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3-1. Basic safe working practicesBasic safe workin g practices require th at t he workerbe in good health, not under the influence of drugsor alcohol, free of major em otiona l, psychological, an dfinancial problems, familiar with the fundamentalsof Safety, familiar with equipmen t a nd tool use, wellprepared for each job, and always alert and respon-sible for his/her acts.

3-2. Fundamentals of safetyThe funda men ta ls of safety include a ccident pr even-tion and hazar dous work elimination.

a. Accident prevention. ACCIDENTS DO NOTJUST HAPPENAccidents are the result of un-safe acts, un safe conditions, or both.

(1) Unsafe acts , which cause a lmost 9 out of every 10 a ccidents, include

(a) Operating without au thority or war ning,such a s opening or closing switches, circuit br eaker sor reclosers without permission; operating hoists,tr ucks, or other motor-operated devices without giv-ing a proper wa rn ing; failur e to place warn ing signsor guar ds or to give signals wher e needed; and viola-tion of red ta gging ru les.

(b) Mak ing safety devices inopera tive unn ec-essarily or without a n a dequate reason, such as r e-moving guards, using oversize fuses, and blockingprotective devices.

(c) Using unsafe equipment or using equip-ment improperly, such as using tools an d chisels th atar e dama ged, using pipe extensions on wren ches notdesigned for t hem, u sing th e wrong tools for t he job,and using your han ds instead of hand tools.

(d ) Unsafe loading or placing objects, suchas carrying or lifting heavy loads, placing objects

where they are l ikely to fall , unstable packing of loads , and fa i lure to b lock or guard equipmentagainst unexpected movements.

(e) Taking unsafe posit ions, such as work-ing or l i f t ing f rom an improper posi t ion; casualwalking under suspended loads , through hazard-ous work areas, or close to openings; entering ar-eas cont amina ted by gases or fumes wi thout ta k-ing proper precaut ions; and r id ing in un safe loca-tions in or on m otor vehicles.

CHAPTER 3CHAPTER 3CHAPTER 3CHAPTER 3CHAPTER 3BASIC PERSONNEL SAFE WORKING PRACTICESBASIC PERSONNEL SAFE WORKING PRACTICESBASIC PERSONNEL SAFE WORKING PRACTICESBASIC PERSONNEL SAFE WORKING PRACTICESBASIC PERSONNEL SAFE WORKING PRACTICES

(f) Working near live equipment , moving machin-ery, apparatus, or moving parts thereof, without observ-ing prescribed safety precaut ions or r egulations, or with -out using r equired protective devices an d equipment .

(g) Distracting or st art ling acts, such as pr ac-tical joking, horseplay, teasing, qua rr eling, an d an -noying behavior.

(h ) Fa ilure to use personal protective equip-men t or sa fe clothing, such as ru bber gloves, aprons,and leggings where required.

(2) Unsafe condi t ions , inc lude

(a) Lack of shields or gua rds a nd un bar ricadedfloor openings or excava tions.

(b) Insufficient warning signs, inadequateguar ds for t he job, ma keshift barr iers, and red t ags:not pr operly applied.

(c) Defective mat erial or equipmen t, such asbroken pieces, stripped threads, split handles, anddam aged tools.

(d ) Ha zardous arra ngement s, resulting frompoor housekeeping or lack of plann ing.

(e) Unsafe personal apparel, such as neck-ties, jewelry, an d loose sleeves, when w orn n ear mov-ing ma chinery.

(f) Improper illum inat ion or ina dequat e ven-tilation when working in a ma nh ole or u tility room.

b . H a za rd ou s w or k el im i n a t ion . H a z a r d o u swork can be eliminated when workers are instilledwith t he ha bit of being cau tious:

(1) Do not begin work around energized ma-chinery or equipment or at any place where a h az-

ard exists until adequate l ighting and all propersafety measures are provided. When finished, dis-conn ect an d rem ove all extens ion power cords . Neverleave exten sion cords wh ich a re n ot in use.

(2) Place DANGER signs where condi t ions re-quire their use.

(3) Remove DANGER signs f rom places wherethe danger no longer exists; do not use such signsunnecessarily.

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(4) Inspect a l l tools and equipment before us-ing them a nd r eport promptly an y defect n oticed.

(5) Never work so closely to fellow workers t hatth ey may be enda ngered by swinging picks, shovels,or similar tools.

(6) Use nai l pul lers when removing nai ls from

boxes or crat es.

(7) Do not use fi les without proper handles .

(8) Use cr ibbing or other approved means tosupport objects ra ised above a working position. Donot depen d upon a lifting jack for su pport.

(9) Do not s tand or a l low others to s tand nearropes or cables un der str ain.

(10) Stop port able gasoline engines or electr icmotors propelling equipmen t su ch as concrete m ix-

ers, compressors, pumps, blowers, and cranes, be-fore refueling, greasing, oiling, or repairing.

(11) When bur ning insulation off scrap wire:

(a) Use a n incinera tor, if available. If an in-ciner at or is not available, burn ing should be done inthe open a way from bu ildings and flammable mat e-rial. Obey local civil laws regarding open fires.

(b) Use iron forks t o han dle wire.

(c) Let th e fire bur n out before rem oving thewire.

(12) Report promptly and establish guards overany hazardous condition which might cause injury,property damage, or interference with electric ser-vices. This includes a ll hazar ds, such a s fallen wires,open holes or ditches, an d broken poles or crossar ms.

(13) Keep away from dangerous places unlessthe work requires you to be there.

(14) Treat a ll electric wires and a ppara tus as

dangerous and do not t ouch su ch equipment unlessyou a re qua lified and a uth orized to handle such work.

(15) Do not install fuses which are of an im-proper type or capacity.

(16) Do not operat e porta ble electr ic ha nd dr ills,hand grinders, hand buffing wheels, or other simi-lar equ ipment un less the m otor casing is effectivelygrounded or th e tool is pr operly labeled as doubleinsulated.

(17) Casings of electr ic motors m oun ted on work benches or m ounted on met al bases fasten ed to con-crete, wood, or metal f loors must be effectivelygrounded before operation.

(18) Do not remove broken light bulbs whileworking inside tan ks, heat ers, boilers, and other suchenclosed spa ces u nless t he cord is disconn ected from

the su pply outlet . Empt y sockets a re n ot perm ittedin such pla ces.

(19) After a nat ura l disaster such as flood, fire,torna do, hu rr ican e or ear th qua ke all electr ical com-ponents and devices such as swi tchgear, c i rcui tbreak ers, fuses, tra nsform ers, reclosers, genera tors,electric machines, electric equipment and electriccircuits m ust be checked an d test ed by professiona lsbefore re-energizing.

(20) Before st art ing an electrical job th e work-ing areas must be checked for safety. Accessible

routes for emergency entrance and exit should beavailable. All obsta cles mu st be r emoved an d all un -safe situa tions mu st be fixed before job can be st ar ted.Unsafe personal apparel such as neckties, jewelry,wat ches, and loose clothes sh ould not be worn. Per-sonal pr otective devices su ch as safety gloves, ru b-ber blan kets, h ot sticks, goggles should be a vailablean d rea dy for use. The workplace must be pr otectedfrom unauthorized access and unforeseen accidentsby one of th e following m ean s:

(a ) Warn ing equ ipmen t . Adequat e barr iers,warning signs, traffic cones, and lights must be lo-cated on appr oaches to and at the work a reas, exca-vations, open ma nh oles, par ked equipment ; an d oth erhazar ds. Special precaut ions m ust be taken for anyar eas wh ere redu ced visibility occurs su ch as n ightoperations or in fog. Warning devices must be re-moved when t he work is completed.

(b) Flagm en . Flagmen a re necessary whenwarning devices are not adequat e such as in tr afficcontr ol. Flagmen mu st wear sa fety warn ing vests,operate t wo-way ra dios an d carry war ning signs fortheir protection and work area protection.

3-3. Normal environmental impactsThe environment may cause impacts on t he work tobe performed and potential h ealth hazards for work-ers when careless or lack of site prepa ra tion exists.

a. Working in elevated positions. A safety ropeshould be used to att ach to the worker 's body whenhe/she is in a n elevated position. To prevent t he pos-sibility of dropping materials or tools from the el-evated position onto people underneath, appropri-

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ate signs and guards must be used to keep peopleaway. The supporting platforms for workers, tools,and m aterials must be strong and ba lanced for th eloads they carry to prevent the risk of breaking orfalling.

b. Working in conf ined spaces . A confin ed sp aceis an enclosed space with restricted access and in-

sufficient ventilation such as vaults, manholes, ortanks. Insufficient ventilation can result in danger-ous air contamination and an oxygen deficient at-mosphere . Dangerous a i r con tamina t ion r e su l t swhen there is a flammable gas or vapor exceeding10 percent of its lower explosive limit. An oxygendeficient a tmospher e contains less th an 19.5 percentoxygen by volum e.

(1) Before ent ering in to a con fi ned spa ce. Priorto entering a confined space, the atmosphere will betested by qualified personnel to determine its safetyusing approved combustion gas/oxygen detectors and

recording the results. Where tests indicate an unsafeat mospher e, forced vent ilation will be provided an d nowork will be star ted un til safety ha s been assur ed byadditiona l tests. An adequa te continu ous supply of airwill be provided wh ile work is being done.

(2) Em ergen cy cas e. Ent ry may be made intoa confined space with an unsafe atmosphere if re-quired in a n emer gency but only if th e worker is us-ing a supplied air respirator or gas ma sk if there isadequate oxygen. Always use a safety lifeline andhave a second worker standing by when an emer-gency ent ry is made.

(3) Safety protection. When working in a con-fined spa ce th at contain s exposed energized part s, aworker must use protective shields, protective bar-riers, and insulating mat erials as n ecessary to avoidinadvertent conta ct with t hese par ts. Doors, hingedpanels, and the like should be secured to preventcont act with exposed energized part s.

c. Working in noisy areas. Protection against t heeffects of noise exposure sh ould be pr ovided for facil-i ty workers whenever the noise level exceeds theperm issible limits shown in t able 3-1.

