1293 Airport Road Beaver, WV 25813

1293 Airport RoadBeaver, WV 25813

Phone: (304) 253-8674Fax: (304) 253-7758

E-mail: [email protected]

Subpart K Electrical29 CFR 1926.400

Vincent J. Giblin, General President

This material was produced under grant number 46C5-HT16 from the Occupational Safety and

Health Administration, U.S. Department of Labor. It does not necessarily reflect the views or policies of the U.S. Department of Labor, nor

does mention of trade names, commercial products, or organizations imply endorsement by

the U.S. Government.

Operating Engineers National Hazmat Program

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IntroductionIntroductionElectricity is the flow of electrons througha conductor.


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IntroductionIntroduction

This flow is called a current. Any materialthat allows electrons to flow through it is aconductor. A good good example wouldbe copper wire, allowing electricity to flowmuch like water through a hose.


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This conductor must be covered by aninsulator made of materials that do not conduct electricity easily. Glass, rubber, plastic, and dry wood are insulators.


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IntroductionIntroductionThis brings up the topic of resistance.Insulators have high resistance to the currentflow because it takes the path of leastresistance which would be the conductor inside the insulator.


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The human body can be used as a conductor, sending electrical currents through thebody much likewater through asponge.


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When you have had an electrical shock you may:

A. Stop breathingB. Burn the skinC. Cook internal organsD. Have internal bleedingE. Stop the heart


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This - of course - is to be avoided. What maycause this to happen? It could be a shortcircuit or a ground fault.A short circuit may happen when two hotwires or a hot wire and a neutral wire of a circuit contact each other. This causes the resistance to lower.


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A ground fault may be caused by the hotconductor coming into contact with an outletor tool casing. The tool may continue to rununtil something touches the outlet or the toolcase, thus creating a multiple path to groundand casing shock.


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By using this standard, you will becomeaware of the electrical safety requirementsthat must be applied for the practical safe-guarding of employees using temporary orpermanent electrical installations at aconstruction job-site.


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This standard was first issued in 1971. Ithas since been updated in 1991. Thesubpart K is divided into four majordivisions:1. 1926.402-408: Installation Safety Requirements2. 1926.416 & .417: Safety-Related Work Practices


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The subpart K is divided into four majordivisions:

3. 1926.431 Safety-Related & .432: Maintenance &

Environmental Considerations4. 1926.441: Safety Requirements for Special Equipment


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Installation Safety RequirementsInstallation Safety Requirements1926-403 General Requirements1926-403 General Requirements

These general requirements would apply to all electrical conductors and equipment:1. Approved 5. Suitable2. Strong and durable 6. Insulated3. Heat and arc effects 7. Classified

location4. Safeguarding


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(a) Approval of all electrical conductors and equipment shall be approved.(b) Examination, installation, and use of equipment. The employer is to ensure that electrical equipment is free from recognized hazards that are likely to cause death or serious physical harm to employees.


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(c) Interrupting rating: Equipment intended to break current shall

have an interrupting rating at system voltage sufficient for current that must be interrupted.


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(d) Mounting and cooling of equipment: Mounting-Electric equipment is to be

firmly secured to the surface on which it is mounted. No wooden plugs are to be used.

Cooling- Electrical equipment depending upon the natural circulation of air is to be installed so that the air floe is not hindered by any obstacles.


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(e) Splices:Conductors are to be spliced or joined with

splicing devices designed for the use or by brazing, welding, or soldering with a fusible metal or alloy. Splices, joints, and free ends are t be covered with proper insulation


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(f) Arcing parts:Electrical equipment producing arcs, sparks,flame, or molten metalshall be enclosed orseparated from allcombustible material


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(g) Marking:Electrical equipment is not to be used unless

it is properly marked with the manufacturer’s name or if it does not provide voltage, current, wattage, or other ratings necessary.


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(h) Identification of disconnecting means and circuits:Each disconnecting means shall be legibly

marked to indicate its purpose. Each service, feeder, and branch circuit shall be legibly marked to indicate its purpose.


