

64534436

125150175200250

00000

00000

11110

11111

11111

33221

54332

76654

109775

13111097

2018151411

3025222016

325375400500

0000

0000

0000

1000

1111

1111

1111

3331

4443

6554

9776

1311118

FIXTURE WIRES

TypeConductor Size


15 20 25 32 40 50FFH-2, RFH-2, RFHH-3 0.75

1.2587

1512

2420

4235

5748

9479

SF-2, SFF-2 0.751.252.0

1197

191512

312520

534435

725948

1189879

SF-1, SFF-1 0.75 19 33 54 94 127 209


0.75 14 25 40 69 94 155


1.25 11 20 32 56 76 125

XF, XFF 2.0 9 15 25 44 59 98TFN, TFFN 0.75

1.252317

4030

6449

11184

150115

248189


0.751.252.0

211612

382922

614735

1058161

14311083

235181136

HF, HFF, ZF, ZFF, ZHF 0.751.252.0

282015

483626

795842

13510073

184136100

303223164

KF-2, KFF-2 0.751.252.03.55.5

402819139

7150342315

11480553825

197138956544

2671881298959

43931021314698

KF-1, KFF-1 0.751.252.03.55.5

4834231510

8459402617

13696644228

2351651117348

31822415010065

524368248164107

XF, XFF 3.55.5

53

86

1310

2318

3225

5241



139

Table A49 Maximum Number of Compact Conductors in RigidMetal Conduit (Based on Table 9.1.1.1)

COMPACT CONDUCTORS


Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100 125 150THW,THW-2, THHW

8.014

21

43

75

129

1612

2620

3829

5945

7860

10178

158122

228176

223038

111

211

431

753

975

15118

221611

342517

453323

584330

916747

1329768

506080100

1000

1111

1111

3211

4332

7654

10876

1513119

20171412

26221915

41342924

59504235

125150175200250

00000

00000

11110

11111

11111

33211

44333

76554

98775

1211987

1917151311

2824222017

325375400500

0000

0000

0000

1000

1111

1111

1111

3331

4443

6554

9776

1311119

THHN, THWN,THWN-2

8.014

2

5

8

13

18

30

43

66

88

114

179

258

223038

111

311

532

864

1186

181310

261914

412922

553929

705038

1107960

15911486

506080100

1100

1111

1111

4321

5433

8765

121087

19151310

25211714

32262218

51423529

73605142

125150175200250

00000

10000

11110

11111

21111

43321

54433

87655

1110876

141211108

2320171513

3328252219

325375400500

0000

0000

0000

1110

1111

1111

2111

4332

5443

6554

10996

1513139

XHHW,XHHW-2

8.014

32

54

96

1511

2115

3425

4936

7656

10175

13097

205152

296220

223038

111

311

532

864

1186

181310

261914

412922

553929

705038

1107960

15911486

506080100

1100

1111

1111

4321

5433

8765

121087

19161311

25211714

32272219

51433529

73625142

125150175200250

00000

10000

11110

11111

21111

43321

55443

87665

1110986

151311108

2320181613

3429252319

325375400500

0000

0000

0000

1110

1111

1111

2111

4332

5443

7554

10887

15121210

Definition: Compact stranding is the result of a manufacturing process where the standard conductorscompressed to the extent that the interstices (voids between strand wires) are virtually eliminated.


140

Table A50 Maximum Number of Conductors and Fixture Wires inRigid PVC Conduit, Schedule 80 (Based on Table 9.1.1.1)

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100 125 150

RH 2.0 (1.6)3.5 (2.0)

43

86

1310

2319

3226

5544

7963

12399

166133

215173

341274

490394

RHH, RHW, RHW-2

2.0 (1.6)3.5 (2.0)

32

54

97

1714

2319

3932

5646

8873

11898

153127

243202

349290

RH, RHH, RHW,RHW-2

5.5 (2.6)8.0 (3.2)

14

111

311

632

1164

1586

261311

371916

593124

794133

1035443

1638568

23412298

223038

100

111

111

331

542

864

1296

19149

262013

332517

534127

775838

506080100

0000

0000

1110

1111

1111

3332

5443

8765

111087

1513119

23201715

33292521

125150175200250

00000

00000

00000

11100

11111

11111

22111

43332

55443

76554

1110987

1614131210

325375400500

0000

0000

0000

0000

0000

1111

1111

1111

3221

3332

6554

8775

TW 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

6531

11963

2015116

35272011

49382815

82634726

118916737

18514210659

25019214379

324248185103

514394294163

736565421234


2.0 (1.6) 4 8 13 23 32 55 79 123 166 215 341 490


3.5 (2.0)5.5 (2.6)