(1 ) N oi se l ev el eq u iva l en t s . As a ru l e o f thu mb, for a norma l conversation tha t can be hear dat about 2 feet (0.6 meter s) dista nce, the n oise levelis probably less th an 90 decibels, the point a t wh ichprolonged exposure can cause a gradual decay inhea ring a bility. Noise which is similar t o the soundof firing from a rifle or sh otgun is considered as animpulse type when ma ximum variation in sound levelexceeds 1 second.

(2) Occupational Safety and H ealth Ad m inis-tration (OSHA) requirements. Table 3-1 providesth e perm issible noise exposur e expressed in decibels(for sound levels) versu s h ours (for t ime du ra tion).Exceeding th ese limits, OSHA requires tha t engineer-ing noise controls, administrative controls, or per-sonal hearing protective equipment be used. Onlythose hearing protectors that have been tested ac-

cording to American National Standards Insti tute(ANSI) S3.19 will be accepta ble. Ear insert deviceswill be fitted individually by a competent person.Plain cott on is not a ccepta ble as a protective device.When the sound pressure level in a working areaexceeds 115 decibels stea dy sta te, persona l ear pr o-tection equivalent to th e combinat ion of earplugs a ndear muffs shall be required.

(3 ) N oi se lev el m ea su rem en t s. Noise levelmeasurements should be made by qualified person-nel using calibrat ed instrum ents.

(4) Caution signs. Hazar dous noise level areas(greater than 85 decibels continuous or 140 decibelsimpulse) should be mar ked with cau tion signs indicat-ing both the presence of hazardous noise levels andth e need for hear ing protection.

Table 31. OSHA Permissible Noises Exposures

Dura tion per Day (Hours)

8

6

4

3

2

1+1/2

1

1/2

1/4 or Le ss

Sound Level (Decibels)

90

92

95

97

100

102

105

110

115

Note: When t he da ily noise exposure is composed of two or m oreperiods of noise exposur es of differen t levels, their combined ef-

fect should be considered, rather than the individual effect of each. If th e su m of the following fractions: C l /T l + C 2 /T 2 + ... + C n / T n exceeds unity; then, th e mixed exposur e should be consideredto exceed th e limit value. C n indicates th at t otal time of exposureat a specified noise level, an d T n indicates t he tota l time of expo-sure permitted at th at level.

d. Working in insuff ic ient ly i l luminated areas .Safety rules require adequate illumination for thework area . Wher e nat ur al or inst alled art ificial illu-mination is not sufficient temporary lighting mustbe provided. En sure tha t t emporar y l ighting is not

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powered from the same circuit as temporary recep-ta cles. The u se of ma tches or open flames t o providesuch il lumination is forbidden. OSHA requires aminimum of a 5 footcandle (or 54 lux) level in con-str uction a reas an d a 10 footcan dle (or 108 lux) levelin electr ical equipmen t r ooms.

(1 ) S p a c e s c on t a i n i n g e x p o s ed e n e rg i z e d

part s. Do not en ter spaces cont aining exposed en-ergized part s un less illumina tion is provided. Do notperform tasks near exposed energized parts wherelack of illum inat ion or a n obstr uction p recludes ob-servat ion of the work to be perform ed. Do not reachblindly into area s which ma y contain en ergized par ts.

(2) Tem porary lightin g. All lamp s for gen era l il-lumina tion will be protected from accidenta l cont actor break age using approved guards. Guar ds are n otrequired for flashlights. Flashlights will not havemetal cases. All l ight metal case sockets will begrounded. Temporary lights will not be suspended

by their electric cords unless cords and lights aredesigned for t his m eans of suspen sion. P ortable elec-tric lighting used in wet or other conductive loca-tions will be operated at 12 volts or less. However,120-volt lights m ay be u sed if protected by a gr oundfault circuit inter ru pter. On ly explosion-proof light -ing equipmen t will be us ed in confined or enclosedspaces unless atmospheric tests have proven thespace to be nonexplosive.

3-4. Hazardous environmental impactsSerious bodily harm can result from contact withhazardous materials such as asbestos, polychlori-na ted biphen yls (PCB), and su lfur h exifluoride (SF 6).These ha zardous ma terials can be foun d in old build-ing insu lation mater ial, ut ility substa tion, old tra ns-formers, capacitors, circuit breakers, switches, andvo l t age r egu la to r s . They shou ld be t r ea t ed andhandled Environmental Protection Agency (EPA)regulations. Wood preservative treatment productswould also require special ha ndling because of theirtoxicity. The following paragraphs will describe thedangers of these hazardous materials, where theyare u sed, and how to han dle them. Protective appareland accessories are covered in paragraph 4-3. The

effects of electromagnetic fields (EMF) created byhigh volta ge electr ic lines will also be discussed. Re-quirements for protection against nuclear radiationar e beyond the scope of th is man ua l.

a. Working in asbestos areas. Asbestos ha d beenused in years past as insulation and fire protectionmaterial. However, cutting asbestos materials willrelease a sbestos fibers to the a tm osphere. These fi-bers will become harmful if they are breathed intothe lungs. The cells within the lungs will try to re-

move these fibers bu t will not succeed. Scar t issueswill form in t he lun gs. Studies have shown th at s ig-nificant quantity of asbestos fibers in the lung cancause lung cancer. For these reasons asbestos con-taining products ar e banned from th e mark et. How-ever, electr ical worker s st ill have a chance to be ex-posed to such fibers if th e existing asbest os contain-ing products su ch as ceiling t iles or cement-asbestos

condu its in some old buildings ar e accidenta lly cut .Therefore, before star ting a job in an ar ea wher e as-bestos is identified, a writt en plan deta iling compli-an ce with Occupa tional Safety and H ealth Adminis-tration (OHSA) and the Environmental ProtectionAgency (EPA) a sbes tos aba temen t r equ i remen ts h o u l d b e d e v e l o p e d a n d s u b m i t t e d t o t h eGovernment ' s des ignated author i ty. No asbes toswork shall be perm itted without appr oval from theGovernment 's authority. The disposal of asbestoscontaining products shall be handled by qualifiedpersonnel or contractors according to all Federal,State and local regulations.

b. Working wi th polychlor inated b iphenyl lPCB)containing products. Because of their insulatingand nonflammable properties, PCB has been usedin years pa st a s heat excha nge an d dielectric fluid inpower transformers, capacitors, voltage regulators,an d circuit brea kers. Trade na mes for PCBs includeAroclor, Askarel , Eucare l , Pyranol , Chlorextol ,Nepolin, among others. PCBs can enter the air byvaporization from a leaking container. When in airPCBs will travel by wind. PCBs will then enter thesoil and water. Studies have shown tha t P CBs cancause serious skin diseases, liver failure, birth de-fects, and r etar dat ion. In 1977 the U.S. Environmen-ta l Pr otection Agency (EPA) banned th e pr oductionof PCBs. The National Insti tute for OccupationalSafety and Health (NIOSH) recommends that theworkers not be in any workplace where the air con-tains more than 0.001 milligrams of PCB per cubicmeter for a 8-hour workday, 40-hour workweek.Workers sh ould be awar e of all locations ha ving PCBcont ainin g products an d who to contact if there is aspill. The transportation, storage, and disposal of PCB cont aining pr oducts should be according to thecurrent EPA regulations.

(1) H an d li ng. PCB is a str ong solvent an da pr olonged contact will resu lt in removing the na tu -ral skin oils. All PCB fluid shall be placed in closedcontainers and handled by qualified personnel.

(2) Persona l p rotection. Nonabsorbent gloves(neoprene, teflon, viton, etc.), footwear, masks, andappr opriate pr otective cloth ing should be worn wh enha ndling P CBs. All exposed pa rt s of the body shouldbe greased with either petr oleum jelly (vaseline), ol-

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ive oil, cold cream, or another approved skin com-pound. At locat ions wh ere t here is not su fficient ven-tilation, workers must, in addition, use organic va-por respira tors an d goggles.

(3 ) E m ergen cy ca se. In case of emergencywhen a worker comes accidentally in contact withPCB liquid he/she should immediately wash it off

with soap an d water.

c. Wor k i n g w i t h s u l fu r h ex i fl u or i d e (S F 6 )containers. In i ts pure sta te, SF 6 is a colorless, odor-less, tast eless, nonflamm able, nontoxic, an d n oncor-rosive gas sh ipped in liquid form. Since it is five timesheavier th an air, i t can act as an asphyxiant , and ina liquid stat e, it can cause t issue freezing similar t ofrost bite. Its decomposition products, which r esultfrom an electric arc or short-circuit, can be toxic.These decomposition pr oducts will recombine to formSF 6 gas or be removed by an absorber provided fortha t pur pose within such equipment as circuit break-

ers and switches. SF 6 gas can leak and should al-ways be treat ed as hazar dous.

(1) Hand li ng. Only qualified worker s tr ainedto deal with SF 6's ha zardous effects can an alyze, fill,and reclaim th is mater ial. Only when spills and leaksoccur, should facility personnel be involved to pro-tect the pu blic an d th e workpla ce.

(2) Di sp ers in g. No employee will work alonewhen dispers ing SF 6. Wear approved insula t inggloves, safety glasses, and appropriate protectiveclothing to prevent any skin contact. Remove allsources contributing to electrical arcing and heat.Provide adequate ventilation to prevent the atmo-sph ere from becoming oxygen deficient (19.5 per centby volume of oxygen minimum). Wear a hood withan air su pply line wh en ent ering an oxygen-deficientat mosphere or where a n oxygen detector is not avail-able to test air. Chemical cartridge respirators willnot be used. Provide a safety l ine and a standbyworker ha ving another h ood with a n a ir-line as back-up for th e worker in the h azardous SF 6 atmosphere.

