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									    Subpart S
    Electrical
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   Subpart S

Electrical Standards
                                                1910.301
                                             Introduction

        (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 - 1910.399
National Safety Educational Center                            1-800-656-5317
                                     1910.302 - Electric
                                     Utilization Systems
   (a)   Scope
         –(1) Coverage
         –Equipment installations used within or on buildings,
            structures, and other premises, including:
        Yards                      Industrial substations
        Carnivals                  Conductors connecting
        Parking/Other lots          supply of electricity
        Mobile homes               Other outside conductors

        Recreational vehicles       on premises
National Safety Educational Center                    1-800-656-5317
                                  1910.302 - Electric
                           Utilization System (Cont)
   (a)(2) Not Covered:

     Ship installations              Railroad generating,
     Watercraft                       transforming,
     Railroad rolling stock
                                       transmitting or
                                       distribution of power
     Aircraft
                                      Communication
     Automotive vehicles
                                       equipment
      other than RV’s
                                      Electric utilities


National Safety Educational Center                       1-800-656-5317
                                 1910.302 - Electric
                         Utilization Systems (Cont)
(b) Extent of application
      (1) Requirements apply to all electrical installations
      (regardless of when designed and installed) in sections:

     — 1910.303(b)-(f)                — 1910.304(f)(3)-(4)
     — 1910.303(g)(2)                 — 1910.304(f)(5)(iv)(a)-(d)
     — 1910.304(e)(1)(i)              — 1910.304(f)(5)(v)-(vi)
     — 1910.304(e)(1)(iv)-(v)         — 1910.304(f)(6)(i)
     — 1910.304(f)(1)(ii)-(v)         — 1910.305(g)(1)(i)-(iii)
                                      — 1910.305(g)(2)(ii)-(iii)
 National Safety Educational Center                         1-800-656-5317
                                1910.302 - Electric
                        Utilization 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.




National Safety Educational Center               1-800-656-5317
                                                1910.303
                                     General 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

National Safety Educational Center                    1-800-656-5317
                                      1910.303 - General
                                     Requirements (Cont)

        (c) Splicing
          – Conductors joined or spliced by
                » Brazing
                » Welding
                » Soldering

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


National Safety Educational Center                   1-800-656-5317
                                      1910.303 - General
                                     Requirements (Cont)

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

National Safety Educational Center                   1-800-656-5317
                                      1910.303 - General
                                     Requirements (Cont)

        (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

National Safety Educational Center                   1-800-656-5317
                                     1910.303 - General
                                        Requirements (
        (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




National Safety Educational Center                                        1-800-656-5317
                                      1910.303 - General
                                     Requirements (Cont)

        (h) Over 600V
          – (3) Workspace about equipment
             » See Table S-2




National Safety Educational Center                   1-800-656-5317
                          1910.304 - Wiring Design
                                     and 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
National Safety Educational Center                       1-800-656-5317
                          1910.304 - Wiring Design
                              and 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”




National Safety Educational Center                                    1-800-656-5317
                          1910.304 - Wiring Design
                              and Protection (Cont)
   (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




National Safety Educational Center                                      1-800-656-5317
                          1910.304 - Wiring Design
                              and Protection (Cont)
   (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”




National Safety Educational Center                                        1-800-656-5317
                          1910.304 - Wiring Design
                              and Protection (Cont)
        (d) Services
          – (1) Disconnecting means
               » (i) General
                     Shall be provided to disconnect conductors (in buildings
                      or structures) from service entrance conductors
                     Indicators for open and closed positions
                     Readily accessible location nearest point of entrance of the
                      service-entrance conductors




National Safety Educational Center                                         1-800-656-5317
                          1910.304 - Wiring Design
                            and 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




National Safety Educational Center                             1-800-656-5317
                          1910.304 - Wiring Design
                              and Protection (Cont)
   (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




National Safety Educational Center                                       1-800-656-5317
                                        1910.304 - Wiring
                                     and 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)


National Safety Educational Center                     1-800-656-5317
                          1910.304 - Wiring Design
                              and Protection (Cont)

        (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


National Safety Educational Center                   1-800-656-5317
                          1910.304 - Wiring Design
                              and Protection (Cont)

        (f)(3) Grounding connections
        (4) Grounding path
          – Path to ground from circuits, equipment,
            enclosures - permanent and continuous




National Safety Educational Center                     1-800-656-5317
                          1910.304 - Wiring Design
                              and 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 locations
          operated at > 150V
          of types such as: refrigerators, A.C., hand-held motor tools,
           tools used in wet locations, portable hand lamps
National Safety Educational Center                            1-800-656-5317
                   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



National Safety Educational Center                      1-800-656-5317
                                      1910.305 - Wiring
                                     Methods, 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.