32

65

108

1915

2620

4434

6349

9977

133104

173135

274214

394307


8.0 (3.2) 1 3 5 9 12 20 29 46 62 81 128 184

RHH*, RHW*,RHW-2*, TW,THW THHW,THW-2

14223038

1110

1111

3311

7532

9753

161286

2217128

35261913

48352618

62463323

98735337

1411057754

506080100

0000

1100

1111

1111

3211

5433

7654

111087

1513119

20171412

32272319

46393327

125150175200250

00000

00000

00000

11111

11111

21111

33221

55443

76654

98775

151312109

2219171513

325375400500

0000

0000

0000

0000

1000

1111

1111

2111

3332

4443

7665

10887



141

Table A50 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100 125 150

THHN, THWN,THWN-2

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

9642

171274

2820137

51372313

70513218

118865431

1701247845

26519312270

35826116495

464338213123

736537338195

1055770485279

14 1 3 5 9 13 22 32 51 68 89 141 202223038

110

111

321

643

864

14107

201410

312216

423022

543929

866145

1248865

506080100

0000

1110

1111

2111

3321

6543

9765

141198

18151310

24201714

38322622

55463831

125150175200250

00000

00000

10000

11111

11111

32111

43332

65543

87665

119876

1815131210

2522191714

325375400500

0000

0000

0000

0000

1110

1111

1111

3221

4332

5443

8775

12997


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

86421

1612853

27201486

4936261510

6850362014

11584603424

164120864935

2571881357755

34725318210474

45032823513596

714521374214152

1024747536307218

2230

11

21

43

75

107

1712

2417

3826

5235

6746

10673

153105

PFA, PFAH, TFE 38 1 1 1 3 5 8 11 18 25 32 51 73

PFA, PFAH,TFE, Z

506080100

0000

1110

1111

3211

4321

7544

10865

1512108

20171411

27221815

42352924

61504134

Z 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

107432

1914854

33231496

5942261611

8258362216

13898603826

198141865438

3102201358560

41829718211581

542385235149104

860610374236166

1233875536339238

223038

110

211

422

854

1165

18119

261613

412520

553327

724335

1146956

1649980


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

65311

119632

20151164

352720118

4938281511

8263472619

11891673728

1851421065943

2501921437959

32424818510376

514394294163121

736565421234173

2230

11

11

32

64

86

1410

2014

3122

4230

5539

8762

12589


142

Table A50 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100 125 150

XHH, XHHW,XHHW-2

38 0 1 1 3 4 7 10 16 22 29 46 66506080100

0000

1110

1111

2111

3321

6543

9765

141198

19161311

24201714

39322722

56463832

125150175200250

00000

00000

11000

11111

11111

32111

43332

65543

97665

1110876

1815141210

2622201714

325375400500

0000

0000

0000

0000

1110

1111

1111

3221

4332

5443

8665

11997

FIXTURE WIRES

TypeConductor Size


15 20 25 32 40 50FFH-2, RFH-2, RFHH-3 0.75

1.2565

119

1916

3428

4739

7967

SF-2, SFF-2 0.751.252.0

765

14119

242016

433528

594939

1008267

SF-1, SFF-1 0.75 13 25 42 76 105 177


0.75 10 18 31 56 77 130


1.25 8 15 25 45 62 105

XF, XFF 2.0 6 11 20 35 49 82

TFN, TFFN 0.751.25

1612

2922

5038

9068

12495

209159


0.751.252.0

15118

282216

473627

856649

1189168

198153115

HF, HFF, ZF, ZFF, ZHF 0.751.252.0

191410

362719

614533

1108159

15211282

255188138

KF-2, KFF-2 0.751.252.03.55.5

28191396

5337251711

8862432920

159112775335

2201551077349

37126117912382

KF-1, KFF-1 0.751.252.03.55.5

332316107

6344291913

10674503321

190133905939

2631851248254

44231020913890

XF, XFF 3.55.5

32

65

108

1915

2620

4434



143

Table A51 Maximum Number of Compact Conductors in Rigid PVC Conduit,Schedule 80 (Based on Table 9.1.1.1)

COMPACT CONDUCTORS


Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100 125 150THW, THW-2,THHW

8.014223038

11110

32111

54311

97543

1310754

22171396

322518139

5039292115

6852392920

8868513726

140108816042

2001551168560

506080

100

0000

1100

1111

2111

3321

6543

8765

131198

17151210

23191613

36302622

52443731

125150175200250

00000

00000

10000

11111

11111

22111

43332

65543

87665

119876

1715131210

2521191714

325375400500

0000

0000

0000

0000

1110

1111

1111

3221

4332

5443

8775

1210108

THHN, THWN,THWN-2

8.014223038

1111

3111

6321

11653

15965

2515118

36221612

57352519

77473425

99614433

158987053

22614010075

506080

100

0000

1110

1111

3211

4332

7654

10876

1613119

22181512

28231916

45373125

64534437

125150175200250

00000

00000

11000

11111

11111

33211

44332

76554

108765

1211987

2017151311

2925221916

325375400500

0000

0000

0000

1000

1110

1111

1111

3331

4443

6553

9885

1311118

XHHW, XHHW-2 8.014223038

11111

43111

75321

129653

1713965

292115118

4231221612

6548352519

8865473425

11485614433

181134987053

26019314010075

506080

100

0000

1110

1111

3211

4332

7654

10876

1613119

22181512

28241916

45383126

64544437

125150175200250

00000

00000

11100

11111

11111

33211

54332

76554

108775

13111097

2117151411

3025222017

325375400500

0000

0000

0000

1000

1110

1111

1111

3221

4333

6553

9776

1311118

Definition: Compact stranding is the result of a manufacturing process where thestandard conductors compressed to the extent that the interstices (voids between strandwires) are virtually eliminated.


144

Table A52 Maximum Number of Conductors and Fixture Wires in RigidPVC Conduit, Schedule 40 and HDPE Conduit (Based on Table 9.1.1.1)

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100 125 150

RH 2.0 (1.6)3.5 (2.0)

54

98

1612

2822

3830

6350

9072

139112

186150

240193

378304

546439

RHH, RHW, RHW-2

2.0 (1.6)3.5 (2.0)

43

75

119

2016

2722

4537

6453

9982

133110

171142

269224

390323

RH, RHH, RHW,RHW-2

5.5 (2.6)8.0 (3.2)

14

211

421

743

1375

1897

301512

432218

663528

894637

1156048

1819476

261137109

223038

110

111

211

431

643

1075

14107

221611

292214

372819

594529

856543

506080100

0000

1000

1111

1111

2111

4332

6544

9876

131198

16141210

26221916

37322824

125150175200250

00000

00000

00000

11110

11111

11111

32211

44333

65544

87665

12111098

1816141311

325375400500

0000

0000

0000

0000

1000

1111

1111

2111

3221

4333

6554

9886

TW 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

8642

141184

2418137

42322413

57443218

94725430

1351037743

20916011966

28021516089

361277206115

568436325181

822631470261


2.0 (1.6) 5 9 16 28 38 63 90 139 186 240 378 546


3.5 (2.0)5.5 (2.6)