(3) In case of f ir e. Though a non-inflamm ablegas, SF

6can decompose at high tem perat ures to yield

toxic and corrosive byproducts. If a fire occurs, usean appr opriate fire extinguishin g agent. All fire fight-ers should wear correct breathing appa rat us.

d . Wor k i n g w i t h w o od p r es er v at i ve t rea t m e n t prod u ct s. Creosote and water-borne or oil-bornepreservatives used for wood treatment can only behandled by certified pesticide applicators. Coppernaph then ate preservative trea tment does not requirecertification for its use.

e. Wor k a rou n d e l ect r ic a n d m a g n et i c fi eld s. This section covers safety measures whenworking ar ound electric an d ma gnetic fields producedby high -volta ge electric lines. A 60-hert z electric lineemits a n extremely low frequency (ELF ) electr omag-net ic field (EMF) wh ich ha s n onionizing ra ys. So far,no conclusive evidence has been pr oved th at t he EMFfrom ELF sources are ha rm ful. OSHA an d EPA ha ve

not concurred that prudent avoidance which con-sists of ta king steps t o keep hum an s out of such fields,is necessary.

(1) E lect ri c field . Whenever th ere is a voltagedifference between two conductive objects such astwo cond uctors , an electric field will be developed inth e space between t hese t wo conductive objects. Thema gnitu de or str ength of th e electr ic field is propor-tional t o the d ifferen ce of voltages bet ween t he t wocondu ctive objects an d invers ely proport iona l to th edista nce from th e object. Electric fields are mea sur edin volts per m eter (v/m). The h igher t he difference of

voltages between two conductive objects and theshorter th e distan ce from th e object th e stronger willbe th e electric field.

(2) M agn et ic fi eld . Whenever t here is a cur-rent flowing through a conductor or a coil of wirewound around a piece of iron (or a permanent mag-net called the electr omagn et) , a m agn etic field willbe developed in t he spa ce ar ound th e conductor andbetween t he t wo ends of th e coil. The m agnitu de orstr ength of th e ma gnetic field is proportiona l to themagnitude of the current flowing through the con-ductor (or t he coil) and invers ely proport iona l to th esqua re of the dista nce from th e condu ctor or t he coil.Magnet ic fields ar e mea sur ed in Ga uss (G), or Tesla(T) (where one Tesla is equa l to 10,000 Gaus ses). Thelarger t he curr ent flowing thr ough th e conductor orthe coil and the shorter the distance from the con-ductor or th e coil, th e str onger will be the m agnet icfield.

(3) E ff ects on h um an bod y. Electric fields willbe greatly reduced in strength by obstacles such asbuildings, tr ees, vehicles an d so on. Ma gnet ic fields onth e other h an d cannot be blocked by obstacles but canbe greatly reduced by the distan ce. Some recent st ud-ies have shown tha t th e risks of can cer a nd leukemiaare higher for people living near high voltage trans-mission lines. These health problems a re su spected tobe caused by th e ma gnetic fields genera ted by t he elec-tr ic lines. However, no scientist s ar e certain of th e causeof the disease because the en ergy radiated by th e mag-netic field is very sma ll as compa red t o the en ergy ra-diated by X-rays. The magnetic field energy does notha ve enough st rength to break t he bonds in th e cells of huma n body to cause cancer or dea th .

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The International radiation Protection Association(IRPA) has also set some guidelines on electric and mag-net ic fields exposures for electrical worker s (See table 33).

The American conference of governmen t Indu str ialHygienist s (ACGIH ) has a lso set some guidelines forpacemaker worker s. (See table 34).

Table 33. IRPA Guidelines on Electric and Magnetic FieldExposures

Exposures

Occupational:

-Whole working day

-short-term (*)

General Public

-Whole working day

-Short-term (*)

Electric F ields Magnetic Fields

50Hz

10kV/m

30kV/m

5kV/m

10kV/m

60Hz

10kV/m

30kV/m

5kV/m

10kV/m

50Hz

5G

50G

1G

10G

60Hz

5G

50G

1G

10G

Note: (*) For short term, electric field strength (kV /m) x hoursexposure should not exceed 80. Whole body exposure to magnetifields up to 2 hours per day should not exceed 50G.

Table 34. ACGIH Guidelines on Electric and Magnetic FieldExposures for Pacemakers

Exposures

Occupational:

Cardiac Pacemaker

Electric F ields Magnetic Fields

50Hz

15kV/m

15kV/m

60Hz

15V/m

15kV/m

50Hz

10G

1G

60Hz

10G

1G

Note: Protective devices such as shielded clothing, gloves, insula-tion bucket liners and so on, should be used where the electric fi15kV / m or larger.

In th e United Kingdom, the Na tional Radiation Pr o-tection Board has also established some guidelineson electr ic an d ma gnet ic fields for electrical worker s(See table 35).

Table 35. United Kingdom Guidelines on Electric and MagneticField Exposures

Exposures

Occupational:

Cardiac Pacemaker

Electric F ields Magnetic Fields

50Hz

15kV/m

15kV/m

60Hz

15V/m

15kV/m

50Hz

10G

1G

60Hz

10G

1G

However, these gu idelines ar e not officially appr ovedby U.S. Governmen t yet. It is recommen ded tha t a p-propriate protection measures by applied when theworker exper iences discomfort in th e fields.

(4) Personnel protection. The most commonlyused meth od t o protect electrical worker s a gainst elec-tr ic field effects is conductive sh ielding. Form s of shield-ing include condu ctive cloth ing, gloves, insula tion, an dbucket lin ers. Anoth er m eth od of protection is t o avoidunnecessary proximity to electric sources and reducetime of exposure to the electric fields. There is nomethod for magnetic field protection, except distance

from th e field sour ce.

(5) Electric an d m agn etic field exposure gu id e-lines. Ther e ar e no official federa l limits or guidelineson electric and magnetic fields produced by electricpower lines. However, there ar e six states in the UnitedSta tes wh ich h ave set some guidelines on electric andma gnetic fields for electr ical worker s (See ta ble 32).

3-5. Electric shock hazardsElectrical energy cannot be sensed by hum an body un tilconta ct is ma de. Therefore, electrical workers m ust al-ways be awa re of electr ic shock hazar ds. Electr ic shock ha zards can be cau sed by: accidenta lly touching anenergized line or a m eta l object wh ich h as differen tpotent ial from groun d; connectin g two circuits wh ichha ve phase differen ces, or working on an a ppar at us

Table 32. U.S. Guidelines on Electric and Magnetic Field Exposures

Electric Fields Magnetic Fields

States

Florida

Minnesota

Montana

New Jersey

New York

Oregon

On ROW

8kV/m

10kV/m

8kV/m

7kV/m

11.8kV/m

11kV/m

7kV/m

9kV/m

Edge ROW

2kV/m

1kV/m

3kV/m

1.6kV/m

On ROW Edge ROW

150mG(*)

200mG(*)

259mG(*)

200mG(*)

Notes

69-230kV lines

231-500kV lines

500kV 2-lines

Highway

crossing

road crossing

Note: ROW is the right-of-way for which a utility company acquirespermanent rights that allow the utility to build, operate, and maintainits transmission lines, and the right-of-way clear of trees, obstacles, andstructures for the reliability of lines and the safety of electrical workersand the public. (*) Under maximum load carrying conditions.

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Figure 31. Phasing check using hot-line stick and phasing

Figure 32. Phasing check using existing voltage transform

which can have feedback currents. Prejob planningshould be determined before starting work. Prejobplanning includes reviewing the electrical systemdiagrams, inspecting the system and un derstan dingth e system's operat ion. All appar el, tools, an d equip-ment needed for the job should be determined andread y for use.

a . Work ing nea r ene rg i zed c ir cu i t s . Electricalma in tenance pe r fo rmed nea r ene rg ized c i r cu i t sshould be done with pr oper rubber blan kets or othersuitable guards pr ovided as a safety measu re. Safeworking distan ce from t he live appa ra tu s or conduc-tors sh ould also be applied (See para graph 3-9).

b . Poten t i a l d i f f er ences . The potential differ-ences between an energized conductor and ground,or between two energized conductors, are equallyhazardous. The metal frames or enclosures of elec-trical components ma y not be at t he sam e potentialwith the ground. Therefore, they should be consid-

ered as h azar dous. The potential difference betweenconductors (including phase conductors, groundedconductors, and grounding conductors) to groundshould be checked and m easu red. The potentia l dif-ference between metal frames of electrical compo-nents to groun d should also be checked and m easuredbefore sta rt ing a job.

c. Pha se dif ferences. Before connecting two ormore circuits together the phases of the circuitsshould be checked. A short circuit will occur whentwo circuits having different phases are connectedto each other. Only circuit s of sam e pha se can be con-nected. When two circuits ar e in-phase th e voltagesacross th e circuits will be zero. For a power systemless tha n 600 volts a voltm eter can be u sed for phas etesting. For a power system larger than 600 volts ahot stick and h igh voltage voltmet er should be used(See figs 31 an d 32).

d . Feedback cu r ren t s . There is always a possi-bility of a feedback cur ren t wh en working on appa -ratus. A feedback current can result from improperdisconn ection or a ccident al conn ection t o a stored en -ergy power source or electric power source. A thor-ough understanding of the circuitry is necessaryalong with proper disconn ection an d grounding pr o-visions.

3-6. Electrical workWork should be performed on de-energized electri-cal circuits except when continu ous power is requiredfor critical services. In all insta nces, electr ical work-ers should be qualified for the work. Safety proce-dures should be appl ied and personal protect iveequipment should be used. Where work on an ener-

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gized electrical circuit is required the worker mustreceive approval from his/her supervisor and thework mu st be perform ed un der direct super vision of a qu alified foreman .

37. De-energized line workAll lines a re consider ed ener gized un til th ey are com-pletely disconnected a nd isolated from all electr ical

power sources. All stored energy sources such aspower factor capacitors sh all be discha rged to groundthr ough a proper grounding system before sta rt ingth e job. Safety cleara nce should be applied. Barriersand warning signs should be used when it is neces-sar y to prevent access of un au th orized persons to thework ar eas.

