1293 Airport Road

1
Subpart K Electrical 29 CFR 1926.400
Vincent J. Giblin, General President
Phone [phone] Fax [phone] E-mail
hazmat_at_iuoeiettc.org
1293 Airport Road Beaver, WV 25813
2

• 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.

3
Introduction

• Electricity is the flow of electrons through
• a conductor.

4
Introduction

• This flow is called a current. Any material
• that allows electrons to flow through it is a
• conductor. A good good example would
• be copper wire, allowing electricity to flow
• much like water through a hose.

5
Introduction

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

6
Introduction

• This brings up the topic of resistance.
• Insulators have high resistance to the current
• flow because it takes the path of least
• resistance which would be the conductor
• inside the insulator.

7
Introduction

• The human body can be used as a conductor,
• sending electrical
• currents through the
• body much like
• water through a
• sponge.

8
Introduction

• When you have had an electrical shock you may
• A. Stop breathing
• B. Burn the skin
• C. Cook internal organs
• D. Have internal bleeding
• E. Stop the heart

9
Introduction

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

10
Introduction

• A ground fault may be caused by the hot
• conductor coming into contact with an outlet
• or tool casing. The tool may continue to run
• until something touches the outlet or the tool
• case, thus creating a multiple path to ground
• and casing shock.

11
Introduction

• By using this standard, you will become
• aware of the electrical safety requirements
• that must be applied for the practical safe-
• guarding of employees using temporary or
• permanent electrical installations at a
• construction job-site.

12
Introduction

• This standard was first issued in 1971. It
• has since been updated in 1991. The
• subpart K is divided into four major
• divisions
• 1. 1926.402-408 Installation Safety
• Requirements
• 2. 1926.416 .417 Safety-Related Work
• Practices

13
Introduction

• The subpart K is divided into four major
• divisions
• 3. 1926.431 Safety-Related .432
  Maintenance
• Environmental Considerations
• 4. 1926.441 Safety Requirements
• for Special Equipment

14
Installation Safety Requirements1926-403 General
Requirements

• These general requirements would apply to
• all electrical conductors and equipment
• 1. Approved 5. Suitable
• 2. Strong and durable 6. Insulated
• 3. Heat and arc effects 7. Classified location
• 4. Safeguarding

15
Installation Safety Requirements1926-403 General
Requirements

• (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.

16
Installation Safety Requirements1926-403 General
Requirements

• (c) Interrupting rating
• Equipment intended to break current shall
• have an interrupting rating at system
• voltage sufficient for current that must be
• interrupted.

17
Installation Safety Requirements1926-403 General
Requirements

• (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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Installation Safety Requirements1926-403 General
Requirements

• (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

19
Installation Safety Requirements1926-403 General
Requirements

• (f) Arcing parts
• Electrical equipment
• producing arcs, sparks,
• flame, or molten metal
• shall be enclosed or
• separated from all
• combustible material

20
Installation Safety Requirements1926-403 General
Requirements

• (g) Marking
• Electrical equipment is not to be used unless
• it is properly marked with the manufacturers
• name or if it does not provide voltage,
• current, wattage, or other ratings necessary.

21
Installation Safety Requirements1926-403 General
Requirements

• (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.

22
Installation Safety Requirements1926-403 General
Requirements

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

23
Installation Safety Requirements1926-403 General
Requirements

• (i) 600 volts, nominal, or less
• Clear spaces are not to be used for storage.
• There should be at least one entrance for access
  to the working space about electric equipment
• The working space in front of service equipment
• that is exposed should not be less than 3
  feet and the minimum headroom shall be 63.

24
Installation Safety Requirements1926-403 General
Requirements

• (i) 600 volts, nominal, or less
• Live 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.

25
Installation Safety Requirements1926-403 General
Requirements

• (j) Over 600 volts, nominal
• This 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.

26
Installation Safety Requirements1926-403 General
Requirements

• (j) Over 600 volts, nominal
• Sufficient space is needed to permit ready and
  safe operation and maintenance. The minimum
  clear workspace shall not be less than 66 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 66
  high.

27
Installation Safety Requirements1926-403 General
Requirements

• (j) Over 600 volts, nominal
• The 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 Protection

• (a) Conductors used as either grounded or as
• an equipment grounding conductor are to be
• distinguishable from all other conductors.
• Grounded- Neutral color, current carrying
  conductor
• Grounding- Bare or green color dedicated to frames

29
1926.404 Wiring Design and Protection

• The polarity connections shall not be changed
• by the use of grounded conductors. A
• grounding terminal or device on a receptacle,
• cord connector,or attachment plug shall not be
• used for purposes other than grounding.

30
1926.404 Wiring Design and Protection

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

31
1926.404 Wiring Design and Protection

• (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

32
1926.404 Wiring Design and Protection

• (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

33
1926.404 Wiring Design and Protection

• (c) Outside conductors and lamps
• (ii) Clearance from ground
• 10 ft - above sidewalks, grade, platform
• 12 ft - vehicular traffic
• 15 ft - other than public streets, alleys,
  roads, and driveways
• 18 ft - above public streets, alley, roads,
  and driveway

34
1926.404 Wiring Design and Protection

• (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

35
1926.404 Wiring Design and Protection

• (c) Outside conductors and lamps
• Outdoor lamps are to be located below all live
• conductors, or electric equipment unless
• other specific safeguards are required for
• relamping.