43

86

1210

2217

3024

5039

7256

11287

150117

193150

304237

439343


8.0 (3.2) 1 3 6 10 14 23 33 52 70 90 142 205

RHH*, RHW*,RHW-2*, TW,THW, THHN,THW-2

14223038

1110

2111

4321

8643

11864

1813107

26191410

40302215

53402920

69513726

109815941

1571178560

506080100

0000

1110

1111

2111

3321

6543

8765

131198

17151210

22191613

35302521

51433630

125150175200250

00000

00000

11000

11111

11111

32111

43332

65543

87665

119876

1715131210

2521191714

325375400500

0000

0000

0000

0000

1110

1111

1111

3221

4332

5443

8665

1110107



145

Table A52 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100 125 150

THHN, THWN,THWN-2

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

11853

211595

3425159

60432716

82593721

135996236

1931418951

29921813779

401293184106

517377238137

815594374216

1178859541312

14 1 4 6 11 15 26 37 57 77 99 156 225223038

111

211

431

753

975

16118

221612

352518

473325

614332

966850

1389873

506080

100

1000

1111

1111

3211

4332

7654

10876

1513119

21171412

37221815

42352924

61514235

125150175200250

00000

00000

11100

11111

11111

33211

44332

76554

108765

1211987

2017151311

2824211916

325375400500

0000

0000

0000

1000

1110

1111

1111

3221

4333

5443

9776

1311118


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

11863

2015106

33241710

58423017

79584124

131966939

1881379856

29021215287

389284204117

502366263150

790577414237

1142834598343

142230

211

431

753

1286

17128

281913

402819

624330

835840

1077551

16911881

244170117

PFA, PFAH, TFE 38 1 1 2 4 5 9 13 20 28 36 56 81

PFA, PFAH, TFE,Z

506080

100

1000

1111

1111

3321

4432

8654

11976

1714129

23191613

30242016

47393226

68564638

Z 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

139632

24171064

402817117

7049301913

9568412618

158112694330

226160986243

3502481529667

46933320412990

605429263166116

952675414261184

1376976598378265

223038

111

311

532

954

1276

211210

301814

462823

623830

804939

1267762

18311190


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

86421

1411843

24181375

4232241310

5744321813

9472543022

135103774332

2091601196649

2802151608966

36127720611585

568436325181134

822631470261193

2230

11

21

43

75

97

1611

2316

3525

4834

6144

9769

14099


146

Table A52 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100 125 150

XHH, XHHW,XHHW-2

38 1 1 1 3 5 8 12 19 25 32 51 74506080

100

1000

1111

1111

3211

4332

7654

10876

1613119

21171412

27231915

43363024

62524335

125150175200250

00000

00000

11100

11111

11111

33211

54332

76554

108765

1311987

2017151311

2925221916

325375400500

0000

0000

0000

1000

1110

1111

1111

3221

4333

5443

9776

1311118

FIXTURE WIRES

TypeConductor Size


15 20 25 32 40 50FFH-2, RFH-2, RFHH-3 0.75

1.2586

1412

2319

4033

5446

9076

SF-2, SFF-2 0.751.252.0

1086

171412

292419

504233

695746

1149476


0.75 13 23 38 66 90 149


1.25 10 18 30 53 73 120

XF, XFF 2.0 8 14 24 42 57 94

TFN, TFFN 0.751.25

2016

3728

6046

10580

144110

239183


0.751.252.0

191511

352720

574433

1007758

13710679

227175131

HF, HFF, ZF, ZFF, ZHF 0.751.252.0

251813

453324

745440

1299570

17613095

292216158

KF-2, KFF-2 0.751.252.03.55.5

362617128

6546312214

10775523524

187132906242

2561801248557

42429920514194

KF-1, KFF-1 0.751.252.03.55.5

433020139

7855372416

12890604026

2231571057045

3052141449562

506355239158103

XF, XFF 3.55.5

43

86

1210

2217

3024

5039



147

Table A53 Maximum Number of Compact Conductors in Rigid PVC Conduit,Schedule 40 and HDPE Conduit (Based on Table 9.1.1.1)

COMPACT CONDUCTORS


Raceway Size (mm)15 20 25 32 40 50 65 80 90 100 125 150

THW, THW-2,THHW

8.014223038

11111

43111

65321

119653

1512964

262015117

3728211511

5744332417

7659443223

9876574229

155119896646

2241731299567

506080100

0000

1111

1111

3211

4332

6554

9875

1512109

20161412

25211815

40342924

58494235

125150175200250

00000

00000

11100

11111

11111

32211

44332

76554

98765

1210987

1916151311

2724211916

325375400500

0000

0000

0000

1000

1111

1111

1111

3221

4333

5554

9776

1311119

THHN, THWN,THWN-2

8.014223038

2111

4211

7432

13854

171186

2918139

41251814

64402821

86533829

111684937

1751087758

25315611284

506080100

1000

1111

1111

3321

5433

8754

12986

18151210

24201714

31262218

49413428

72595041

125150175200250

00000

00000

11110

11111

11111

33321

54433

87654

119876

14121098

2219171513

3228242218

325375400500

0000

0000

0000

1110

1111

1111

2111

4332

5443

6554

10886

1512129

XHHW,XHHW-2

8.014223038

31111

54211

86432

1411854

20151186

332518139

4735251814

7355402821

9973533829

12794684937

2001491087758

29021515611284

506080100

1100

1111

1111

3321

5433

8755

121087

18151210

24201714

31262218

49423429

72605042

125150175200250

00000

00000

11110

11111

11111

43321

54433

87654

119876

141211108

2319171513

3328252218

325375400500

0000

0000

0000

1110

1111

1111

2111

4332

5443

6554

10886

1512129



148

Table A54 Maximum Number of Conductors and Fixture Wires inType A, Rigid PVC Conduit (Based on Table 9.1.1.1)

