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this section, may normally be done
without mechanical ventilation or respiratory protective equipment, but
where, because of unusual physical or
atmospheric conditions, an unsafe accumulation of contaminants exists,
suitable mechanical ventilation or respiratory protective equipment shall be
provided.
(2) Employees performing any type of
welding, cutting, or heating shall be
protected by suitable eye protective
equipment in accordance with the requirements of subpart E of this part.
[44 FR 8577, Feb. 9, 1979; 44 FR 20940, Apr. 6,
1979, as amended at 55 FR 42328, Oct. 18, 1990;
58 FR 35179, June 30, 1993]
§ 1926.354 Welding, cutting, and heating in way of preservative coatings.
(a) Before welding, cutting, or heating is commenced on any surface covered by a preservative coating whose
flammability is not known, a test shall
be made by a competent person to determine its flammability. Preservative
coatings shall be considered to be highly flammable when scrapings burn with
extreme rapidity.
(b) Precautions shall be taken to prevent ignition of highly flammable
hardened preservative coatings. When
coatings are determined to be highly
flammable, they shall be stripped from
the area to be heated to prevent ignition.
(c) Protection against toxic preservative coatings: (1) In enclosed spaces, all
surfaces covered with toxic preservatives shall be stripped of all toxic coatings for a distance of at least 4 inches
from the area of heat application, or
the employees shall be protected by air
line respirators, meeting the requirements of subpart E of this part.
(2) In the open air, employees shall be
protected by a respirator, in accordance with requirements of subpart E of
this part.
(d) The preservative coatings shall be
removed a sufficient distance from the
area to be heated to ensure that the
temperature of the unstripped metal
will not be appreciably raised. Artificial cooling of the metal surrounding
the heating area may be used to limit
the size of the area required to be
cleaned.
§ 1926.402
Subpart K—Electrical
AUTHORITY: Sections 6 and 8 of the Occupational Safety and Health Act of 1970 (29
U.S.C. 655 and 657); sec. 107, Contract Work
Hours and Safety Standards Act (40 U.S.C.
333); Secretary of Labor’s Order No. 9–83 (48
FR 35736) or 1–90 (55 FR 9033), as applicable;
29 CFR part 1911.
SOURCE: 51 FR 25318, July 11, 1986, unless
otherwise noted.
GENERAL
§ 1926.400
Introduction.
This subpart addresses electrical
safety requirements that are necessary
for the practical safeguarding of employees involved in construction work
and is divided into four major divisions
and applicable definitions as follows:
(a) Installation safety requirements. Installation safety requirements are contained in §§ 1926.402 through 1926.408. Included in this category are electric
equipment and installations used to
provide electric power and light on
jobsites.
(b) Safety-related work practices. Safety-related work practices are contained
in §§ 1926.416 and 1926.417. In addition to
covering the hazards arising from the
use of electricity at jobsites, these regulations also cover the hazards arising
from the accidental contact, direct or
indirect, by employees with all energized lines, above or below ground,
passing through or near the jobsite.
(c) Safety-related maintenance and environmental considerations. Safety-related maintenance and environmental
considerations
are
contained
in
§§ 1926.431 and 1926.432.
(d) Safety requirements for special
equipment. Safety requirements for special equipment are contained in
§ 1926.441.
(e) Definitions. Definitions applicable
to this subpart are contained in
§ 1926.449.
§ 1926.401
[Reserved]
INSTALLATION SAFETY REQUIREMENTS
§ 1926.402
Applicability.
(a) Covered. Sections 1926.402 through
1926.408 contain installation safety requirements for electrical equipment
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§ 1926.403
29 CFR Ch. XVII (7–1–14 Edition)
and installations used to provide electric power and light at the jobsite.
These sections apply to installations,
both temporary and permanent, used
on the jobsite; but these sections do
not apply to existing permanent installations that were in place before the
construction activity commenced.
NOTE: If the electrical installation is made
in accordance with the National Electrical
Code ANSI/NFPA 70–1984, exclusive of Formal Interpretations and Tentative Interim
Amendments, it will be deemed to be in compliance with §§ 1926.403 through 1926.408, except for §§ 1926.404(b)(1) and 1926.405(a)(2)(ii)
(E), (F), (G), and (J).