36
1926.404 Wiring Design and Protection

• (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.

37
1926.404 Wiring Design and Protection

• (e) Overcurrent protection- (1)600 volts or less
• Protection of conductors and equipment from
• overcurrent of circuits can be done by making
• certain
• (i) Conductors have sufficient ampacity for
  job
• ( ii) No interruptions from overcurrent devices

38
1926.404 Wiring Design and Protection

• (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

39
1926.404 Wiring Design and Protection

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

40
1926.404 Wiring Design and Protection

• (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.

41
1926.404 Wiring Design and Protection

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

42
1926.404 Wiring Design and Protection

• (f)(7) Equipment connected by cord and plug
• that must be grounded.
• 1. Handheld motor-operated tools
• 2. 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 equipment
• 4. Tools used in wet and/or conductive locations

43
1926.404 Wiring Design and Protection

• (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.

44
1926.404 Wiring Design and Protection

• (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

45
1926.404 Wiring Design and Protection

• (f) Grounding
• Systems to be grounded
• 3 wire DC systems
• 2 wire DC systems
• AC circuit less than 50 volts
• AC circuits 50 volts to 1000 volts
• Exempted if less than 50 volts and isolation
• transformer and also if double insulated.

46
1926.405 Wiring Methods, Components, 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.

47
1926.405 Wiring Methods, Components, and Equipment

• Temporary power and wiring methods shall
• be removed immediately upon completion of
• construction or the purpose for which the
• wiring was installed.
• The general requirements for temporary
• wiring are listed in (a)(2)(ii)(A-J).

48
1926.405 Wiring Methods, Components, and Equipment

• Covering lights in this section ,(F-G),
• temporary lights shall not be suspended by
• their electric cords unless cords and lights are
• designed for this means of suspension.

49
1926.405 Wiring Methods, Components, and Equipment

• Portable electric lighting used in wet and/or
• other conductive locations, such as drums,
• tanks, and vessels, shall be operated at 12 volts
• or less. 120-volt lights may be used if protected
• by a ground-fault circuit interrupter.

50
1926.405 Wiring Methods, Components, and Equipment

• Covering, also,the commonly used flexible
• extension cords and cables, section (I). They
  are
• to be protected from damage as they may pass
• through doorways or other pinch joints. Sharp
• corners and projections shall be avoided. Never
• pass extension cords through walls, floors,
• ceilings, windows, or doors.

51
1926.405 Wiring Methods, Components, and Equipment

• (J) explains extension cords shall be of
  three-wire
• type and designed for hard or extra-hard usage,
  as
• in those used by portable lights.
• Never use a cord without a ground, the odds
• increase that a fault current will flow through
  you.

52
1926.405 Wiring Methods, Components, and Equipment

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

53
1926.405 Wiring Methods, Components, and Equipment

• (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.

54
1926.405 Wiring Methods, Components, and Equipment

• (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.

55
1926.405 Wiring Methods, Components, and Equipment

• (d) Switchboards and panelboards.
• Switchboards with exposed
• live parts are to be located
• in permanently dry locations
• and accessible only to qualified
• persons. They should be
• mounted appropriately and
• have dead fronts.

56
1926.405 Wiring Methods, Components, and Equipment

• (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.

57
1926.405 Wiring Methods, Components, and Equipment

• (g) Flexible cords and cables are to used only
  for
• A. Pendants B. Fixture wiring
• C. Portable appliances D. Elevator cables
• E. Crane/Hoist wiring
• F. Connection of stationary equipment
• G. Noise/Vibration prevention
• H. Removable connections for maintenance

58
1926.405 Wiring Methods, Components, and Equipment

• (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.

59
1926.405 Wiring Methods, Components, and Equipment

• (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. Transformers
• 4. Motors 6. Capacitors

60
1926.406 Specific purpose equipment and
installations

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

61
1926.407 Hazardous Locations

• This section covers requirements for electric
• equipment and wiring in locations which are
• classified depending on the properties of the
• flammable vapors, liquids or gases, or
• combustible dusts or fibers which may be
• present.

62
1926.407 Hazardous Locations

• These hazardous locations are assigned six
• designations as follows
• Class I - Division1 and 2 - Gasses Vapors
• Class II - Division 1 and 2 - Dusts
• Class III - Division 1 and 2 - Fibers

63
1926.407 Hazardous Locations

• 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).

64
1926.408 Special systems

• (a) Systems over 600 volts
• (b) Class 1, Class 2, Class 3 remote control,
  signaling, and power-limited circuits
• (c) Communication systems

65
1926.416 Safety-Related Work 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

66
1926.417 Lockout and tagging of circuits

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

67
1926.431 Maintenance of equipment

• 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.

68
1926.432 Environmental deterioration 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.

69
1926.432 Environmental deterioration 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.

70
1926.441 Batteries and battery charging

• (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.

71
1926.441 Batteries and battery charging

• (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.

72

• 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.

73
End

• 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.