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100

RH 2.0 (1.6)3.5 (2.0)

76

1210

2016

3427

4435

7056

10484

157126

204164

262211

RHH, RHW,RHW-2

2.0 (1.6)3.5 (2.0)

54

97

1512

2420

3126

4941

7461

11293

146121

187155

RH, RHH, RHW,RHW-2

5.5 (2.6)8.0 (3.2)

14

311

632

1054

1686

21119

331714

502621

753931

985141

1256552

223038

110

111

321

542

753

1185

16128

241812

322416

413120

506080

100

0000

1110

1111

2111

3211

5433

7654

10987

1412109

18151311

125150175200250

00000

00000

11000

11111

11111

11111

33221

54443

76554

87765

325375400500

0000

0000

0000

0000

1110

1111

1111

2111

3332

4443

TW 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0(3.2)

11863

1814106

31241810

51392916

67513821

105806033

1571208950

23518113575

30723617698

395303226125


2.0 (1.6) 7 12 20 34 44 70 104 157 204 262


3.5 (2.0)5.5 (2.6)

64

108

1613

2721

3528

5644

8465

12698

164128

211165


8.0 (3.2) 2 4 8 12 16 26 39 59 77 98


14223038

1111

3211

6431

9753

13975

2015117

30221611

45332417

59443222

75564129

506080

100

1000

1111

1111

3211

4332

6544

10876

1412109

19161311

24211714

125150175200250

00000

00000

11110

11111

11111

32211

44332

76554

98765

1210987



149

Table A54 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100


325375400500

0000

0000

0000

1110

1111

1111

1111

3331

4333

5443

THHN, THWN,THWN-2

2.0 (1.6)3.5 (2.0)5.5 (2.6)

16117

271912

443220

735333

967044

15010969

225164103

338246155

441321202

566412260

8.0 (3.2)14223038

43111

75311

128532

1914864

25181186

402817129

5943261914

8964392821

11784523727

150108664735

506080

100

1100

1111

2111

4321

5433

8654

111086

17141210

23191613

29242017

125150175200250

00000

10000

11111

11111

21111

33221

54433

87654

109876

14121097

325375400500

0000

0000

0000

1110

1111

1111

2111

3332

5443

6554


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

14

1511843

26191385

433122139

7051372115

9368482820

146106764431

2181591146546

3272391719870

42731222412891

549400287165117

2230

11

42

64

107

149

2115

3222

4933

6444

8256

PFA, PFAH, TFE 38 1 1 3 5 6 10 15 23 30 39

PFA, PFAH,TFE, Z

506080

100

1110

1111

2111

4332

5433

8765

131097

19161311

25211714

32272218

Z 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

181385

3122138

52372214

85603723

112794830

1751247648

26318611472

395280171108

515365224141

661469287181

14223038

3211

6421

10743

161175

211597

34231411

50352117

76523226

99684133

127885343


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

11863

1814106

31241810

51392916

67513821

105806033

1571208950

23518113575

30723617698

395303226125

142230

211

431

753

1286

15118

241812

372619

554028

755237

936748



150

Table A54 Continued

CONDUCTORS


(mm dia.)]

Raceway Size (mm)

15 20 25 32 40 50 65 80 90 100

XHH, XHHW,XHHW-2

38 1 1 3 4 6 9 14 21 28 35506080

100

1100

1111

2111

4321

5433

8654

121087

18151210

23191613

30252017

125150175200250

00000

10000

11111

11111

21111

33321

55433

87654

119876

14121098

325375400500

0000

0000

0000

1110

1111

1111

2111

3332

5443

6554

FIXTURE WIRES

TypeConductor Size


15 20 25 32 40 50FFH-2, RFH-2, RFHH-3 0.75

1.25109

1815

3025

4841

6454

10085

SF-2, SFF-2 0.751.252.0

13119

221815

373125

615141

816754

12710585


0.75 17 29 49 80 105 165


1.25 14 24 39 65 85 134

XF, XFF 2.0 11 18 31 51 67 105

TFN, TFFN 0.751.25

2821

4736

7960

12898

169129

265202


0.751.252.0

262015

453526

745843

1229470

16012493

251194146

HF, HFF, ZF, ZFF, ZHF 0.751.252.0

342518

584231

967152

15711685

206152112

324239175

KF-2, KFF-2 0.751.252.03.55.5

4935241611

8459402818

14098674631

2281601107651

30021114510067

470331228157105

KF-1, KFF-1 0.751.252.03.55.5

5941281812

10070473120

167117795234

2721911288555

35725116911273

561394265175115

XF, XFF 3.55.5

64

108

1613

2721

3528

5644



151

Table A55 Maximum Number of Compact Conductors in Type A, RigidPVC Conduit (Based on Table 9.1.1.1, Chapter 9)