(b) Not covered. Sections 1926.402
through 1926.408 do not cover installations used for the generation, transmission, and distribution of electric
energy, including related communication, metering, control, and transformation
installations.
(However,
these regulations do cover portable and
vehicle-mounted generators used to
provide power for equipment used at
the jobsite.) See subpart V of this part
for the construction of power distribution and transmission lines.
§ 1926.403 General requirements.
(a) Approval. All electrical conductors and equipment shall be approved.
(b) Examination, installation, and use
of equipment—(1) Examination. The employer shall ensure that electrical
equipment is free from recognized hazards that are likely to cause death or
serious physical harm to employees.
Safety of equipment shall be determined on the basis of the following
considerations:
(i) Suitability for installation and
use in conformity with the provisions
of this subpart. Suitability of equipment for an identified purpose may be
evidenced by listing, labeling, or certification for that identified purpose.
(ii) Mechanical strength and durability, including, for parts designed to
enclose and protect other equipment,
the adequacy of the protection thus
provided.
(iii) Electrical insulation.
(iv) Heating effects under conditions
of use.
(v) Arcing effects.
(vi) Classification by type, size, voltage, current capacity, specific use.
(vii) Other factors which contribute
to the practical safeguarding of employees using or likely to come in contact with the equipment.
(2) Installation and use. Listed, labeled, or certified equipment shall be
installed and used in accordance with
instructions included in the listing, labeling, or certification.
(c) Interrupting rating. Equipment intended to break current shall have an
interrupting rating at system voltage
sufficient for the current that must be
interrupted.
(d) Mounting and cooling of equipment—(1) Mounting. Electric equipment
shall be firmly secured to the surface
on which it is mounted. Wooden plugs
driven into holes in masonry, concrete,
plaster, or similar materials shall not
be used.
(2) Cooling. Electrical equipment
which depends upon the natural circulation of air and convection principles for cooling of exposed surfaces
shall be installed so that room air flow
over such surfaces is not prevented by
walls or by adjacent installed equipment. For equipment designed for floor
mounting, clearance between top surfaces and adjacent surfaces shall be
provided to dissipate rising warm air.
Electrical equipment provided with
ventilating openings shall be installed
so that walls or other obstructions do
not prevent the free circulation of air
through the equipment.
(e) Splices. Conductors shall be
spliced or joined with splicing devices
designed for the use or by brazing,
welding, or soldering with a fusible
metal or alloy. Soldered splices shall
first be so spliced or joined as to be mechanically and electrically secure
without solder and then soldered. All
splices and joints and the free ends of
conductors shall be covered with an insulation equivalent to that of the conductors or with an insulating device
designed for the purpose.
(f) Arcing parts. Parts of electric
equipment which in ordinary operation
produce arcs, sparks, flames, or molten
metal shall be enclosed or separated
and isolated from all combustible material.
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Occupational Safety and Health Admin., Labor
(g) Marking. Electrical equipment
shall not be used unless the manufacturer’s name, trademark, or other descriptive marking by which the organization responsible for the product may
be identified is placed on the equipment and unless other markings are
provided giving voltage, current, wattage, or other ratings as necessary. The
marking shall be of sufficient durability to withstand the environment involved.
(h) Identification of disconnecting
means and circuits. Each disconnecting
means required by this subpart for motors and appliances shall be legibly
marked to indicate its purpose, unless
located and arranged so the purpose is
evident. Each service, feeder, and
branch circuit, at its disconnecting
means or overcurrent device, shall be
legibly marked to indicate its purpose,
unless located and arranged so the purpose is evident. These markings shall
be of sufficient durability to withstand
the environment involved.
(i) 600 Volts, nominal, or less. This
paragraph applies to equipment operating at 600 volts, nominal, or less.
(1) Working space about electric equipment. Sufficient access and working
space shall be provided and maintained
about all electric equipment to permit
ready and safe operation and maintenance of such equipment.