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(i) 600 volts, nominal, or lessWorking Clearances are to follow Table K-1

Table K-1


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(i) 600 volts, nominal, or lessClear spaces are not to be used for storage.There should be at least one entrance for access to the working space about electric equipmentThe working space in front of service equipment

that is exposed should not be less than 3 feet and the minimum headroom shall be 6’3”.


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(i) 600 volts, nominal, or lessLive parts of electric equipment are to be guarded against accidental contact. Partitions, screens, and placement on elevated levels of 8 feet or more above the work surface, are all means of guarding and are to be accessible only to qualified persons.


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(j) Over 600 volts, nominalThis electrical equipment shall be surrounded by a wall, screen, or fence, access to which is controlled by lock and key or under the observation of a qualified person at all times.Those installations that have exposed live parts are to be accessible to qualified persons only.


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(j) Over 600 volts, nominalSufficient space is needed to permit ready and safe operation and maintenance. The minimum clear workspace shall not be less than 6’6” high, or less than 3’ wide with adequate space to permit at lest a 90o opening or doors or panels.There should be at least one entrance to this

work space not less than 24” wide and 6’6” high.


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(j) Over 600 volts, nominalThe minimum clear working space in front of electric equipment shall not be less than specified in Table K-2


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1926.404 Wiring Design and 1926.404 Wiring Design and ProtectionProtection

(a) Conductors used as either grounded or asan equipment grounding conductor are to bedistinguishable from all other conductors.Grounded- Neutral color, current carrying

conductorGrounding- Bare or green color dedicated to

frames


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The polarity connections shall not be changedby the use of grounded conductors. Agrounding terminal or device on a receptacle,cord connector,or attachment plug shall not beused for purposes other than grounding.


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(b) Branch circuits are used for ground-faultprotection. Ground fault circuit interrupters oran assured equipment grounding conductor program are to be used to protect the employees on the construction site. repairs


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(c) Outside conductors and lamps(i) Power Conductors on poles are to be separated from communication conductors as follows:

30 inches if below communication conductors


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(c) Outside conductors and lamps(i) Power Conductors on poles are to be separated from communication conductors as follows:

24 inches if above communication and 300 volts or less 30 inches if above communication and more than 300 volts


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(c) Outside conductors and lamps(ii) Clearance from ground: 10 ft - above sidewalks, grade, platform12 ft - vehicular traffic15 ft - other than public streets, alleys, roads, and driveways18 ft - above public streets, alley, roads, and driveway


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(c) Outside conductors and lamps(iii) Clearance from building openings is

to be at least 3 feet(iv) Clearance over roofs 8 ft - insulated conductors 10 ft - covered conductors 15 ft - bare conductors 18 ft - if used for vehicles


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(c) Outside conductors and lampsOutdoor lamps are to be located below all live

conductors, or electric equipment unless other specific safeguards are required for relamping.


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(d) Services Means will be provided to disconnect all

conductors in a building or other structure from the service-entrance conductors, indicating whether it is in the open or closed position. They shall be installed at a readily accessible location nearest the point of entrance of the service-entrance conductors.


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(e) Overcurrent protection- (1)600 volts or lessProtection of conductors and equipment fromovercurrent of circuits can be done by makingcertain:

(i) Conductors have sufficient ampacity for job( ii) No interruptions from overcurrent devices


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(e) Overcurrent protection-(1) 600 volts or less(iii) All cartridge fuses are provided with disconnecting means.(iv) Overcurrent devices are readily accessible(v) Fuses, circuit breakers, and moving parts are shielded to protect employees(vi) Circuit breakers are clearly ON of OFF


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(e) Overcurrent protection-(2) 600 volts or moreFeeders and branch circuits over 600 volts, nominal, shall have short-circuit protection.


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(f) Grounding Grounding keeps you from becoming part of the

circuit by providing a separate low resistance pathway for electricity when it does not follow normal flow from hot to neutral.

OSHA lists extensive requirements for grounding in (f)(1) through(11), focusing on things that give a continuous grounding path.


