subpart s electrical h:\extprg\pp\subpts.ppt. subpart s electrical standards

$: Subpart S Electrical h:\extprg\pp\subpts.ppt. Subpart S Electrical Standards$
Subpart SElectrical

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Subpart S

Electrical Standards

1910.301Introduction

(a) Design Safety Standards for Electrical Systems– 1910.302-308– 1910.309-330 (future design)

Safety-Related Work Practices– 1910.331-360

(c) Safety-Related Maintenance Requirements– 1910.361-380

Safety Requirements for Special Equipment– 1910.381-399

(e) Definitions - 1910.399National Safety Educational Center 1-800-656-5317

1910.302 - ElectricUtilization Systems

National Safety Educational Center 1-800-656-5317

Industrial substations Conductors connecting

supply of electricity Other outside conductors

on premises

Yards Carnivals Parking/Other lots Mobile homes Recreational vehicles

(a) Scope–(1) Coverage–Equipment installations used within or on buildings,

structures, and other premises, including:

1910.302 - ElectricUtilization System (Cont)

Ship installations Watercraft Railroad rolling stock Aircraft Automotive vehicles

other than RV’s

Railroad generating, transforming, transmitting or distribution of power

Communication equipment

Electric utilities

(a)(2) Not Covered:


1910.302 - ElectricUtilization Systems (Cont)

— 1910.303(b)-(f)— 1910.303(g)(2)— 1910.304(e)(1)(i)— 1910.304(e)(1)(iv)-(v)— 1910.304(f)(1)(ii)-(v)

— 1910.304(f)(3)-(4)— 1910.304(f)(5)(iv)(a)-(d)— 1910.304(f)(5)(v)-(vi)— 1910.304(f)(6)(i)— 1910.305(g)(1)(i)-(iii)— 1910.305(g)(2)(ii)-(iii)

(b) Extent of application(1) Requirements apply to all electrical installations(regardless of when designed and installed) in sections:


1910.302 - ElectricUtilization Systems (Cont)

(b)(2) Every system/equipment installed after March 15, 1972, and major replacements, modifications, repairs, or rehabilitation after March 15, 1972 of older systems, shall comply with 1910.302-308.


1910.303General Requirements

(a) Only approved conductors and equipment (b) Examination, installation and use of equipment

– (1) Electrical equipment free from recognized hazards likely to cause death/serious physical harm to employees [5(a)(1)]

– (2) Installation and use - listed or labeled equipment shall be used or installed in accordance with any instructions included in the listing or labeling


1910.303 - GeneralRequirements (Cont)

(c) Splicing

– Conductors joined or spliced by» Brazing» Welding» Soldering

– Covered by insulation (d) Arcing parts shall be enclosed


1910.303 - General Requirements (Cont)

(e) Marking - Electrical equipment shall be marked:– Manufacture’s name– Trademark– Voltage– Current– Wattage– Durable markings



(f) Identification of disconnecting means and circuits for the following shall be legibly marked and durable:– Motors– Appliances– Each service– Each feeder– Each branch circuit


1910.303 - GeneralRequirements (

(g) 600V or less– (1)(i) Working space about electrical equipment (Table S-1)– (ii) Clear spaces: working space/no storage– (2) Guarding of live parts

» 50V or more guarded against accidental contact by:• Approved cabinets/enclosures• Location in room/vault• Partitions/screens (only qualified persons)• Location on balcony, gallery, platform• Elevation: 8 ft. or more above floor



(h) Over 600V

– (3) Workspace about equipment

»See Table S-2


1910.304 - Wiring Designand Protection

(a) Use/identification of grounded/grounding conductors– (1) Distinguishable from other conductors (Usually

green)– (2) Polarity of connections

» No reverse polarity on leads/terminals– (b) Branch circuits

» (1) Reserved» (2) Outlet devices

• Ampere rating not < load served


1910.304 - Wiring Designand Protection (Cont)

(c) Outside conductors - 600V or <– (1) Conductors on poles - horizontal climbing space not less than:

» (i) Power conductors below communication conductors - 30”» (ii) Power conductors alone or above communication conductors -

300V or less - 24” > 300V - 30”

» (iii) Communication conductors below power conductors* 300V or less - 24”* 300V or more - 30”



(c)(2) Minimum clearances from ground:

– (i) 10 ft. - above finished grade, sidewalks, platforms

– (ii) 12 ft. - over areas subject to vehicle traffic (not truck traffic)

– (iii) 15 ft. - over areas subject to truck traffic

– (iv) 18 ft. - over public streets, alleys, roads, driveways (3) Clearance from building openings - conductors shall have clearance of at

least 3 ft. from windows, porches, doors, and fire escapes



(c)(4) Clearance over roofs

– Conductors shall have clearance of at least 8 ft. from highest point of roofs over which they pass

– Exceptions:

– (i) Voltage between conductors

» 300V or < and roof slope 4” in 12--clearance from roofs 3 ft.; or,

– (ii) Voltage between conductors

» 300V or < and conductors do not pass over more than 4 ft. of overhang portion of roof--clearance from roofs 18”



(d) Services

– (1) Disconnecting means

» (i) GeneralShall be provided to disconnect conductors (in buildings

or structures) from service entrance conductors Indicators for open and closed positionsReadily accessible location nearest point of entrance of

the service-entrance conductors


1910.304 - Wiring Designand Protection (Cont’d)

(d)(2) Services > 600V

– (i) Guarding -- Service entrance conductors installed as open wires accessible only to qualified persons

– (ii) Warning signs -- High voltage signs for other than qualified employees



(e) Overcurrent protection

– (1) Circuits 600V or <

» (i) Protection of conductors and equipment from overcurrent

» (ii) Grounded conductors

* Except for motor running overload protection, no interruption of grounded conductors, unless all circuit conductors opened simultaneously

* (iii) Disconnection of fuses and thermal cutouts

* Except service fuses, all fuses, thermal cutouts, circuits > 150V to ground


1910.304 - Wiringand Protection (Cont)

(e)(1)(iv) Location in or on premises – Overcurrent devices readily building management

personnel (v) Arcing/Suddenly moving parts

– Fuses/circuit breakers located or shielded so not to cause burns or injuries

(vi) Circuit breakers shall indicate– Open (Off)– Closed (On)



(f) Grounding– (1) Systems to be grounded

» (i) All 3 wire DC systems - neutral conductor grounded

» (ii) 2 wire DC systems over 50V to 300V between conductors - grounded

– (2) Conductors to be grounded» AC systems - identified



(f)(3) Grounding connections (4) Grounding path

– Path to ground from circuits, equipment, enclosures - permanent and continuous


1910.304 - Wiring Designand Protection (Con)

(f)(5) Supports, enclosures and equipment to be grounded– (i) Metal cable trays, metal raceways, metal conductor

enclosures shall be grounded– (v) Equipment connected by cord and plug

» Non-current carrying metal parts of cord and plug connected equipment which may be energized shall be grounded IF:

in hazardous locationsoperated at > 150Vof types such as: refrigerators, A.C., hand-held motor tools,

tools used in wet locations, portable hand lamps


1910.305 - Wiring Methods,Components and Equipment

(a) Wiring methods– (1) General requirements

» (i) Metal raceways, cable armor, and other metal enclosures shall be metallically joined together into continuous electric conductor and be connected to all boxes, fittings, cabinets for effective electrical continuity


1910.305 - WiringMethods, etc. (Cont)

(a)(2) Temporary wiring– (i) Uses permitted - 600V or <

» (A) Remodeling, maintenance, repair, demolition

» (B) Experimental or development work» (C) Period not > 90 days for Christmas

lighting, etc.



(b)(1) Conductors entering cabinets, boxes, fittings– Protected from abrasion– Openings effectively closed

(2) Covers and canopies– Pull boxes, junction boxes, fittings provided

with approved covers



(c) Switches– (1) Knife - Single-throw type

» Blades dead - switch open position» Placed so gravity will not tend to close switch

– (2) Faceplates for flush-mounted snap switches



(d) Switchboards and panel boards– Live parts located in dry locations– Accessible to qualified persons– Panel boards shall be mounted in cabinets,

cutout boxes or enclosures and dead front



(e) Enclosures for damp or wet locations– (1) Cabinets, cutout boxes, fittings, boxes, panel board enclosures

installed to prevent moisture in enclosures– Wet locations - weatherproof enclosures– (2) Weatherproof enclosures for

» Switches, circuit breakers, switchboards in wet locations (f) Conductors for general wiring shall be:

– Insulated– Approved for voltage, operating temperature, location of use– Distinguishable by appropriate color or other suitable means



(g) Flexible cords and cables

– (1) Approved usage

» Pendants

» Wiring of fixtures

» Connection of portable lamps and appliances

» Elevator cables

» Wiring of cranes and hoists

» Connection of stationary equipment to facilitate interchange



(g)(1)(iii) Flexible cords may not be used

– As a substitute for fixed wiring

– Where run through holes in walls, ceilings, floors

– Where run through doorways, windows, openings

– Attached to building surfaces

– Concealed behind walls, ceilings, floors



(g)(2) Identification, splices and terminations

– (i) Conductors - Flexible cords and cables used as grounded conductor or equipment grounding conductor shall be distinguishable.

– Types SJ, SJO, SJT, SJTO, S, SO, ST, and STO shall be durable marked with:

» Type designation

» Size

» Number of conductors



(g)(2)(ii) Flexible cords– Used only in continuous lengths (no splicing/taping)– Hard surface #12 or larger may be repaired, if splicing retains

insulation and sheath properties (iii) Flexible cords - connected to devices and fittings to provide

strain relief (j) Equipment for general use

– (1)(i) Lighting fixtures, lampholders, lamps, receptacles and rosettes

» No live parts exposed unless 8 ft. above


1910.306 - Specific PurposeEquipment and Installations

(a) Electric signs and outline lighting – (1) Disconnecting means

(electronic/electromechanical controllers) -» Capable of being locked in open position


1910.306 - Specific PurposeEquipment (Cont)

(b) Cranes/Hoists


» Between runway contact conductors and power supply

» Another means, capable of being locked in open position, shall be provided

– (2) Control

» Limit switch to prevent load block passing safe upper limit

– (3) Clearance for working space/access to live parts - 2 ft. 6 in.



(c) Elevators, dumbwaiters, escalators, moving walks

– (1) Disconnecting means - Have single disconnecting means (ungrounded main power conductors)

– (2) Warning signs

– (3) Control panels

» Cabinets with doors

» Capable of being locked closed


(d) Electric welders/disconnection means

– (1) In supply circuit for

» Each motor - generated arc welder

» Each AC transformer

» Each DC rectifier arc welder

– (2) Switch/circuit breaker provided so resistance welders and control equipment isolated from supply circuit


Not equipped with disconnectin welder



(e) Data processing equipment

– Disconnecting means to all

»Electronic equipment in data processing and computer rooms

»Air conditioning system



(f) X-ray equipment - other than medical/dental use


» (i) In supply circuit

» Readily accessible from X-ray control

» (ii) High voltage switch or equivalent

– (2) Control

» (i) Radiographic/fluoroscopic types

» Effectively enclosed/interlocks

» (ii) Diffraction and irradiation types

» Energy indication



(g) Induction/dielectric heating equipment– (1) Scope

» Industrial» Scientific

– (2) Guarding/grounding» (i) Enclosures» (ii) Panel controls» (iii) Access to internal equipment» (iv) Warning labels - “Danger”» (v) Work applicator shielding» (vi) Disconnecting means



(h) Electrolytic cells– (1) Scope– (2) Definitions

» Cell line - assembly of electrically interconnected electrolytic cells supplied by DC power

» Cell line attachments/auxiliary equipment» Cell line working zone» Electrolytic cells

– (3) Application– (4) Disconnecting means– (5) Portable electric equipment



(h)(6) Power supply circuits and receptacles for portable electric equipment

(7) Fixed/portable electric equipment (8) Auxiliary non-electric connections (9) Cranes/hoists



(i) Electrically driven/controlled irrigation machines– (1) Lighting protection– (2) Disconnecting means

(j) Swimming pools, fountains, similar installations– (1) Scope– (2) Lighting and receptacles– (3) Cord/plug connected equipment– (4) Underwater equipment– (5) Fountains


Electrical Safety-Related Work Practices Standard

29 CFR 1910, Subpart S


1910.331 - Scope

Covers both qualified and unqualified persons working on, near or with electrical conductors and equipment.