(i) Working clearances. Except as required or permitted elsewhere in this
subpart, the dimension of the working
space in the direction of access to live
parts operating at 600 volts or less and
likely to require examination, adjustment, servicing, or maintenance while
alive shall not be less than indicated in
Table K–1. In addition to the dimensions shown in Table K–1, workspace
shall not be less than 30 inches (762
mm) wide in front of the electric equipment. Distances shall be measured
from the live parts if they are exposed,
or from the enclosure front or opening
if the live parts are enclosed. Walls
constructed of concrete, brick, or tile
are considered to be grounded. Working
space is not required in back of assemblies such as dead-front switchboards
or motor control centers where there
are no renewable or adjustable parts
such as fuses or switches on the back
and where all connections are acces-
§ 1926.403
sible from locations other than the
back.
TABLE K–1—WORKING CLEARANCES
Minimum clear distance
for conditions 1
Nominal voltage to ground
0–150 .........................................
151–600 .....................................
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(b)
(c)
Feet 2
3
31⁄2
Feet 2
3
4
1 Conditions (a), (b), and (c) are as follows: (a) Exposed live
parts on one side and no live or grounded parts on the other
side of the working space, or exposed live parts on both sides
effectively guarded by insulating material. Insulated wire or insulated busbars operating at not over 300 volts are not considered live parts. (b) Exposed live parts on one side and
grounded parts on the other side. (c) Exposed live parts on
both sides of the workspace [not guarded as provided in Condition (a)] with the operator between.
2 Note:
For International System of Units (SI): one
foot=0.3048m.
(ii) Clear spaces. Working space required by this subpart shall not be used
for storage. When normally enclosed
live parts are exposed for inspection or
servicing, the working space, if in a
passageway or general open space,
shall be guarded.
(iii) Access and entrance to working
space. At least one entrance shall be
provided to give access to the working
space about electric equipment.
(iv) Front working space. Where there
are live parts normally exposed on the
front of switchboards or motor control
centers, the working space in front of
such equipment shall not be less than 3
feet (914 mm).
(v) Headroom. The minimum headroom of working spaces about service
equipment, switchboards, panelboards,
or motor control centers shall be 6 feet
3 inches (1.91 m).
(2) Guarding of live parts. (i) Except as
required or permitted elsewhere in this
subpart, live parts of electric equipment operating at 50 volts or more
shall be guarded against accidental
contact by cabinets or other forms of
enclosures, or by any of the following
means:
(A) By location in a room, vault, or
similar enclosure that is accessible
only to qualified persons.
(B) By partitions or screens so arranged that only qualified persons will
have access to the space within reach
of the live parts. Any openings in such
partitions or screens shall be so sized
and located that persons are not likely
to come into accidental contact with
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Feet 2
3
3
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§ 1926.403
29 CFR Ch. XVII (7–1–14 Edition)
the live parts or to bring conducting
objects into contact with them.
(C) By location on a balcony, gallery,
or platform so elevated and arranged as
to exclude unqualified persons.
(D) By elevation of 8 feet (2.44 m) or
more above the floor or other working
surface and so installed as to exclude
unqualified persons.
(ii) In locations where electric equipment would be exposed to physical
damage, enclosures or guards shall be
so arranged and of such strength as to
prevent such damage.
(iii) Entrances to rooms and other
guarded locations containing exposed
live parts shall be marked with conspicuous warning signs forbidding unqualified persons to enter.
(j) Over 600 volts, nominal—(1) General.
Conductors and equipment used on circuits exceeding 600 volts, nominal,
shall comply with all applicable provisions of paragraphs (a) through (g) of
this section and with the following provisions which supplement or modify
those requirements. The provisions of
paragraphs (j)(2), (j)(3), and (j)(4) of this
section do not apply to equipment on
the supply side of the service conductors.
(2) Enclosure for electrical installations.
Electrical installations in a vault,
room, closet or in an area surrounded
by a wall, screen, or fence, access to
which is controlled by lock and key or
other equivalent means, are considered
to be accessible to qualified persons
only. A wall, screen, or fence less than
8 feet (2.44 m) in height is not considered adequate to prevent access unless
it has other features that provide a degree of isolation equivalent to an 8-foot
(2.44-m) fence. The entrances to all
buildings, rooms or enclosures containing exposed live parts or exposed
conductors operating at over 600 volts,
nominal, shall be kept locked or shall
be under the observation of a qualified
person at all times.