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(f) GroundingIn order to assure proper grounding, the path must: Be permanent and continuous Be of ample capacity Have low resistance Bond all circuit parts together


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(f)(7) Equipment connected by cord and plug that must be grounded.1. Handheld motor-operated tools2. Equipment used in damp or wet locations or by

employees standing on the ground or on metal floors or working inside of metal tanks or boilers

3. Portable and mobile X-ray equipment4. Tools used in wet and/or conductive locations


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(f)(11) Grounding of systems and circuits of 1000 volts and over

1. Portable and mobile high voltage equipment shall be supplied from a system having its neutral grounded through an impedance.

2. Provided ground-fault protection is to automatically de-energize any high voltage system component which has developed a ground fault.


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(f)(11) Grounding of systems and circuits of 1000 volts and over

3. The grounding electrode to which the portable or mobile equipment system neutral impedance is connected shall be isolated from and separated in the ground by at least 20 feet from any other system or equipment grounding electrode


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(f) Grounding Systems to be grounded3 wire DC systems

2 wire DC systemsAC circuit less than 50 voltsAC circuits 50 volts to 1000 volts

Exempted if less than 50 volts and isolationtransformer and also if double insulated.


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1926.405 Wiring Methods, 1926.405 Wiring Methods, Components, and EquipmentComponents, and Equipment

We will touch briefly on each of the elements of this section.(a)In discussing the general requirements of

wiring methods, metal raceways, cable armor, and other metal enclosures for conductors shall be metallically joined together into a continuous electric conductor.


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Temporary power and wiring methods shallbe removed immediately upon completion ofconstruction or the purpose for which thewiring was installed.The general requirements for temporarywiring are listed in (a)(2)(ii)(A-J).


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Covering lights in this section ,(F-G),temporary lights shall not be suspended bytheir electric cords unless cords and lights aredesigned for this means of suspension.


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Portable electric lighting used in wet and/orother conductive locations, such as drums,tanks, and vessels, shall be operated at 12 voltsor less. 120-volt lights may be used if

protectedby a ground-fault circuit interrupter.


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Covering, also,the commonly used flexibleextension cords and cables, section (I). They areto be protected from damage as they may passthrough doorways or other pinch joints. Sharpcorners and projections shall be avoided. Neverpass extension cords through walls, floors,ceilings, windows, or doors.


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(J) explains extension cords shall be of three-wiretype and designed for hard or extra-hard usage, asin those used by portable lights. Never use a cord without a ground, the oddsincrease that a fault current will flow through

you.


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(b)Conductors entering boxes, cabinets, or fittings are to be protected from abrasion. Openings through which conductors enter andthose not in use shall be effectively closed.These boxes and fittings shall be provided withthe appropriate covers.


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(c) Knife switches:Single-throw knife switches shall be so connected that the blades are dead when the switch is in the open position. They are to be placed so that gravity will not tend to close them and have a locking device that ensures the blades remain in the open position when set.


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(c) Knife switches:Double-throw knife switches may be mounted so that the throw will be either vertical or horizontal. A locking device shall be provided to ensure the blades remain in the open position when so set.


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(d) Switchboards and panelboards.Switchboards with exposedlive parts are to be located in permanently dry locationsand accessible only to qualifiedpersons. They should bemounted appropriately and have dead fronts.


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(e) Proper Enclosures for damp or wet locations are to prevent moisture or water from entering and accumulating within the enclosures. For this reason, switches and circuit breakers are to be placed in weatherproof enclosures.

(f) All conductors used for general wiring shall be insulated unless otherwise permitted in this Subpart.


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(g) Flexible cords and cables are to used only for:

A. Pendants B. Fixture wiringC. Portable appliances D. Elevator cablesE. Crane/Hoist wiringF. Connection of stationary equipmentG. Noise/Vibration preventionH. Removable connections for maintenance


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(h) Portable cables over 600 volts shall consist of No. 8 or larger conductors employingflexible stranding. Cables operated at over 2000 volts are to be shielded in order to confine the voltage stresses to the insulation.