1910.331 - Scope

Contains requirements for: Working on or near electrical equipment Use of electrical protective equipment The safe use of electrical equipment


1910.331 - Scope

Does not cover work by qualified persons on: Generation, transmission and distribution

installations Communication installations Installations in vehicles Railway installations


1910.332 - Training

Required for employees who face the risk of electrical shock


1910.332 - Content of Training

Electrical safe work practices Other safe work practices necessary for

safety


1910.332 - Content of Training

Distinguishing exposed live parts Determining normal voltage of parts Clearance distances and voltages

Qualified persons shall also be trained in:


1910.332 - Type of Training

Classroom or on the job,depth of training based on risk


1910.333 - Selection and Use of Work Practices

Safe work practices shall be used and beconsistent with the nature and extent of theassociated hazard.


1910.333(a)(1) - Selection and Use of Work Practices

Live parts to which an employee may be exposed shall be de-energized before the employee works on or near them, unless de-energizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations.

Live parts that operate at less than 50 volts to ground need not be de-energized if there will be no increased exposure to electrical burns or to explosion due to electrical arcs.


1910.333(a)(2) - Selection and Use of Work Practices

If the exposed live parts are not de-energized, other safety-related work practices shall be used to protect employees who may be exposed to the electrical hazards involved.


1910.333(b) - Working On or Near Exposed De-energized Parts

(2) While any employee is exposed to contact with parts of fixed electric equipment or circuits which have been de-energized, the circuits energizing parts shall be locked out or tagged out or both.


1910.333(b) - Working On or Near Exposed De-energized Parts

(2)(ii)(B) The circuits and equipment to be worked on shall be disconnected from all electric energy sources.

(2)(ii)(C) Stored electric energy which might endanger personnel shall be released.

(2)(ii)(D) Stored non-electrical energy in devices that could reenergize electric circuit parts shall be blocked or relieved to the extent that the circuit parts could not be accidentally energized by the device.


1910.333(c) - Working On or Near Exposed Energized Parts

(2) Only qualified persons may work on electrical circuit parts or equipment that have not been de-energized

(3) If work is to be performed near overhead lines, the lines shall be de-energized and grounded, or other protective measures shall be provided before work is started


1910.333(c)(3)Overhead Lines

(ii) When a qualified person is working in the vicinity of overhead lines, the person may not approach or take any conductive object without an approved insulating handle closer to exposed energized parts than shown in Table S-5 unless:

– (A) The person is insulated form the energized part

– (B) The energized part is insulated both from all other objects conductive objects

– (C) The person is insulated from all conductive objects


1910.333(c)(3)(iii) - Vehicular and Mechanical Equipment

Must be kept at least 10 ft away In transit, must be kept at least 4 ft. away Employees may not contact equipment if

approach distances can be violated

(Near overhead power lines)


1910.333(c)(4) - Illumination

(i) Employee may not enter spaces containing exposed energized parts, unless illumination is provided that enables the employees to perform the work safely.


1910.333(c)(5) - Confined or Enclosed Spaces

Employees working near exposed live parts shall be provided with and use protective shields, barriers or insulating materials in order to prevent inadvertent contact with live parts.


1910.333(c)(6) - Conductive Materials and Equipment

Conductive material must be used in safe manner

Safe work practices must be used when working with long, conductive objects


1910.333(c)(7) - Portable Ladders

Portable ladders shall be of nonconductive materials if they are used where the employee or the ladder could contact exposed energized parts.


1910.333(c)(8)Conductive Apparel

Conductive clothing and jewelry cannot be worn if they can come into contact with live parts


1910.333(c)(9)Housekeeping Duties

Adequate safety precautions and nonconductive cleaning materials must be used around live parts


1910.333(c)(10)Interlocks

Only a qualified person may temporarily defeat an interlock while working on equipment

Equipment must be returned to its operating condition


1910.334(a) - Portable Electrical Equipment

Cannot staple cord in place Cannot lift or lower by cord Check cord for defects Cords to have proper grounding Cords must be approved for location Safe work practices must be in place before

starting work


1910.335 - Safeguards for Personnel Protection

Employers must provide Employees must wear if exposed to hazards Must be maintained in a safe condition Non-conductive head protection must be

worn


1910.335(a)(2) - General Protective Equipment and Tools

(i) Appropriate insulated tools must be used around live parts

(ii) Protective shields and barriers must be used around live parts if they can be contacted


1910.335(b) - Alerting Techniques

Safety signs, tags, barricades and sometimes attendants must be used to alert employees of electrical hazards


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