38. Safety clearance for de-energized lineworkThis safe ty c learance provides s tandard perfor-ma nces tha t mu st be app lied by all electr ical work-

ers when working on de-energized lines and equip-men t operat ing above and below 600 volts.

a. Definit ions of com m only used electrical terms.The most comm only used electr ical ter ms a re

(1) Switching. The action of shifting, tu rn ing,or chan ging th e existing position or direction of anelectrical interrupting device such as a switch' cir-cuit breaker or recloser to an opposite position ordirection in order to connect, disconnect, or re-con-nect a circuit or electrical device to an electrical powersystem.

(2) B lock in g. Placing a barrier to obstru ct th eoperation of an electrical interrupting device suchas a switch, circuit breaker, or recloser to preventaccidenta l opera tion.

(3) L ock ou t. The application of a locking de-vice to the operating handle of an electrical inter-rupting device such as a switch, circuit breaker, orrecloser to prevent the reposition of the device ex-cept when th e reposition is specifically inten ded.

(4) Tagging. The action of attaching a dan-ger tag or caut ion ta g to an electrical interrupt ingdevice su ch as a switch, circuit br eaker, or r ecloseror to an electrical rotating device such as a motor,generator, or fan or to an electrical tool such as anelectric drill or screw driver.

(5) Personn el protection groun d. A groun dingsystem (including groun ding condu ctors, ground ingelectr odes, an d oth er grounding har dwar e) insta lledan d conn ected int o an electrical power system for the

purpose of discharging electrical energy to groundto protect pers onnel from accident al exposure t o volt-age.

(6 ) C l e a r a n c e ( d a n g e r ) a n d c a u t i o ndetails. The explana tion in deta il of the actions ortasks associated with the application of the dangeror cau tion tags.

(7) M ain H old Ta g. The front side of a DAForm 7408 (Danger Tag) is designated as a "MainHold Tag" when it is attached to a main electricalsystem or equipment to hold its position until thetag is removed by authorized personnel. The MainHold Tag should not be used for any purpose othertha n t he pr otection of personnel un der a safety clear-ance.

(8) Auxi li ar y H old Ta g. The ba ck side of a DAForm 7408 (Dan ger Tag) is u sed as an "Auxiliary HoldTag" when it is used to disable a subsystem or equip-

ment disconnecting devices which may affect thesystem or equipmen t covered by the Ma in Hold Tag.

(9) Caution Tag. A DA Form 5140 CautionTag) used a s a s ta nd-alone or in conjun ction with aDanger Tag. The Caution Tag is attached to a sys-tem or equipment to direct attention of electricalworkers to its abnorm al conditions or unu sua l oper-ating characteristics.

(10) Task. A sta temen t consisting of a sin gleaction verb which indicat es a specific accomp lishm entsu ch a s ''Block S witch A Open", "Lockout Switch A",or "Tag Switch A".

b. Safety clearance duties and responsibil i t ies.The duties and responsibil i t ies of supervisor andworkers en gaged in th e application of a safety clear-ance are as follows.

(1) Supervisor duties and responsibilities. Thesuper visor is responsible for

(a) Designating individual(s) authorized toreceive, request, a pprove, issue, a pply, main ta in, tem-porar y release, and term inate a safety clearan ce.

(b) Supervising an d being responsible for theapplication of safety clearances.

(c) Making all necessary arrangements forinter ru ption of electr ical power ser vice such as noti-fying cust omers an d th e ut ility compa ny.

(d ) Pr oviding direction for th e man agemen t,prepa ra tion, application, and ma inten an ce of safety

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clear an ce records.

(e) Conducting safety clearan ce tra ining andbriefing to ensure a qualified and informed work force.

(2) Worker d uties an d responsibilities. The du-ties a nd responsibilities of workers will vary d epend-

ing upon duty posit ion assignments a s determinedby the su pervisor.

(a) Workers au th orized to approve an d issuesafety clearances must

1. Be technically qualified in all aspects of the electrical system a nd equipment operation andspecifically the paths for current flow and the re-quir ed positioning of th e system cont rol devices suchas d isconnect switches, circuit brea kers, a nd reclosersto de-energize the syst em, or place oth er equipm entinto opera tion when it is necessary;

2 . Receive requests for safety clearances;

3 . Ver ify that the requestor i s author izedto initiate a request and receive a safety clearance;

4 . Review the accuracy of informat ion en-tered on th e Safety Clearance an or Cau tion Orderform relative to the system or equipment involved;

5 . Review the adequacy, sequence, and ef-fectiveness of individual tasks listed on the SafetyCleara nce and or Cau tion Or der form;

6. Provide guidance or correct ion when i tis necessar y;

7 . Make a l l necessa ry a r r angemen t s forpower int err upt ion requ ired for the job;

8 . Not i fy cus tomers and ut il ity companywhen it is necessary (these arrangements must bemade prior to performing any switching which mayaffect t he cust omer's services an d ut ility compa ny'ssystem);

9 . Ensure a complete unders tanding of therequirem ent s for th e cleara nce order on t he Detailof the Clearance Procedures" including the verbalresta ting of th e details of each individual ta sk listedon t he Sa fety Cleara nce Order to the requestor;

10. Determine and ass ign a Safe ty Clear-ance Order nu mber;

11. Annotat e (on th e Safety Clearan ce Or-der form ) the nu mbers of all oth er clear an ce orderswhich a re on the r elated systems or equipment;

12. Fill out the DA Form 7408 (Danger Tag)1 3 . I s s u e t h e D A F o r m 5 1 6 8-R (S a f et y

Cleara nce Order (Electr ical Fa cilities)) and Da ngeror Caut ion Tag to request er;

14. Issue DA Form 7407-R (Caut ion Order(Electrical Facilities)) and DA Form 5140 (CautionTag) in conjun ction with th e Safety Cleara nce Orderwhen requested;

15. Receive, review, and approve requests

for t emporar y lift, release of tem porary lift, an d ter-mination of clearance including the review of thesystems or equipment 's stat us t o determine if oth erworkers will be affected and determine the appro-priate action t o be taken in su ch a case;

16. Mainta in safety clearan ce records in-cluding docum ent ing cleara nce order s an d oth er in-form at ion r elative to issuing an d releasing of clear-

ances and filing of closed-out clearance orders.

(b ) Workers author ized to receive safe tyclearances must

1. Meet the technical knowledge require-men ts specified for the ind ividua l aut horized to ap-prove and issue a clearan ce;

2 . Be technical ly qual ified to perform a l lmeth ods necessary to accomplish th e task s requiredby the "Details of Clearance Procedures" on theSafety Clearan ce Order form;

3. Determine paths of current flow and po-ten tial feed back circuit(s) relat ive to the system or

equipmen t in volved;4 . Dete rmine t a sks or act ions r equ i red to

achieve a cleara nce including a sequen ce of ta sks t ha twill be perform ed t o precede a cleara nce;

5 . P repa re and submi t t he Sa fe ty C lea r-ance and or Caution Order form;

6. Apply safe ty clearance procedures en-suring tha t all tasks ar e performed in the order andsequence as appr oved an d listed on t he Sa fety Clear-an ce an d or Cau tion Order form , annotat ing the timewhen ea ch task is completed;

7 . Conduct a safe ty br iefing for subordi-nat es and coworkers to ensure th at t hey understan dclearly the applied clearance requirements includ-ing familiarizing subordinates and coworkers withthe positioning of all danger tags (main and auxil-iary), caution ta gs, and personn el safety grounds;

8 . Dete rmine the r equ i remen t s for t empo-rary lift of clearances and request temporary lift of cleara nces including coordinat ion an d br iefing otherpersons or crews that may ha ve been working on t heequipment or system;

9 . Reques t au thor iza t ion to r e lease t em-porary lift and reapply the original clearance orderincluding coordina tion an d briefing other persons orcrews tha t m ay ha ve been working on the equipmentor system;

10. Request auth or iza t ion to re lease andperform the release of safety clearances includingperformin g the t ask s of un locking, blocking, tagging,repositioning of switches, an d r emoval of personnelsafety grounds as specified in the details of safetycleara nce procedur es;

11. Prepare tu rn- in an d close-out dan gertags to the issuing authority.

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(c) Workers who receive approved (Clear an ceOrders must

1 . Ap p ly t h e s a fe t y cl ea r a n c e or d e r byimplementing the tasks specified in the ' 'Details of Cleara nce Procedur es";

2 . Pe r form the t a sks in the order and se-quen ce as listed;

3. Fill out th e "Time Applied" for each task

upon completion;4 . Ensure tha t t he r e la t ed power sys t emor equipment is isolated from all power sour ces an dstored ener gy sources and th at t he met hods of block-ing an d locking are pr operly applied;

5 . Apply Danger Tags issued in conjunc-tion with the Sa fety Cleara nce Order;

6 . Sign the "Placed By" column on bothMain a nd Auxiliary Tags.Note: Danger Tags must be applied at the t ime whereth e switching ta sk is perform ed for th e specific dis-connect device identified in "Details of ClearancePr ocedur es. All previous ta gs at ta ched to th e device

mu st be r emoved (by a t emporar y lift order ), exceptwhere other inh erent p roblems preclude th e removalof th e tag.

7 . Conduct a safe ty br iefing, as necessary,to inform subordinates and coworkers on safety is-sues and concerns related to the applied clearance.