COMPACT CONDUCTORS


Raceway Size (mm)15 20 25 32 40 50 65 80 90 100

THW, THW-2,THHW

8.014223038

32111

54311

86532

1410864

18141075

282216128

4233241813

6449372719

8465483625

10783624632

506080100

1100

1111

1111

3321

4433

7654

11986

16141210

21181513

28232017

125150175200250

00000

10000

11111

11111

11111

33221

54433

87654

109876

13111098

325375400500

0000

0000

0000

1110

1111

1111

2111

3332

5443

6554

THHN, THWN,THWN-2

8.014223038

3111

5321

9643

15975

201297

32201410

48302116

72453224

94584231

121755440

506080100

1110

1111

2111

4332

6543

9765

131198

20171411

27221815

34282419

125150175200250

00000

11000

11111

11111

21111

43322

65443

98765

1210987

151311109

325375400500

0000

0000

0000

1110

1111

1111

3221

4332

5443

7664

XHHW,XHHW-2

8.014223038

43111

65321

118643

1813975

23171297

3727201410

5541302116

8362453224

10880584231

139103755440

506080100

1110

1111

2111

4332

6543

9765

131198

20171412

27221815

34292420

125150175200250

00000

11000

11111

11111

21111

43332

65543

98765

1210987

161312119

325375400500

0000

0000

0000

1110

1111

1111

3221

4332

5443

7664



152

Table A56 Maximum Number of Conductors in Type EB, PVC Conduit (Based onTable 9.1.1.1)

CONDUCTORS

TypeConductor Size

[mm2 (mm dia.)]Raceway Size (mm)

50 80 90 100 125 150RH 2.0 (1.6)

3.5 (2.0)7459

166134

217175

276222

424341

603485

RHH, RHW,RHW-2

2.0 (1.6)3.5 (2.0)

5344

11998

155128

197163

303251

430357

RH, RHH, RHW,RHW-2

5.5 (2.6)8.0 (3.2)

14

351815

794133

1045443

1326955

20310685

288151121

223038

1196

262013

342617

433321

665033

947247

506080

100

5443

111087

1513119

19161412

29252218

41363126

125150175200250

21111

55443

76554

98765

141211109

2017161412

325375400500

1111

3211

3322

4433

7655

10977

TW 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

111856335

25019214379

327251187104

415319238132

638490365203

907696519288


2.0 (1.6) 74 166 217 276 424 603

RHH*, RHW*,RHW-2*,THHW, THW

3.5 (2.0)5.5 (2.6)

5946

134104

175136

222173

341266

485378


8.0 (3.2) 28 62 81 104 159 227


14223038

2116118

48362618

62463424

79594330

122916646

1731299466

506080

100

7654

1513119

20171412

26221815

40342824

56484034

125150175200250

33221

76654

108775

1211987

1917151311

2724211916

325375400500

1111

3322

4433

6544

9766

131188



153

Table A56 Continued

CONDUCTORS


Raceway Size (mm)50 80 90 100 125 150

THHN, THWN,THWN-2

2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

1591167342

35926216595

468342215124

595434274158

915667420242

1300948597344

14223038

30191310

68423022

89553929

114705037

1751077657

24815310980

506080

100

8754

18151310

24201714

31262118

48403327

68564739

125150175200250

43321

87665

1110876

141211108

2219171512

3127242118

325375400500

1111

4322

5433

6544

10866

141299


2.0 (1.6)3.5 (2.0)5.5 (2.6)

15511381

348254182

454332238

578422302

888648465

1261920660

8.0 (3.2)142230

46332316

104745236

136976846

1731238659

26618913291

378269188129

PFA, PFAH, TFE 38 11 25 32 41 63 90

PFA, PFAH,TFE, Z

506080

100

9765

20171411

27221815

34282319

53433629

75625142

Z 2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

1861328151

419297182115

547388238150

696494302191

1069759465294

15191078660417

14223038

36241512

81553427

105724436

134925645

2061428670

29320112299


2.0 (1.6)3.5 (2.0)5.5 (2.6)8.0 (3.2)

111856335

25019214379

327251187104

415319238132

638490365203

907696519288

142230

261913

594230

775639

987150

15010977

213155110



154

Table A56 Continued

CONDUCTORS


Raceway Size (mm)50 80 90 100 125 150

XHH, XHHW,XHHW-2

38 10 22 29 37 58 82506080

100

8765

19161311

25201714

31262218

48403327

69574739

125150175200250

43321

97665

1110986

151211108

2219171512

3228242218

325375400500

1111

4322

5433

6544

10866

141299



155

Table A57 Maximum Number of Compact Conductors in Type EB,PVC Conduit (Based on Table 9.1.1.1)

CONDUCTORS

TypeConductor Size


50 80 90 100 125 150THW, THW-2, THHW

8.014223038

302317139

6852392920

8969513826

11387654834

1741341007452

24719114310574

506080100

8654

17151210

23191614

29242117

45383227

64544638

125150175200250

33321

87665

119876

141211108

2119171512

3026242118

325375400500

1111

4322

5433

6544

10877

141299

THHN, THWN,THWN-2

8.014223038

34211511

77473425

100624433

128795742

1961218765

27917212493

506080100

9865

22181512

28232016

36302520

56463832

79655545

125150175200250

44332

108765

1311987

161412119

2522191714

3531272420

325375400500

1111

4433

6533

7644

11977

16141010

XHHW,XHHW-2

8.014223038

3929211511

8865473425

11585624433

146109795742

2251671218765

32023817212493

506080100

9865

22181512

28242016

36302521

56473832

79675546

125150175200250

44332

108775

13111097

171412119

2622191714

3731282520

325375400500

1111

4333

6544

7655

11977

16131010



156


157

ANNEX B

Conductor Application and Insulation


158

Table B1. Conductor Application and InsulationsTrade Name Type

LetterMaximumOperating

Temperature

ApplicationProvisions

InsulationOuter

CoveringaMaterial Conductor

Area (mm2)Thickness

(mm)