National Safety Educational Center                       1-800-656-5317
                                      1910.305 - Wiring
                                     Methods, etc. (Cont)

        (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



National Safety Educational Center                      1-800-656-5317
                                      1910.305 - Wiring
                                     Methods, etc. (Cont)

        (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




National Safety Educational Center                        1-800-656-5317
                                      1910.305 - Wiring
                                     Methods, etc. (Cont)

        (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




National Safety Educational Center                         1-800-656-5317
                                      1910.305 - Wiring
                                     Methods, etc. (Cont)
   (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


National Safety Educational Center                           1-800-656-5317
                                      1910.305 - Wiring
                                     Methods, etc. (Cont)

        (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


National Safety Educational Center                             1-800-656-5317
                                      1910.305 - Wiring
                                     Methods, etc. (Cont)

        (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




National Safety Educational Center                               1-800-656-5317
                                      1910.305 - Wiring
                                     Methods, etc. (Cont)

        (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




National Safety Educational Center                        1-800-656-5317
                                      1910.305 - Wiring
                                     Methods, etc. (Cont)
   (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




National Safety Educational Center                            1-800-656-5317
                    1910.306 - Specific Purpose
                    Equipment and Installations

        (a) Electric signs and outline lighting
          – (1) Disconnecting means
            (electronic/electromechanical controllers) -
             » Capable of being locked in open position




National Safety Educational Center                     1-800-656-5317
                    1910.306 - Specific Purpose
                             Equipment (Cont)
   (b) Cranes/Hoists
     – (1) Disconnecting means
         » 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.




National Safety Educational Center                              1-800-656-5317
                    1910.306 - Specific Purpose
                             Equipment (Cont)

        (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




National Safety Educational Center                          1-800-656-5317
                    1910.306 - Specific Purpose
                             Equipment (Cont)

        (d) Electric welders/disconnection means
          – (1) In supply circuit for
              » Each motor - generated arc welder
                                                        Not equipped
              » Each AC transformer
                                                        with disconnect
              » Each DC rectifier arc welder            in welder
          – (2) Switch/circuit breaker provided so resistance
             welders and control equipment isolated from supply
             circuit



National Safety Educational Center                            1-800-656-5317
                    1910.306 - Specific Purpose
                             Equipment (Cont)

        (e) Data processing equipment
          – Disconnecting means to all
             » Electronic equipment in data
               processing and computer rooms
             » Air conditioning system




National Safety Educational Center             1-800-656-5317
                    1910.306 - Specific Purpose
                             Equipment (Cont)
        (f) X-ray equipment - other than medical/dental use
          – (1) Disconnecting means
              » (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

National Safety Educational Center                             1-800-656-5317
                    1910.306 - Specific Purpose
                             Equipment (Cont)
        (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




National Safety Educational Center                    1-800-656-5317
                    1910.306 - Specific Purpose
                             Equipment (Cont)
        (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




National Safety Educational Center                                          1-800-656-5317
                    1910.306 - Specific Purpose
                             Equipment (Cont)

     (h)(6) Power supply circuits and receptacles
      for portable electric equipment
     (7) Fixed/portable electric equipment
     (8) Auxiliary non-electric connections
     (9) Cranes/hoists




National Safety Educational Center            1-800-656-5317
                    1910.306 - Specific Purpose
                             Equipment (Cont)
      (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
National Safety Educational Center                     1-800-656-5317
                   Electrical Safety-Related Work
                           Practices Standard
                      29 CFR 1910, Subpart S




National Safety Educational Center                  1-800-656-5317
                                     1910.331 - Scope

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




National Safety Educational Center                1-800-656-5317
                                     1910.331 - Scope

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




National Safety Educational Center                1-800-656-5317
                                     1910.331 - Scope

    Does not cover work by qualified persons on:
     Generation, transmission and distribution
      installations
     Communication installations
     Installations in vehicles
     Railway installations



National Safety Educational Center                1-800-656-5317
                                     1910.332 - Training


            Required for employees who face
            the risk of electrical shock




National Safety Educational Center                   1-800-656-5317
            1910.332 - Content of Training

     Electricalsafe work practices
     Other safe work practices necessary for
      safety




National Safety Educational Center       1-800-656-5317
            1910.332 - Content of Training
   Qualified persons shall also be trained in:
     Distinguishing exposed live parts
     Determining normal voltage of parts
     Clearance distances and voltages




National Safety Educational Center               1-800-656-5317
                   1910.332 - Type of Training

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




National Safety Educational Center                     1-800-656-5317
         1910.333 - Selection and Use of
                         Work Practices

        Safe work practices shall be used and be
        consistent with the nature and extent of the
        associated hazard.




National Safety Educational Center               1-800-656-5317
             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.

National Safety Educational Center                      1-800-656-5317
             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.




National Safety Educational Center               1-800-656-5317
        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.




National Safety Educational Center                1-800-656-5317
        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.
National Safety Educational Center                       1-800-656-5317
               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



National Safety Educational Center                     1-800-656-5317
                                            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




National Safety Educational Center                                        1-800-656-5317
      1910.333(c)(3)(iii) - Vehicular and
                Mechanical Equipment
                      (Near overhead power lines)
     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




National Safety Educational Center                  1-800-656-5317
                 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.




National Safety Educational Center              1-800-656-5317
                  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.




National Safety Educational Center               1-800-656-5317
                   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




National Safety Educational Center           1-800-656-5317
                                     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.




National Safety Educational Center                1-800-656-5317
                                         1910.333(c)(8)
                                     Conductive Apparel

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




National Safety Educational Center                  1-800-656-5317
                                          1910.333(c)(9)
                                     Housekeeping Duties

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




National Safety Educational Center                   1-800-656-5317
                                     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




National Safety Educational Center                1-800-656-5317
        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

National Safety Educational Center           1-800-656-5317
                          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




National Safety Educational Center              1-800-656-5317
                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




National Safety Educational Center            1-800-656-5317
                                            1910.335(b) -
                                     Alerting Techniques

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




National Safety Educational Center                    1-800-656-5317

								
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