(d ) Workers au th orized to request Temporar yLift/ Close-Out of Clearances. Worker who receivesan appr oved safety cleara nce order can request fromth e issuing au th ority a tem porar y lift or close-out of clear an ce. When t his individual is not available, thesupervisor can perform the request or designate aperson to perform this function. The request mustbe appr oved prior to performin g an y task of un lock-ing, blocking, tagging, repositioning of switches orremoval of personnel protective grounds. When acaut ion order is in effect as a r equiremen t of th e clear-an ce order th e following additional pr ocedur es mu stbe perform ed:

1. Request temporary l ift or close-out of thecaut ion simultaneously with t he r equest to tempo-rary lift or close-out of the clearance;

2 . Reques t and app ly a new cau t ion orderfor t he syst em or equ ipment involved. The "Detailsof Caution Procedures" for the new caution ordershould be specified in accordance with the originalCaut ion Order.

(e) Workers a ut horized to appr ove Temporar yLift/Close-Out of Clear an ces. Worker s issuin g safetyclearance orders have authorization to receive andapprove requests for temporary lift or close-out of clearances. However, they must review the systemor equipment sta tus to determine if other workerswill be effected by release of the clearance and-de-

termine th e appropriate action t o be taken in such acase. The worker m ust make all necessary arr ange-ment s for r estorat ion of service such a s notifying th ecustomers and u tility compa ny. These ar ra ngemen tsmust be made prior to performing any switchingwhich may affect the customers' service or utilitycompany's system. They must approve and recordthe temporary lift/close-out of clearance.

WARNING:

(f) Workers who receive approval of Tempo-ra ry Lift/ Closed-Out Or ders mu st

1. Perform th e tasks of unlocking, b lock-ing, tagging, repositioning of switches, a nd removal

of personnel protective groun ds;2 . Pe r form these t a sks in the r eve r se se-

quence as listed on th e Clearan ce Order form;3. Enter the "Time Removed Column" as

each ta sk is completed.Note: The task action to be performed during therelease of a clearan ce is the opposite action as st at edfor a pplying th e clear an ce. For inst an ce, if a t ask of th e clear an ce procedur e read s "Open Switch A" th eopposite opera tion is "Close Switch A".

4 . Remove a l l clea rance t ags ;5 . Submit the c losed-out c learance order

with all associated clear an ce ta gs to th e issuing au-thority.

(g) Workers who receive Turned-In Cleara nceOrders an d Tags must complete the t ermination of clearance by entering the "Released By" and "Ac-cepted By" blocks a nd t he tim e an d dat e the closed-out clearan ce order an d ta gs from t he "active" file toth e "inactive" file.

c. Sa fety cl ea rance forms . Ther e are four sa fetyclear an ce forms: Safety Cleara nce Order, DA Form5168R (fig. 33), Cau tion Or der, DA Form 7408 (fig.35), and Cau tion Tag, DA Form 5140 (fig. 36).

The preparation and application of the forms willdepend on each job.

(1) DA Form 51 68-R (S afet y Cl eara n ce Or der (Electrical Facilities). The Safety Clearance Orderform is used for requesting and issuing a clearancefor electrical work . It contain s all da ta necessary forapplying an d releasing a clearan ce or a temporarylift of clearance. The Safety Clearance Order form

Clearance should not be released whenremoval of the clearan ce will leave otherworkers un protected. In su ch cases, a newclear an ce order mu st be issued, as n eces-sar y, to protect the oth er workers. The n ewclearan ce order mu st be a pplied before theold clearan ce can be released.

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Figure 33. Sample of a completed DA Form 5168-R, Safety Clearance Order(Electrical Facilities).

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Figure 34. Sample of a completed DA Form 7407-R, Caution Order(Electrical Facilities).

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Figure 35. Sample of a completed DA Form 7408, Danger Tag.

Figure 36. Sample of a completed DA Form 5140, Caution Tag.

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must be used for all electrical works performed onde-energized lines and equipment operating above600 volts. DA Form 5168-should be pr epar ed by th eworker who is authorized to receive and apply asafety clearance. The safety clearance order formshould be typed or h an d-written in ' 'black'' or blueink pen or ballpoint pen and filled out as shown infigure 33. DA Form 5168-R will be reproduced on

8 1/2 - by 11-inch p ap er. A copy for rep rodu ction pu r-poses is located at th e back of th is man ua l. The pr epa-ra tion of th e Sa fety Clear an ce Order form follows

(a) Block 1 , Order Num ber. The Order nu m-ber will consist of two sets of nu mbers separ at ed bya h yphen. Th e first set will consist of two digits r ep-resen ting th e curren t year. The second set will con-sist of four digits beginning with th e nu mber "0001".For example: 99-0001.

(b ) B l ock 2 , Ot h er N u m b er. I f t he re a reother cleara nces and or cau tions which ar e in effect

on the system or equipmen t for which th e cleara nceis being requested, the individual who issues thesafety cleara nce will ent er th e order n um bers of th eseclearances/cautions in block 2.

(c) Block 3, S ta t ion/ Ins ta l la t ion . The nameof the station/substation or facility where the sys-tem or equipment is physically located will be en-tered in block 3 by the individual who requests theclearance.

(d ) B l ock 4 , L i n e or E qu i p m en t Involv ed . The description of th e line or equ ipmenton which th e work is to be perform ed will be ent eredin block 4 by the individual who request the clear-ance.

(e) Bl ock 5, Tim e App lied. The individualwho applies the clearance order will enter the timewhen each task is completed. The 24-hour systemwil l be used. Mil i tary (hhmm) or c iv i l ian t ime(hh:mm) ma y be used on a ll forms. For exa mple: 1500or 15:00.

(f ) B l ock 6 , D et a i ls of C l ea r a n ce

Procedure. The deta ils of the ta sks n eeded to com-plete t he cleara nce will be described in block 6. Thetasks m ust be num bered in th e order th at t hey willbe implemented. In t he example substat ion #3 is shutdown and repairs made. Clearance is temporarilylifted midway to test for operation. After the test,unit is shut down again and times recorded in theright ha nd column.

(g ) B lock 7 , Time Removed . The individualwho performs a clearan ce removal will enter the time

when ea ch task is completed. The procedur es to re-move a cleara nce will be in r everse order to tha t u sedfor applying a clearance. The task action used forremoving an order will be the Opposite action t o thatused for inst alling an order. For insta nce, if the ta sk action used to install a clearance order is Openswitch A'', the task action used to remove a clear-an ce ord er is "Close Switch A".

(h ) B lock 8a, I s sued To. The name of theperson who is authorized to receive and implementthe safety clearance will be entered in block 8a bythe issuing authority.

(i ) Block 8b, Issued By. The na me of the per-son who issues th e safety cleara nce must be enter edin block 8b. In cases where the individual issuingand receiving the cleara nce is th e same person t heperson's na me will be enter ed in both th e Issued t o"and "Issued by" blocks.

(j ) B lock 8c, Timed I s sued . The time whenth e safety clear an ce is issued will be ent ered in block 8c by the per son who issues t he clearan ce.

(k ) B lock 8d , Da te I ssued . The date, month,and year when t he clearan ce is issued must be en-tered in this block. Numerical or alphanumericalform s m ay be u sed on a ll forms. For example: 24-12-1999 or 24 Dec 1999.

(l ) Block 9a , Released By. The na me of theperson who releases th e clearan ce must be enteredin block 9a.

(m ) Block 9b, Accepted By. The name of t heperson who accepts the released clearance must beentered in block 9b. In cases where the individualaccepting release and releasing the clearance is theSam e person th e persons na me will be enter ed inboth th e Releas ed By" an d "Accepted By" blocks.

(n) Block 9c, Time Released. The time whenth e cleara nce is released will be enter ed in block 9cby the person who accepts th e released cleara nce.

(o) B l ock 9 d , Da t e R e lea s ed . T h e d a t e ,month, an d year when the clearance is released willbe enter ed in block 9d by th e person who accepts t hereleased clearance.

(2) S afety clearance order logbook. All infor-mation relative to issuing and releasing clearanceorders must be recorded in a logbook. This logbook will also document information on accidents thatoccur du ring a given clearan ce.

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(3) S afety clearance order record fil e. Separatefiles are required for active (still in effect) and inac-tive (released) safety cleara nce orders. I na ctive filesshou ld be ma in ta ined wi th in the o rgan iza t ion ' srecord keeping system according to AR 25-400-2.

(4) S pecial cases. Thr ee special cases exist.

(a ) Operation of the system or equipmentdur ing a cleara nce is not au th orized while the clear-ance is in effect. However, when it is necessary forth e system or equipment or par ts th ereof to be oper-a ted for purposes of opera t ional or af ter-main-tenance, testing, a temporary lift of the clearancecould be applied. There a re no rest rictions on t he tota lnumber of temporary lifts that can be issued rela-tive to a given sa fety clear an ce ord er. However, onlyone temporary lift will be in effect for a given clear-ance at a time. In addition, if the system or equip-ment has multiple safety clearances applied, a tem-porary lift is requir ed for all th e clear an ces in effect.

The issuing authority must coordinate all partiesinvolved to ensu re sa fety of all personnel.

(b) Temporary l ifts of clearance. When m orethan one temporary lift of clearance is needed forthe job each temporary lift should be annotated al-phabetically. The first temporary lift of clearanceshould be given the letter "A". The next temporarylift of cleara nce should be given t he n ext lett er "B",an d so on. The det ailed description for ea ch task per-formed during a temporary lift of clearance shouldbe listed and numbered. The number assigned foreach ta sk per form ed dur ing a lift of cleara nce will bebased on t he nu mber given to a r elated t ask l istedon t he original order but is annotat ed with th e al-phabetical letter of the temporary lift of clearanceas i l lustr ated in figure 33. The t ime when a task isapplied and removed during a lift of clearan ce shouldbe enter ed by th e individual who applied for t he liftof clear an ce.

(c) At an attended su bstation, th e operationsof th e system or equipmen t du ring a lift of clear an ceshould be car ried out by th e opera tor on dut y.