Fluorinatedethylenepropylene

FEPor

FEPB

90°C

200°C

Dry and damp locations

Dry locations — specialapplicationsb

Flourinatedethylene

Propylene

2.0 – 5.5

8.0 – 30

0.50

0.80

None

Flourinatedethylene

Propylene

2.0 – 8.0 0.40 Glass braid

14 – 30 0.40 Other suitablebraid material

Mineral insulation(metalsheathed)

MI 90°C

250°C

Dry and wet locations

For special applicationsb

Magnesium oxide 0.75 – 1.25c

1.25 – 5.55.6 – 2223 – 250

0.580.901.301.40

Copper oralloy steel

Moisture-, heat-,andoil-resistantthermoplastic

MTW 60°C

90°C

Machine tool wiring in wetlocations as permitted inNFPA 79 see Article 6.70)

Machine tool wiring in drylocations as permitted inNFPA 79 (see Article 6.70)

Flame-retardantmoisture-, heat-,andoil-resistantthermoplastic

0.65 – 3.55.58.014

22 – 3038 – 100101 – 250251 – 500

(a)0.800.801.201.601.602.002.402.80

(b)0.400.500.800.801.001.301.601.80

(a) None

(b) Nylon jacketor equivalent

Paper 85°C For underground serviceconductors, or by specialpermission

Paper Lead sheath

Perfluoro-alkoxy

PFA 90°C

200°C



Perfluoro-alkoxy 2.0 – 5.58.0 – 3038 – 100

0.500.801.20

None

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Perfluoro-alkoxy

PFAH 250°C Dry locations only.Only for leadsWithin apparatusor within raceways

connected to apparatus(nickel or nickel-coated

copper only)

Perfluoroalkoxy 2.0 – 5.58.0 – 3038 –100

0.500.801.20

None

Thermoset

Thermoset

RH

RHH

75°C

90°C



Flame-retardantthermoset

2.0 – 3.5d

5.58.0 – 3038 –100

101 – 250251 – 500

501 – 1 000For 601 – 2000

Volts, seeTable

3.10.1.62

0.801.201.602.002.402.803.20

Moistureresistant,

flame-retardant,nonmetalliccovering1

Moisture-resistantthermoset

RHWe 75°C Dry and wet locationsWhere over 2 000 voltsInsulation, shall beOzone resistant

Flame-retardant,moisture-resistantthermoset

2.0 – 5.5dd

8.0 – 3038 –100

101 – 250251 – 500501 – 1 000

For 601 – 2000Volts, see

Table3.10.1.62

1.201.602.002.402.803.20

Moistureresistant,

flame-retardant,nonmetalliccovering5

aSome insulations do not require an outer covering.bWhere Design conditions require maximum conductor operating temperature above 90 oCcFor signaling circuits permitting 300-volts insulation.dFor size 2.0 – 3.5 mm2, RHH insulation shall be 1.20 mm thickness.eListed wire type designated with the suffix “-2”, such as RHW-2, shall be permitted to be used at continuous 90 oC operating temperature, wet or dry.fSome rubber insulations do not require an outer covering.

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Table B1. (Continued)

Trade NameTypeLetter

MaximumOperating

Temperature

ApplicationProvisions

InsulationOuter

CoveringaMaterials ConductorArea (mm2)

Thickness(mm)


RHW-2 90°C Dry and wet locations Flame-retardant,moisture-resistantthermoset

2.0 – 5.58.0 – 3038 – 100101 – 250251 – 500

501 – 1 000For 601 – 2 000

Volts, seeTable

3.10.1.62

1.201.602.002.402.803.20

Moisture-resistant,flame-retardant,nonmetalliccoveringf

Silicon SA 90°C

200°C


For special applicationb Silicon rubber

2.0 – 5.58.0 – 3038 – 100101 – 250251 – 500

501 – 1 000

1.201.602.002.402.803.20

Glass or othersuitable braidmaterial

Thermoset SIS 90°C Switchboardwiring only

Flame-retardantthermoset

2.0 – 5.58.0 – 3038 – 100

0.801.202.40

None

Thermoplasticand fibrousouter braid

TBS 90°C SwitchboardWiring only

Thermoplastic 2.0 – 5.58.0

14 – 3038 – 100

0.801.201.602.00

Flame-retardant,nonmetalliccovering

Extendedpolytetrafluoro-ethylene

TFE 250°C Dry locations only. Only forleads within apparatus orwithin raceways connectedto apparatus,or as openwiring (Nickel or nickel-coated copper only)

ExtrudedPolytetrafluoro-ethylene

2.0 – 5.58.0 – 3038 – 100

0.500.801.20

None

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Heat-resistantthermoplastic

THHN 90°C Dry and damp location Flame- retardant,heat-resistantthermoplastic

2.0 – 3.55.5

8.0 – 1422 – 30

38 – 100125 – 250251 – 500

0.400.500.801.001.301.601.80

Nylon jacketor equivalent

Moisture-andheat-resistantthermoplastic

THHW 75°C

90°C

Wet location

Dry location

Flame-retardant,moisture- and heat-resistantthermoplastic

2.0 – 5.58.0

14 – 3038 – 100101 – 250251 – 500

0.801.201.602.002.402.80

None


THWc 75°C

90°C


Special applications withinelectric discharge lightingequip. Limited to 1 000open –circuit volts or less(size 2.0 – 8.0 mm2 only aspermitted in Section4.10.6.10)

Flame-retardant,moisture- and heat-resistantthermoplastic

2.0 – 5.58.0

14 – 3038 – 100101 –250251 – 500

501 – 1 000

0.801.201.602.002.402.803.20

None


THWNe 75°C Dry and wet locations Flame-retardant,moisture- and heat-resistantthermoplastic

2.0 – 3.55.5

8.0 – 1422 – 30

38 – 100125 – 250251 – 500

0.400.500.801.001.301.601.80

Nylon jacketor equivalent

aSome insulations do not require an outer coveringbWhere design conditions require maximum conductor operating temperature above 90°CeListed wire type designated with the suffix “-2”, such as RHW-2, shall be permitted to be used at a continuous 90°C operating temperature, wet or dry.fSome rubber insulations do not require an outer covering.