(i) Installations accessible to qualified
persons only. Electrical installations
having exposed live parts shall be accessible to qualified persons only and
shall comply with the applicable provisions of paragraph (j)(3) of this section.
(ii) Installations accessible to unqualified persons. Electrical installations
that are open to unqualified persons
shall be made with metal-enclosed
equipment or shall be enclosed in a
vault or in an area, access to which is
controlled by a lock. Metal-enclosed
switchgear, unit substations, transformers, pull boxes, connection boxes,
and other similar associated equipment
shall be marked with appropriate caution signs. If equipment is exposed to
physical damage from vehicular traffic,
guards shall be provided to prevent
such damage. Ventilating or similar
openings in metal-enclosed equipment
shall be designed so that foreign objects inserted through these openings
will be deflected from energized parts.
(3) Workspace about equipment. Sufficient space shall be provided and maintained about electric equipment to permit ready and safe operation and maintenance of such equipment. Where energized parts are exposed, the minimum clear workspace shall not be less
than 6 feet 6 inches (1.98 m) high (measured vertically from the floor or platform), or less than 3 feet (914 mm) wide
(measured parallel to the equipment).
The depth shall be as required in Table
K–2. The workspace shall be adequate
to permit at least a 90-degree opening
of doors or hinged panels.
(i) Working space. The minimum clear
working space in front of electric
equipment such as switchboards, control panels, switches, circuit breakers,
motor controllers, relays, and similar
equipment shall not be less than specified in Table K–2 unless otherwise specified in this subpart. Distances shall be
measured from the live parts if they
are exposed, or from the enclosure
front or opening if the live parts are
enclosed. However, working space is
not required in back of equipment such
as deadfront switchboards or control
assemblies where there are no renewable or adjustable parts (such as fuses
or switches) on the back and where all
connections are accessible from locations other than the back. Where rear
access is required to work on de-energized parts on the back of enclosed
equipment, a minimum working space
of 30 inches (762 mm) horizontally shall
be provided.
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Occupational Safety and Health Admin., Labor
TABLE K–2—MINIMUM DEPTH OF CLEAR WORKING SPACE IN FRONT OF ELECTRIC EQUIPMENT
Nominal voltage to ground
(a)
(b)
(c)
Feet 2
Feet 2
Feet 2
3
4
5
6
8
4
5
6
8
10
5
6
9
10
12
1Conditions (a), (b), and (c) are as follows: (a) Exposed live
parts on one side and no live or grounded parts on the other
side of the working space, or exposed live parts on both sides
effectively guarded by insulating materials. Insulated wire or
insulated busbars operating at not over 300 volts are not considered live parts. (b) Exposed live parts on one side and
grounded parts on the other side. Walls constructed of concrete, brick, or tile are considered to be grounded surfaces.
(c) Exposed live parts on both sides of the workspace [not
guarded as provided in Condition (a)] with the operator between.
2 NOTE: For SI units: one foot=0.3048 m.
(ii) Lighting outlets and points of control. The lighting outlets shall be so arranged that persons changing lamps or
making repairs on the lighting system
will not be endangered by live parts or
other equipment. The points of control
shall be so located that persons are not
likely to come in contact with any live
part or moving part of the equipment
while turning on the lights.
(iii) Elevation of unguarded live parts.
Unguarded live parts above working
space shall be maintained at elevations
not less than specified in Table K–3.
TABLE K–3—ELEVATION OF UNGUARDED
ENERGIZED PARTS ABOVE WORKING SPACE
Nominal voltage between
phases
601–7,500 ..............................
7,501–35,000 .........................
Over 35kV ..............................
1 NOTE:
cent to such entrance, they shall be
guarded.
[51 FR 25318, July 11, 1986, as amended at 61
FR 5510, Feb. 13, 1996]
Conditions 1
601 to 2,500 ..............................
2,501 to 9,000 ...........................
9,001 to 25,000 .........................
25,001 to 75 kV .........................