(5) DA Form 74 07-R , (Ca u t ion Or der (E lect ri -cal F acilities)). This form is used to direct electr i-cal workers ' at tent ion t o abnormal, hazardous, andun usu al conditions of an electrical system or device.The caution order differs from the safety clearanceorder in th at t he system equipment may be operatedwhile the cau tion is in effect. The Caut ion Or der isnorma lly used in conjun ction with a clearan ce to ad-dress the conditions of the system or equipmentwhich are not men tioned in the clearan ce order. How-ever, the caution cannot be used in lieu of a clear-

ance. DA Form 7407-R will be reproduced on 8 1/2-by 11-inch p ap er. A copy for r epr oduction pu rposes islocated a t t he back of this ma nua l. The preparat ionof the Caution Order form follows

(a) B lock 1, Ord er N um ber. The Order num -ber will consist of a letter X followed by two sets of nu mbers. Th e first s et of nu mbers will consist of two

digits repr esent ing the curren t year. The second setof nu mber s will cons ist of four digits beginn ing withthe number "0001". For example: X94-0001.

(b ) B l ock 2 , Ot h er N u m b er. I f t he re a reother clearances or cautions which are in effect onth e system or equipment for wh ich t he caut ion orderis being requested, the individual who issued thecaution order will enter the order numbers of thesecleara nces or caut ions in block 2.

(c) Block 3, S ta t ion/ Ins ta l la t ion . The nameof th e sta tion, substa tion, or facility where th e sys-

tem or equipment is physically located will be en-tered in block 3 by the individual who requests thecaution.

(d ) B l ock 4 , L i n e or E qu i p m en t i n -volved. The description of the line or equipment towhich th e caution will be applied, will be ent ered inblock 4 by th e individua l who requests t he caut ion.

(e) B lock 5 , Time Appl ied . The time whena ta sk (listed in the Details of Cau tion Procedur es)is applied an d completed will be enter ed in t his block by the individual who performed the task. The 24-hour s ystem will be used.

(f) Block 6, Details of Caution Procedures.The det ails of caution pr ocedur es will depend uponthe intent of the caution. For a caution order whichinvolves only switchin g, tagging, or blockin g, the de-tail of tasks that need to be performed to completeth e caution should be described in block 6. For a cau-tion order which stipu lates t he operat ion of an elec-trical device or equipment , th e operating inst ructionsmust be entered. Where the instructions have anassigned number t his num ber could be entered. Thedetails of the procedures mu st be n umbered in t hesequential order tha t they will be implemented.

(g) B lock 7 , Time Removed . The pr ocedur esto remove a caution order will be performed in thereverse order to that used for applying the cautionorder. The ta sk action used t o remove an order willbe the opposite to that used for installing an order.For insta nce, if th e task action u sed to inst all a cau-tion order is Open switch A th e ta sk a ction u sed torem ove an order is Close Switch A. The tim e when

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a t ask (to remove an order) is completed will be en-ter ed in block 7 by the individual who perform ed th etask.

(h ) B lock 8a , I ssued To. The na me of th e in-dividual who is authorized to receive and apply acaution order will be entered in block 8a by the issu -ing aut hority.

(i ) B lock 8c, time I s sued . The nam e of theindividual who issues a caution order must be en-ter ed in block 8b. In cases wh ere th e individua l issu-ing and r eceiving th e cau tion order is th e same per-son th e persons na me will be enter ed in both th eIssued To and Issued By blocks.

(j ) Block 8c, Time Issued. The time at whicha cau tion order is issued will be enter ed in block 8cby the person who issues th e order.

(k ) B lock 8d , Da te I ssued . The date, month,

and year when a caut ion order is issued must be en-tered in this block. Both numerical and alphanu-merical form s could be used.

(l ) B lock 9a , Released By. The nam e of theperson wh o releases the caut ion order m ust be en-ter ed in block 9a.

(m ) Block 9b, Accepted By. The na me of th eperson who accepts th e released cau tion order m ustbe enter ed in th is block.

(n ) B lock 9c, Time Released . The t ime a twhich a caut ion order is released will be enter ed inblock 9c by th e individual who accepts th e releasedcaution order.

(o) B l ock 9 d , Da t e R e l ea s ed . T h e d a t e ,month, an d year wher e the caut ion order is releasedwill be entered in block 9d by the person who ac-cepts the r eleased caution order.

(6) Caution order logbook. All informationrelative to issuing an d releasing cau tion orders m ustbe re cord ed on a logbook. This logbook will also docu-ment all operat ions of the system or equipment whileth e caut ion is still in effect.

(7) Caution order record file. Separate filesare required for active (still in effect) and inactive(released) caution orders. Inactive files should bemainta ined within t he organization's record keep-ing syst em a ccording t o AR 25-400-2.

(8) Special applications. Caution orders re-ma ining in effect for an ext ended per iod mu st be re-

viewed annu ally at a m inimum to determine if therequirement still exists. Results of the review mustbe communicated to all elements of the operation.Caution orders issued for abnormal/unusual condi-tions of an electrical system or equipmen t wh ich can -not be corr ected will become a pa rt of th e equipmen t'sperma nen t record an d may rema in indefinitely. Cau-tion orders issued for abnormal/unusual condition

of mobile equipment must be transferred from thelosing issuing authority to the gaining issuing au-thority when th e equipment is tra nsferred betweenauthorities. In this case a duplicate of the order isprepared a nd forwarded t o the gaining, issuing au-thority and the caution tag is left attached to theap plicable device.

(9 ) DA Form 7408 (D an ger Tag) (f ig. 35 ) .Danger Tags must be used in conjunction with theDA Form 5168-R (Safety Clearan ce Order), an d mu stbe applied with each safety clearan ce issued. The ta gmust never be used for an y purpose other tha n t he

protection of personnel working u nder a safety clear-ance order. A tag is applied to systems and equip-ment to ensure that a device's position will not bechan ged by unaut horized persons a s long as the sys-tem or equipment has an active safety clearance ineffect. The ta g can only be removed by the in dividua lwho insta lls th e tag or a n a uth orized person desig-na ted by his/her super visor.

(a ) M ain H old Ta g. The front side of theDanger Tag is designated as the Main Hold Tag.The Main Hold Tag is used to attach to a primarydisconnecting device of a circuit to ensure that theposition of th e device will not be chan ged by un au -thorized persons as long as the tag is attached. AMain Hold Tag will be applied for each sa fety clear-ance issued and remain a tta ched for as long as th esafety clearance order is in effect.

(b ) P rep a ra t ion o f M a in H o ld Ta g. Th eMain Hold Tag will be prepared by the individualwho issues the tag. It will contain data consistentwith th at l isted on th e associated Safety Clearan ceOrder, such as substa t ion name, c learance ordernu mber, line or equipment involved, issuing a ut hor-ity, applying aut hority, dat e an d time applied. Wherean Auxiliary Hold Tag is used in conjun ction with aMain Hold Tag, the location (or placement) of theAuxiliary H old Tag will be listed on t he Main HoldTag. The n am e of th e worker wh o inst alls th e Auxil-iary H old Tag will also be ent ered. The n am e of th estation/substation or facil i ty where the system orequipment is physically located will be entered inth is block by the individual who request s th e clear-ance. The clearan ce num ber must be entered in th isblock by th e individua l who issues t he Dan ger Main

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Hold Tag, as given on the Safety Clearance Orderform . The ta g num ber will be one (1) when th e ta g isused a s th e Main Hold Tag. The ta g num ber will beentered by the individual who issues the tag. Thedescription of the line or equipment on which thework is to be perform ed will be enter ed in t he Clear-an ce On block by the ind ividua l who issues th e Dan -ger Main H old Tag. The n am e of th e individua l who

receives the Danger Tag will be entered in the Is-sued To block by th e issuing a ut hority. The na me of the ind ividua l who issues t he Dan ger/Main H old Tagmust be entered in the Issued By block. In caseswhere th e individual issuing an d receiving the Dan-ger/Main H old Tag is th e sam e person, the per son'sna me will be enter ed in both th e Issued To an d Is-sued By blocks. The date, month, and year whenthe Main Hold Tag is installed must be entered inthe Date block by the individual who installs thetag. Both nu merical and alph an umer ical forms couldbe used. For example: 24-12-1999 or 24 Dec 1999.The time when the Main Hold Tag is installed will

be ent ered in th e Time block by the in dividua l whoinstalls the card. The 24-hour system will be used.B o t h m i l i t a r y f o r m ( h h m m ) a n d c i v i l i a n f o r m(hh:mm) could be used. For example: 1500 or 15:00.The name of the individual who installs the Auxil-iary H old Tag will be ent ered in t he Placed By (Aux-iliary Tag Placemen t Section) block by th e individua lwho received th e ta g. The locat ion wher e th e Auxil-iary H old Tag is to be placed, as specified in t he Sa fetyClearance Order, will be entered in the Location(Auxiliar y Tag P lacemen t Section) block by the issu -ing authority. The name of the individual who re-moves the Auxiliary Hold Tag will be entered in th eRemoved By (Auxiliary Tag Placement Section)block by the in dividua l who receives th e ta g.

(c) Aux il ia ry Hold Tag. The ba ck side of theDan ger Tag is designat ed as th e Auxiliary H old Tag.The Auxiliary Hold Tag is used t o atta ch to subsystemdisconnecting devices t o disable su bsystem circuitswhich may affect the system or equipment that isbeing worked on.