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Table B1. (Continued)

Trade NameTypeLetter

MaximumOperating

TemperatureApplicationProvisions

InsulationOuter

CoveringaMaterials ConductorArea (mm2)

Thickness(mm)

Moisture-resistant

thermoplastic

TW 60 C Dry and wet locations Flame-retardant,Moisture-resistantThermoplastic

2.0 – 5.58.0

14 – 3038 – 100

101 – 250251 – 500

501 – 1 000

0.801.201.602.002.402.803.20

None

Undergroundfeeder andbranch-circuitcable —singleconductor

(For Type UFcable employingmore than oneconductor, seeArticle 3.39.)

UF 60°C See Article 3.39 Moisture-resistant 2.0 – 5.58.0 – 3038 – 100

1.60g

2.00g

2.40g

Integral withinsulation

75°C Moisture- andheat- resistant

Undergroundservice-entranceCable — singleconductor(For Type USEcable employingmore than oneconductor, seeArticle 3.38.)

USEe 75°C See Article 3.38. Heat- and moisture-resistant

2.0 – 5.58.0 – 3038 – 100

101 – 250251 – 500

501 – 1 000

1.201.602.002.402.803.20

Moisture-resistantnonmetalliccovering

[(See3.38.1.1(b)]

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Thermoset XHH 90°C Dry and damp locations Flame-retardantthermoset

2.0 – 5.58.0 – 3038 – 100

101 – 250251 – 500

501 – 1 000

0.801.201.401.702.002.40

None


XHHWe 90°C Dry and damp locations

Wet locations

Flame-retardantmoisture-resistantthermoset

2.0 – 5.58.0 – 3038 – 100

101 – 250251 – 500

501 – 1 000

0.801.201.401.702.002.40

None


XHHW-2 90°C Dry and damp locations Flame-retardantmoisture-resistantthermoset

2.0 – 5.58.0 – 3038 – 100

101 – 250251 – 500

501 – 1 000

0.801.201.401.702.002.40

None

Modifiedethylenetetrafluoro-ethylene

Z 90°C

150°C



Modified ethylenetetrafluoro-ethylene

2.0 – 3.55.5

8.0 – 2230 –38

50 – 100

0.400.500.640.891.20

None

Modifiedethylenetetrafluoro-ethylene

ZWe 75°C

90°C

150°C

Wet locations



Modified ethylenetetrafluoro-ethylene

2.0 – 5.5 8.0 – 30 None

aSome insulations do not require an outer covering.bWhere design conditions require maximum conductor operating temperatures above 90°C.eListed wire types designated with the suffix “2,” such as RHW-2, shall be permitted to be used at a continuous 90°C operating temperature, wet or dry.gIncludes integral jacket.iInsulation thickness shall be permitted to be 2.80 mm for listed Type USE conductors that have been subjected to special investigations. The nonmetallic covering over individual rubber-covered conductors ofaluminum-sheathed cable and of lead-sheathed or multiconductor cable shall not be required to be flame retardant. For Type MC cable, see 3.30.3.1. For nonmetallic-sheathed cable, see Part 3.34.3. For TypeUF cable, see Part 3.40.3.

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165

ANNEX C

Philippine National Standard for Electrical Products

1. PNS 35-1:2004 - Electric wires and cables – Thermoplasticinsulated electric copper wires and cablesrated 600 volts – Part 1: Generalspecifications

2. PNS 35-2:2006 - Electric wires and cables – Thermoplasticinsulated electric copper wires and cablesrated 600 volts – Part 1: Non-metallic flatjacketed electric wires – Specifications

3. PNS 40:1984 - Electric wires and cables – Copperredraw rod for electrical purposes –Specification

4. PNS 43:1984 - Electric wires and cables – ECAmendments 01: aluminum redraw rod for electrical1985 purposes – Specification

5. PNS 106:1987 - Enameled copper wires – Test method6. PNS 107:1987 - Polyurethane enameled copper wires,

class 105 – Specifications7. PNS 108:1987 - Polyester enameled copper wires, class

105 – Specification8. PNS 109:1987 - Polyvinyl formal enameled copper wires,

class 105 – Specification9. PNS 110:1987 - Polyester amide-imide enameled copper

wires, class 180 - Specification10. PNS 111:1987 - Oleo-resinous enameled copper wires –

Specification11. CDPNS 163:XXXX - Electrical products – Polyvinyl chloride

insulated flexible cords and fixture wires– Specification

12. PNS 260:2004 - Electric wires and cables – Annealedcopper wires – Specification

13. CDPNS 261:XXXX - Electric wires and cables – PVCinsulated low voltages cable for roadvehicles – Specification


166

14. CDPNS 661:XXXX - Organic chemicals – PlasticizedPolyvinyl chloride compounds forelectrical insulation – Specification

15. PNS 662:1992 - Electrical wires and cables – Ampacitiesof insulated electric 8u77 conductors,0-35,000 volts

16. PNS 1086:1992 - Electrical wires and cables – Hard-drawn solid copper wires for electricalpurposes – Specification

17. PNS 1087:1992 - Electrical wires and cables – Hard-drawncopper stranded – Specification

18. PNS 1088:2006 - Electric wires and cables Copper andaluminum conductors for electricalpurposes – Test methods

19. PNS 1129:1993 - Hard-drawn aluminum wires for electricpurposes – Specifications

20. PNS 1130:1993 - Hard-drawn aluminum strandedconductors – Specification

21. PNS 1207:2006 - Electric wires and cables – Soft-drawn(annealed) copper stranded conductorsfor electrical purposes – Specification