(i) Fixture wires are to be suitable for the voltage, temperature, and location of use.


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(j) Requirements are covered fore general equipment use inclusive of:

1. Lighting fixtures, lampholders, lamps and receptacles

2. Receptacles, cord connectors, and attachment plugs

3. Appliances 5. Transformers4. Motors 6. Capacitors


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1926.406 Specific purpose 1926.406 Specific purpose equipment and installationsequipment and installations

(a) Cranes and hoists(b) Elevators, escalators, walks(c) Electric welders-disconnecting means (d) X-ray equipment


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1926.407 Hazardous Locations1926.407 Hazardous Locations

This section covers requirements for electricequipment and wiring in locations which areclassified depending on the properties of theflammable vapors, liquids or gases, orcombustible dusts or fibers which may bepresent.


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These hazardous locations are assigned sixdesignations as follows:

Class I - Division1 and 2 - Gasses & Vapors Class II - Division 1 and 2 - DustsClass III - Division 1 and 2 - Fibers


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Electrical installations of equipment in hazardous locations shall be approved as intrinsically safe (permitted in any hazardous location included in its listing or labeling) or approved for the hazardous location (class of location and ignitable or combustible properties of any specific element present).


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1926.408 Special systems1926.408 Special systems

(a) Systems over 600 volts(b) Class 1, Class 2, Class 3 remote control,

signaling, and power-limited circuits(c) Communication systems


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1926.416 Safety-Related 1926.416 Safety-Related Work PracticesWork Practices

(a) Protection of employees(b) Passageways and open spaces(c) Load ratings(d) Fuses(e) Cords and cables(f) Interlocks(g) Use of equipment


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1926.417 Lockout and 1926.417 Lockout and tagging of circuitstagging of circuits

(a) Controls(b) Equipment and circuits(c) Tags(d) Lockout and tagging


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1926.431 Maintenance of 1926.431 Maintenance of equipmentequipment

The employer shall ensure that all wiring components and utilization equipment in hazardous locations are maintained in a dust-tight, dust-ignition-proof, or explosion-proof condition, as appropriate.


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1926.432 Environmental 1926.432 Environmental deterioration of equipmentdeterioration of equipment

(a) Deteriorating agents 1. Damp or wet locations 2. Exposure to gases, fumes, vapors, liquids, or other agents having a deteriorating effect on the conductors or equipment 3. Exposure to excessive temperatures.


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1926.432 Environmental 1926.432 Environmental deterioration of equipmentdeterioration of equipment

(b) Protection against corrosion. Metal raceways, cable armor, boxes, cable sheathing, cabinets, elbows, couplings, fittings, supports, and support hardware shall be of materials appropriate for the environment in which they are to be installed.


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1926.441 Batteries and battery 1926.441 Batteries and battery chargingcharging

(1) Unsealed batteries are to be located in well ventilated areas to (2)ensure diffusion of the gases and prevent the accumulation of and explosive mixture. (3)Substantial racks and trays are to be supplied and treated to make them resistant to the electrolyte. (4) Floors are to be acid resistant and (5) workers who handle acids or batteries are to be provided with face shields, aprons,and rubber gloves.


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1926.441 Batteries and battery 1926.441 Batteries and battery chargingcharging

(6) Facilities for quick drenching of the eyes and body shall be provided within 25 feet of battery handling areas.

(7) Facilities shall be provided for flushing and neutralizing spilled electrolyte and for fire protection.

This material was produced under grant number 46C5-HT16 from the Occupational Safety and

Health Administration, U.S. Department of Labor. It does not necessarily reflect the views or policies of the U.S. Department of Labor, nor

does mention of trade names, commercial products, or organizations imply endorsement by

the U.S. Government.


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EndEnd

This publication was made possible by grant numbers 5 U45 ES06182-13 AND 5 U45 ES09763-13 from the National Institute of Environmental Health Sciences (NIEHS), NIH. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS, NIH.

1293 Airport Road Beaver, WV 25813

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