(d) Prepara t ion of Auxi liary Hold Tag . Th eAuxiliary H old Tag will be prepar ed by the individua lwho issues the tag. It will contain data consistentwith th at listed on th e Main Hold Tag such as clear-ance order number, line/equipment involved, issu-ing auth ority and so on. The clearan ce num ber mu stbe entered by th e individua l who issues th e tag. Thisnumber was given on the Safety Clearance Orderform. The tag num ber entered must m atch with theassigned n umber listed on t he Tag Nu mber colum nof th e Main Hold Tag, where t he locat ion of th e Aux-iliar y Hold Tag ma tches with th e location d escribedon the Ma in Hold Tag. The sam e nu mber will also be

entered on the Tag No block on the other side of the tag. No other information is necessary on theother side of the tag when the t ag is used as an Aux-iliar y Hold Tag. The n am e of th e individual who in-sta lls the Auxiliar y Hold Tag will be enter ed in th ePla ced By block by th e individu al wh o receives th etag. This na me should also be entered on t he MainHold Tag. The t imes when th e Auxiliar y Hold Tag is

insta lled will be entered by t he ind ividual wh o placesth e tag. The na me of th e individua l who receives theAuxiliary H old Tag will be ent ered in th e Issu ed Toblock by the issuing authority. The location whereth e Main H old Tag is insta lled sh ould be filled in byth e issuing a ut hority. The description of th e line orequipment held by the Auxiliary Hold Tag must befilled in by t he issu ing au th ority. The locat ion wh ereth e ground r od is insta lled for t his clear an ce shouldbe enter ed by the issuing au th ority. This groun d lo-cation must be filled in conjunction with the MainHold Tag.

(e) D a n ger Ta g H ol d er. The Danger Tagmust be placed inside a tag holder to prevent da magecaused by weat her or destru ctive operation of th e elec-trical equipment or devices. Tag holders must be of anonconductive, see-through (that is clear plastic) ma-terial designed for ins tallation with a switch st ick.

(f ) S p eci a l a p p li ca t i on s a r e as f ol l ow s :Gan g-operated switches m ust be locked open a nd a nappropriate number of danger tags (one for eachsafety clear an ce) must be applied to th e lock. Like-wise, a turbine throttle valve must be locked in theclosed position a nd ta gged. For overh ead lines, a vis-ible line-brea k m ust be provided at a ll points of pos-sible feed. An open oil circuit breaker is not accept-able. When an oil circuit breaker must be used, theline-side leads must be removed from the breakerbushings and the breaker must be mechanical lyblocked open, locked-out, an d t agged. In addition, avoltage test will be used t o deter mine th at t he linesar e de-energized. Protective groun ds will be insta lledon the lines as close as possible to the oil circuitbreaker.

WARNING:

Per form t he voltage test t o verify tha t th e

circuit is de-energized before install ingprotective ground or serious injury mayoccur. For un dergroun d system s, a visibleline-bra ke mu st be provided when feasible.When an oil circuit break er or oil-discon-nect switch must be used, the same re-quirem ents as s pecified for overhea d linesmust be met . Oi l fuse cutouts must beblocked and locked in the open position.The fuse block must be removed and theclamp mu st be dan ger tagged.

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(10) DA For m 51 40 (Ca u t ion Ta g). (Fig . 36 ) .Cau tion Tags ar e normally used to atta ch to an elec-tr ical system or equipment to direct a tten tion of elec-trical workers t o the abnormal, hazardous, and u n-usual operating conditions of the system or equip-ment or device. The caution differs from the clear-ance in that the system or equipment ma y be oper-at ed while the caut ion is in effect. The cau tion can -

not be u sed in lieu of a cleara nce.

(a) Preparation of Caution Tag. The front sideof th e tag should be prepar ed by th e individual whoissues the tag. The back side of the tag should besigned by th e individual who operat es th e equipment.On side A the Caution Order number must be en-ter ed in th is block by the individua l who issues t heta g. This nu mber is given on t he Cau tion Order form.The name of the station, substation, or facility atwhich the effected equipment or electrical device isphysically located will be ent ered by th e issuing au -thority. The description of the l ine or equipment

to which t he caut ion t ag will be att ached will be en-ter ed by th e issuing aut hority. The abnorma l condi-t ions and unusual operating characterist ics of thesystem or equipment m ust be entered in this block by the issuin g aut hority. Special instr uctions n eededto operate an electrical system or run equipment ora device should be entered in th is block by the indi-vidual who issues the tag . The t ime in minutesneed ed to wa it before closing or reclosing a circuit oroperate electrical equipment should be entered bythe issuing aut hority. The n ame of the individual whorequest s the caut ion order will be entered by the is-suing a ut hority. The nam e of the individua l who ap-proves the caut ion order will be entered by th e issu-ing authority. The name of the individual who in-sta lls the t ag will be entered in th e "Placed By" block by the individual who receives the ta g. The nam e of the individual who releases the tag will be enteredby the individual who receives the released t ag. Thena me of th e individua l who au th orizes the r elease of th e ta g will be ent ered in th e "Ordered Off By" block.Norma lly, the issuing au th ority approves the r eleaseof th e ta g. The nam e of th e individual who removesth e tag will be enter ed by the issuing au th ority. Onside B, th e nam e of th e individua l who operates t hesystem or equipmen t while the cau tion tag is still ineffect mu st ent er his/her n ame. The t ime when thesystem or equipment is operated while the cautionis still in effect will be ent ered by t he opera tor. Thedat e, month, an d year when t he system or equipmentis operated while th e caut ion is still in effect will beentered by the operator.

(b ) C au t i on Ta g H ol d er. The Cau t ion Tagmust be placed inside a ta g holder to prevent da m-age caused by weather or destructive operation of

th e electr ical equipmen t or device. Tag h olders m ustbe of a n oncondu ctive, see th rough (th at is, clear pla s-tic) ma ter ial designed for inst allation with a switchstick.

(c) Specia l appl ica t ions . Cau tion Tags whichrema in in effect for an exten ded period, must be in-spected monthly as a minimum to determine that

th e tags ar e physically atta ched, an d protected frominclement weather.

d. Safe ty Clearance/ Caut ion Order processing.The Safety Clearance/Caution Order processing isas follows:

(1 ) T h e in d i vi d u a l a u t h o r iz ed t o r e ce iv e aSafety Clearance/Caution Order must prepare theSafety Clearan ce Order, DA Form 5168-R, and or th eCaution Order, DA Form 7407, and submit the re-quested order(s) to the individua l who ha s au th orityto issue the order(s). The requester must provide a

detailed description of all tasks which are requiredfor th e system or equipment isolation an d personnelprotection.

(2) The individual author ized to issue a Safe tyCleara nce/Cau tion Order will

(a) Receive the request for Safety Clearance/ Caution Order.

(b ) Rev iew the sys t em o r equ ipmen t s t a tusto determ ine if oth er worker s will be affected by t herequested/Clearance/Caution Order, and determinethe a ppropriate a ction t o take in such a case.

(c) M a k e a l l n e ce s sa r y a r r a n g e m en t s forscheduled outages, such as notifying the customersand utility company, if necessary.

(d) Issue the Safe ty Clearance/Caut ion Or-ders a nd Da nger/Caut ion Tags necessary for t he job.

(e) Record and follow up the all clearancesin effect.

(3) The individual who received the a pprovedSafety Clearance/Caution Order, has authorizationto request a tem porary lift of clear an ce. He/she mu stprepar e and submit t o the issuing aut hority a supple-ment al Sa fety Cleara nce Order, DA Form 5168-R.

(4) The individual who receives the request fortemp orary lift of clear an ce will review th e system orequipment sta tu s to determ ine if other workers willbe affected by t he lift of cleara nce an d deter mine t heappropriate action t o take in su ch a case.

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(5) The individual who received the approvedtempora ry lift must per form a ll ta sks as outlined inthe supplemental Sa fety Cleara nce Order form.

(6) The issuing author ity wi ll have author iza-tion to approve the release of temporary l if t andSafety Clearance or Caution Order. No release of safety cleara nce/caution can be performed before t he

release was approved.

(7 ) T h e i n d iv id u a l a u t h o r iz ed t o r e l ea s e aSafety Clearance/Caution must complete all taskslisted on the approved order, but in reverse orderand opposite sequence from t hat in which the t asksare appl ied . For ins tance , i f a task reads "OpenSwitch A" when a clear an ce is a pplied, the oppositeopera tion is "Close Switch A".

3-9. General rules for de-energized line workThe following rules should be applied for all de-en-ergized line work.

a. Low voltage de-energized l ine work (600 Voltsand below). All de-ener gized lines/equipment /appa-ratus to be worked on should be securely groundedto a comm on groundin g electr ode. An equipotent ialvoltage between the line/equipment /appar at us to beworked on and the platform on which the workerstands must be checked before start ing work. Anap proved voltm eter, scope met er, or voltage det ectormus t be used for th is test. All au tomat ic devices suchas au tomat ic tr an sfer switches should be physicallytu rn ed off or d isconn ected if it is possible. All stor edenergy sources such a s power factor capacitors sh ouldbe properly drained to ground. The grounding con-ductor used to drain t he stored ener gy should be re-tained until the work is completed. In cases wheret h e l i n e s / e q u i p m e n t / a p p a r a t u s s h o u l d n o t b egrounded the foreman must explain to his/her crewthe reasons for not grounding. All other energizedlines, equipment, or apparatus which are not con-nected to the system t o be worked on, but a re with inthe reaches of electrical worker, should be coveredwith insulated protective equipment. Always treatbare wires such a s ground wires of unint errupt iblepower systems or communication systems, as ener-

gized lines.

b . Med ium and h igh vol t age de-energi zed l i nework (above 600 volts). The following rules mustbe applied before star ting a ny line work:

(1 ) Clea r ly unde r s t and the in s t ruct ions andwork requirements.

(2) Prepare a l l necessary tools and equipment .

(3 ) Prepa re sa fe ty p rocedures.

(4) Apply personal protect ive equipment .

(5) Perform a safety clearance for l ines/equip-ment/appara tus to be worked on.Note: When inst alling a temporar y groun d for a line,equipment, or appar atu s th e connection to ground

must be made first. Before making a connection toan electric line/equipment/apparatus, test for staticdischarge with a switch stick as an added precau-tion. When removing a temporary ground, discon-nect th e groun d conn ection last.

(6) Cover all other energized l ines/equipmentwithin reach with insu lated equipment such as rub-ber line hose, insula tor hoods, or ru bber blanket s.

(7) Discharge a ll surge arres ters and s tored en-ergy devices, if exist ing.

(8 ) Guard the work ing a rea with su i t able ba r-riers an d warn ing signs from access by unau th orizedpersons.