Above 75kV ...............................
§ 1926.404
Minimum elevation
8 feet 6 inches. 1
9 feet.
9 feet+0.37 inches per kV
above 35kV.
For SI units: one inch=25.4 mm; one foot=0.3048
m.
(4) Entrance and access to workspace.
At least one entrance not less than 24
inches (610 mm) wide and 6 feet 6 inches
(1.98 m) high shall be provided to give
access to the working space about electric equipment. On switchboard and
control panels exceeding 48 inches (1.22
m) in width, there shall be one entrance at each end of such board where
practicable. Where bare energized parts
at any voltage or insulated energized
parts above 600 volts are located adja-
§ 1926.404 Wiring design and protection.
(a) Use and identification of grounded
and grounding conductors—(1) Identification of conductors. A conductor used as
a grounded conductor shall be identifiable and distinguishable from all other
conductors. A conductor used as an
equipment grounding conductor shall
be identifiable and distinguishable
from all other conductors.
(2) Polarity of connections. No grounded conductor shall be attached to any
terminal or lead so as to reverse designated polarity.
(3) Use of grounding terminals and devices. A grounding terminal or grounding-type device on a receptacle, cord
connector, or attachment plug shall
not be used for purposes other than
grounding.
(b) Branch circuits—(1) Ground-fault
protection—(i) General. The employer
shall use either ground fault circuit interrupters as specified in paragraph
(b)(1)(ii) of this section or an assured
equipment grounding conductor program
as
specified
in
paragraph
(b)(1)(iii) of this section to protect employees on construction sites. These requirements are in addition to any
other requirements for equipment
grounding conductors.
(ii) Ground-fault circuit interrupters.
All 120-volt, single-phase, 15- and 20ampere receptacle outlets on construction sites, which are not a part of the
permanent wiring of the building or
structure and which are in use by employees, shall have approved groundfault circuit interrupters for personnel
protection. Receptacles on a two-wire,
single-phase
portable
or
vehiclemounted generator rated not more
than 5kW, where the circuit conductors
of the generator are insulated from the
generator frame and all other grounded
surfaces, need not be protected with
ground-fault circuit interrupters.
(iii) Assured equipment grounding conductor program. The employer shall establish and implement an assured
equipment grounding conductor program on construction sites covering all
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§ 1926.404
29 CFR Ch. XVII (7–1–14 Edition)
cord sets, receptacles which are not a
part of the building or structure, and
equipment connected by cord and plug
which are available for use or used by
employees. This program shall comply
with the following minimum requirements:
(A) A written description of the program, including the specific procedures
adopted by the employer, shall be
available at the jobsite for inspection
and copying by the Assistant Secretary
and any affected employee.
(B) The employer shall designate one
or more competent persons (as defined
in § 1926.32(f)) to implement the program.
(C) Each cord set, attachment cap,
plug and receptacle of cord sets, and
any equipment connected by cord and
plug, except cord sets and receptacles
which are fixed and not exposed to
damage, shall be visually inspected before each day’s use for external defects,
such as deformed or missing pins or insulation damage, and for indications of
possible internal damage. Equipment
found damaged or defective shall not
be used until repaired.
(D) The following tests shall be performed on all cord sets, receptacles
which are not a part of the permanent
wiring of the building or structure, and
cord- and plug-connected equipment required to be grounded:
(1) All equipment grounding conductors shall be tested for continuity and
shall be electrically continuous.
(2) Each receptacle and attachment
cap or plug shall be tested for correct
attachment of the equipment grounding conductor. The equipment grounding conductor shall be connected to its
proper terminal.
(E) All required tests shall be performed:
(1) Before first use;
(2) Before equipment is returned to
service following any repairs;
(3) Before equipment is used after
any incident which can be reasonably
suspected to have caused damage (for
example, when a cord set is run over);
and
(4) At intervals not to exceed 3
months, except that cord sets and receptacles which are fixed and not exposed to damage shall be tested at intervals not exceeding 6 months.
(F) The employer shall not make
available or permit the use by employees of any equipment which has not
met the requirements of this paragraph
(b)(1)(iii) of this section.