22. PNS 1289:1995 - Electric wires and cables – PVCinsulated battery cables – Specification

23. PNS 1487-1-1:1997 - Common test methods for insulating andsheathing materials of electric cables –Part 1: Methods for general application –Section 1: Measurement of thickness andoverall dimensions – Test fordetermining mechanical properties

24. PNS 1487-1-2:1997 - Common test methods for insulating andsheathing materials of electric cables –Part 1: Methods for general application –Section 2: Thermal ageing methods

25. PNS 1487-1-3:1997 - Common test methods for insulating andsheathing materials of electric cables –Part 1: Methods for general application –Section 3: Methods of determining thedensity – Water absorption tests –Shrinkage


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26. PNS 1487-1-4:1997 - Common test methods for insulating andsheathing materials of electric cables –Part 1: Methods for general application –Section 4: Test at low temperature

27. PNS 1487-2-1:1997 - Common test methods for insulating andAmendments 01 & sheathing materials of electric cables –02:1997 Part 2: Methods specific to elastomeric

compounds – Section 1: Ozone resistancetest–hot set test–Mineral oil immersiontest

28. PNS 1487-3-1:1997 - Common test methods for insulating andsheathing materials of electric cables –Part 3: Methods specific to PVCcompounds – Section 1: Pressure test athigh temperature – Test for resistance tocracking

29. PNS 1487-3-2:1997 - Common test methods for insulating andsheathing materials of electric cables –Part 3: Methods specific to PVCcompounds – Section 2: loss of mass test– Thermal stability test

30. PNS 1487-4-1:1997 - Common test methods for insulating andsheathing materials of electric cables –Part 4: Methods specific to polyethyleneand polypropelene compounds – Section1: Resistance to environmental stresscracking – Wrapping test after thermalageing in air – Measurement of the meltflow index – carbon black and/or mineralcontent measurement in PE

31. PNS 1487-4-2:1997 - Common test methods for insulating andsheathing materials of electric cables –Part 4: Methods specific to polyethyleneand polypropelene compounds – Section2: Elongation at break after pre-conditioning – Wrapping test afterthermal ageing in air – Measurement ofmass increase – Long term stability test –(Appendix A) – Test method for copper-


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catalysed oxidative degradation(Appendix B)

32. PNS 2048:2006 - Electric wires and cables –Thermoplastic-insulated undergroundfeeder - Specification

33. PNS ASTM B230: - Standard Specification for Aluminum2005 1350-H19 Wire for Electrical Purposes

(ASTM published 2004)34. PNS ASTM B231: - Standard Specification Concentric-Lay-

2005 Stranded Aluminum 1350 Conductors(ASTM published 2004)

35. PNS ASTM B233: - Standard Specification for Aluminum2005 1350 Drawing Stock for Electrical

Purposes (ASTM published 2003)36. PNS ASTM B400: - Standard Specification for Compact

2005 Round Concentric-Lay-StrandedAluminum 1350 Conductors(ASTM published 2004)

37. PNS ASTM B609: - Standard Specification for Aluminum2005 1350 Round Wire, Annealed and

Intermediate Tempers, for ElectricalPurposes (ASTM published 2004)

38. PNS ASTM B786: - Standard Specification for 19 Wire2005 Combination Unilay-Stranded

Aluminum Conductors for SubsequentInsulation (ASTM published 2004)

39. PNS ASTM B800: - Standard Specification for 8000 Series2005 Aluminum Alloy Wire for Electrical

Purposes-Annealed and IntermediateTempers (ASTM published 2000)

40. PNS ASTM B801: - Standard Specification Concentric-Lay-2005 Stranded Conductors of 8000 Series

Aluminum Alloy for SubsequentCovering or Insulation (ASTMpublished 1999)

41. PNS ASTM B172: - Standard Specification for Rope-Lay-2005 Stranded Copper Conductors Having

Bunch-Stranded Members, for ElectricalConductors (ASTM published 2001)


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42. PNS ASTM B173: - Standard Specification for Rope-Lay-2005 Stranded Copper Conductors Having

Concentric-Stranded members, forElectrical Conductors (ASTM published2001)

43. PNS ASTM B174: - Standard Specification for Bunch-2005 Stranded Copper Conductors for

Electrical Conductors(ASTM published 2002)

44. PNS ASTM D1047:- Standard Specification for Poly(Vinyl2005 Chloride Jacket for Wire and Cable

(ASTM published 2001)45. PNS ASTM D1351:- Standard Specification for

2005 Thermoplastic Polyethylene Insulationfor Electrical Wire and Cable(ASTM published 2002)

46. PNS ASTM D2219:- Standard Specification for Poly(Vinyl2005 Chloride) Insulation for Wire and Cable,

60OC Operation(ASTM published 2002)

47. PNS ASTM D2220:- Standard Specification for Poly(Vinyl2005 Chloride Insulation for Wire and Cable,

75OC Operation(ASTM published 2002)

48. PNS ASTM D2308:- Standard Specification for2005 Thermoplastic Polyethylene Jacket for

Electrical Wire and Cable(ASTM published 2002)

49. PNS ASTM D3554:- Standard Specification for Track-2005 Resistant Black Thermoplastic High-

Density Polyethylene Insulation forWire and Cable, 75OC Operation(ASTM published 2001)


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171

Annex D


173

Bibliography

1) Electric Cables Handbook 3rd Edition by Moore (Blackwell,1997)

2) Cable handbook by Phelps Dodge Philippines3) National Electrical Code4) Philippine Electrical Code5) Wikipedia


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power cables and wires technical manual 2010 edition

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