(9) Before s tar t ing work, check th e equipoten-tial voltage between the l ine/equipment/appar atu sto be worked on a nd t he platform where th e workerwill stand.

(10) Before cutting a cable, be sure tha t th e cablehas been correctly identified by your foreman bychecking the duct and cable location against thatshown on working print or by cable identificationtags. The working print must also be checked againstth e facility engineer's m ap r ecords. Cables can alsobe identified with the aid of an exploring coil by lis-ten ing for a pulsa ting beat imposed on t he cables bysending an interru pter signal.

(11) After t he cable has been ident i f ied andgrounded, remove a three inch strip of coveringaround cable and test with a voltage detector at twoor more points n ear t he center of th e exposed insula -tion. Repeat t he test with an other volta ge detector if it is ava ilable. Alter na tively, a sp iker can be used, a sdescribed in para graph 75.

(12) When cutting cable, place a h acksaw on t heexposed cable insulation adjacent to and touchingth e groun ded meta llic shield or shea th or th e tempo-rar y ground on t he shield or sh eath before cutting.

(13) Do not a pproach or touch reactors a nd con-nected equipment un less it has been proven tha t th eyare de-energized and grounded.

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(14) When the worker changes posit ion he/shemust check all energized lines within his/her reachagain a nd r e-cover them with insulated equipmentwhen it is necessary before starting the new work.

310. Permanent and temporary groundA permanent ground is installed for safe operationof electr ical power systems an d devices. A temp orary

ground is used for electrical worker's safety whenengaged in electr ical services.

a . P u rp os e of gr ou n d i n g. The purpose of agrounding is to limit the p otential differences resu lt-ing from fault conditions to values th at ar e safe whentouched by a h uma n body. This assures th at a per-son in th e vicinity of working ar ea is n ot exposed tothe danger of critical electric shocks.

b. Def in i tion of grounding terms.

(1 ) G r o u n d : A c o n d u c t i n g c o n n e c t i o n ,whether intentional or accidental, between an elec-trical circuit or equipment and the ea rth or to somecondu cting body tha t serves in place of th e eart h.

(2) Grounded: Connected to earth or to somecondu cting body tha t serves in place of th e eart h.

(3) E ffect ively grou n d ed : Int entionally con-nected to eart h t hr ough a ground connection or con-nections of sufficiently low impedance and havingsufficient current-carrying capacity to prevent thebuildup of voltages that may result in undue haz-ar ds to connected equipment or to persons.

(4) Groun ded cond uctor: A system or circuitconductor that is intentionally grounded.

(5) Ground ing cond uctor: A conductor u sed toconn ect equipment or the gr ounded circuit of a wir-ing system to a gr ounding electrode or electrodes.

(6) Equ ip m ent ground in g conductor : The con-ductor u sed to connect th e noncurrent -carr ying met alparts of equipment, raceways, and other enclosuresto the system grounded conductor, the grounding

electr ode cond uctor, or both a t th e service equipm entor at t he source of a sepa ra tely derived system.

(7) Grounding electrode conductor: The con-ductor used t o connect the gr ounding electrode to th eequipmen t groun ding conductor, to the groun ded con-ductor, or t o both of th e circuits a t t he ser vice equip-ment or at the source of a separately derived sys-tem.

(8) Ground-fault circuit-interrupter: A device

intended for the protection of personnel that func-tions to de-energize a circuit or port ion t her eof withinan es tabl ished per iod of t ime when a current toground exceeds some predet erm ined value tha t is lessthan that required to operate the overcurrent pro-tective device of the supply circuit.

(9 ) Ground-fault protection of equipment:

A system inten ded to provide protection of equipmen tfrom da ma ging line-to-ground fau lt curr ent s by op-erating to cause a disconnecting means to open allungrounded conductors of the faulted circuit. Thisprotection is provided at current levels less thanthose required to protect conductors from damageth rough th e opera tion of a supply circuit overcur rentdevice.

(10) R ef eren ce gr ou n d . A conducting bodysuch as th e earth and t he meta l fram e of a buildingto which an electr ic potentia l is referenced.

c. Types of ground ing. Five types of groun dingwill be described in th e section: power system ground-ing, equipment grounding, electrostatic grounding,l igh tn ing p ro tec t ion g round ing , and t empora rygrounding.

(1) Power system grounding. Power systemgrounding h as t hree m ain functions:

(a) Sta bilize the system voltage to ground.

(b) Limit th e overvoltages produ ced by light-ning stokes, line sur ges, or un inten tional cont act withhigher voltage lines.

(c) Facili tate the operation of overcurrentprotective devices such as fuses, circuit breakers,reclosers, an d relays u nder ground-fau lt conditions.

(2) Equ ip m en t grou nd in g. The ma in functionof equipment grounding is to provide a low imped-an ce pat h for fault current s to flow back to th e sourceto activate the operation of overcurrent protectivedevices u nder ground-fau lt conditions.

(3) E lect rosta tic groundin g. The generat ion of static electricity is not a hazard in itself. However,the h azard a rises when an accumu lated stat ic elec-tric charge is subsequently discharged as a spark.Occupa ncies wher e flamm able or explosive liquids,gases, dusts, or fibers are present need an electro-static grounding to reduce sparking.

(4) L igh tn in g prot ection grou nd in g. The esti-ma ted energy dissipated by a direct light ning str okeis approximately 300,000,000 Joules or equivalent

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Table 36. Recommended Grounding Cable Sizes

Cable Sizesin Copper (AWG)

2/0

3/0

4/0

Fault time(cycles)

Maximum FaultCurrents in Amperes

1530

1530

1530

27,000 or less20,000

36,00025,000

43,00030,000

to l0,000,000,000 kWatts or 66 kG of TNT. The Na-tional Electrical Code (NEC) requires a separategrounding system be used for lightning protection.Power system grounding can not be used as light ningprotection gr ounding.

(5) Tem porary groun din g. Temporar y groun d-ing is used for personal safety. A de-energized line

located ad jacent to an en ergized line is always sub- ject t o bot h ca pacit ive an d magn et ic cou plin g fromth e live line which can indu ce volta ge in th e de-en-ergized lines. In addition, accidental energizing of th e lines, accumula tion of sta tic cha rges on th e line,improper dra in of power capa citors, or su rge arr est-ers a re other ha zards for electrical workers. Tempo-rary grounding shall be applied to all lines, equip-ment, or apparat us to be worked on an d remain un -til th e work is completed.

(a ) I n st al la ti on . Before insta lling a temp o-rary ground, the l ine/equipment /device must be

tested for differential voltage. Pr oper clear an ce dis-ta nce and h ot-line tools must be applied even wh enth e line/equipment /device is de-ener gized. Tempora rygrounding sha ll be insta lled at both en ds of th e line/ equipment /appa ra tu s to be worked on when it is nec-essary. All conducting objects such as static lines,tra nsformer tan ks, and platforms wh ere the electri-cal workers stand shall be connected together toground to prevent dan gerous touch an d step voltage.

(b ) G rou n d i n g con d u c tor s. Te m p o r a r ygrounding condu ctors sha ll be of copper, ru bber in-sulat ed, an d flexible type. Aluminu m gr ounding con-ductor is not perm itted. Since the r esistance of a con-duc to r i s p ropor t iona l t o i t s l eng th , t empora rygrounding conductors shall be kept as short as pos-sible. In gener al, grounding condu ctor length shouldbe limited to 30 feet. Sharp bending of groundingcond uctors sh ould be avoided. The size of groun dingconductors will depend on the maximum fault cur-rent s a vailable at th e service locat ion. Table 3-6 pr o-vides recomm ended sizes for ground ing condu ctors.Where two or more grounding conductors are usedthe ma ximum fault curren ts l isted in t his table canbe dera ted by a factor of 0.9. Temporar y groundingconductors should have the same length if they areconn ected at both en ds of a line, piece of equipmen t,or appara tus .

(c) Ground ing el ect rodes . The temporarygrounding electr ode should be driven a t least 6 feetinto ground. Where a perm anen t grounding electrodeexists, it can be used inst ead of a tem porar y groun d-ing electrode. However, the permanent groundingelectrode should be checked for good condition be-fore use.

d . Wha t needs to be grounded . All metal elec-tr ical component enclosur es, maint ena nce vehicles,equipment, or devices located within or near work-ing areas shall be properly grounded to a commongrounding point.

(1) Elect ri cal com pon ent en closures . All meta lenclosures for electrical components such as trans-form ers, circuit br eaker s, switches, switchgear, and

reclosers located within or near working area s mustbe properly grounded to a comm on grounding elec-trode (either temporary or perman ent), through ap-proved grounding conductors.

(2) De-en ergi zed elect ri cal com pon ents. All de-energized electrical components such as overheadlines, power transformers, and capacitors shall beproperly grounded t o a common grounding electrode(either tem porar y or perman ent), through a pprovedgrounding conductors. The grounding conductorssha ll remain u nt il the electr ical work is completed.

(3) Aer ia l el ect ri ca l gr ou n d in g com pon en t s.All aerial electrical grounding components such aslight ning ar rest er ground ing wires, metal pole, pole-mounted transformers grounding wires, and staticwires located n ear or within working ar eas mu st beproperly grounded t o a common grounding electrode(either temporary or perm anent ) through appr ovedgrounding condu ctors.

(4) Mai n tenan ce veh icl es. When maintenan cevehicles such as a utility trucks or boom trucks areparked within minimum approach distances listedin t able 3-8. The vehicles' chassis mu st a lso be prop-erly grounded to the common grounding electrode(either t emporar y or perm an ent ) for th e service areath rough an appr oved grounding condu ctor.

(5) Platform or boom wh ere the worker stand sshould be bonded to the l ines/ equipm ent/ devices tobe worked on. An equipotential between t he plat-form or boom where the worker sta nds a nd t he l ine/ equipmen t/device to be work ed on mu st be checkedby an appr oved instr um ent before sta rt ing work. All

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