(G) Tests performed as required in
this paragraph shall be recorded. This
test record shall identify each receptacle, cord set, and cord- and plug-connected equipment that passed the test
and shall indicate the last date it was
tested or the interval for which it was
tested. This record shall be kept by
means of logs, color coding, or other effective means and shall be maintained
until replaced by a more current
record. The record shall be made available on the jobsite for inspection by
the Assistant Secretary and any affected employee.
(2) Outlet devices. Outlet devices shall
have an ampere rating not less than
the load to be served and shall comply
with the following:
(i) Single receptacles. A single receptacle installed on an individual branch
circuit shall have an ampere rating of
not less than that of the branch circuit.
(ii) Two or more receptacles. Where
connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform
to the values listed in Table K–4.
(iii) Receptacles used for the connection
of motors. The rating of an attachment
plug or receptacle used for cord- and
plug-connection of a motor to a branch
circuit shall not exceed 15 amperes at
125 volts or 10 amperes at 250 volts if
individual overload protection is omitted.
TABLE K–4—RECEPTACLE RATINGS FOR
VARIOUS SIZE CIRCUITS
Circuit rating amperes
15
20
30
40
50
...................................................................
...................................................................
...................................................................
...................................................................
...................................................................
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Not over 15.
15 or 20.
30.
40 or 50.
50.
(c) Outside conductors and lamps—(1)
600 volts, nominal, or less. Paragraphs
(c)(1)(i) through (c)(1)(iv) of this section apply to branch circuit, feeder,
and service conductors rated 600 volts,
nominal, or less and run outdoors as
open conductors.
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Occupational Safety and Health Admin., Labor
(i) Conductors on poles. Conductors
supported on poles shall provide a horizontal climbing space not less than the
following:
(A) Power conductors below communication conductors—30 inches (762
mm) .
(B) Power conductors alone or above
communication conductors: 300 volts or
less—24 inches (610 mm); more than 300
volts—30 inches (762 mm).
(C) Communication conductors below
power conductors: with power conductors 300 volts or less—24 inches (610
mm); more than 300 volts—30 inches
(762 mm).
(ii) Clearance from ground. Open conductors shall conform to the following
minimum clearances:
(A) 10 feet (3.05 m)—above finished
grade, sidewalks, or from any platform
or projection from which they might be
reached.
(B) 12 feet (3.66 m)—over areas subject to vehicular traffic other than
truck traffic.
(C) 15 feet (4.57 m)—over areas other
than those specified in paragraph
(c)(1)(ii)(D) of this section that are subject to truck traffic.
(D) 18 feet (5.49 m)—over public
streets, alleys, roads, and driveways.
(iii) Clearance from building openings.
Conductors shall have a clearance of at
least 3 feet (914 mm) from windows,
doors, fire escapes, or similar locations. Conductors run above the top
level of a window are considered to be
out of reach from that window and,
therefore, do not have to be 3 feet (914
mm) away.
(iv) Clearance over roofs. Conductors
above roof space accessible to employees on foot shall have a clearance from
the highest point of the roof surface of
not less than 8 feet (2.44 m) vertical
clearance for insulated conductors, not
less than 10 feet (3.05 m) vertical or diagonal clearance for covered conductors, and not less than 15 feet (4.57 m)
for bare conductors, except that:
(A) Where the roof space is also accessible to vehicular traffic, the
vertical clearance shall not be less
than 18 feet (5.49 m), or
(B) Where the roof space is not normally accessible to employees on foot,
fully insulated conductors shall have a
§ 1926.404
vertical or diagonal clearance of not
less than 3 feet (914 mm), or
(C) Where the voltage between conductors is 300 volts or less and the roof
has a slope of not less than 4 inches (102
mm) in 12 inches (305 mm), the clearance from roofs shall be at least 3 feet
(914 mm), or
(D) Where the voltage between conductors is 300 volts or less and the conductors do not pass over more than 4
feet (1.22 m) of the overhang portion of
the roof and they are terminated at a
through-the-roof raceway or support,
the clearance from roofs shall be at
least 18 inches (457 mm).
(2) Location of outdoor lamps. Lamps
for outdoor lighting shall be located
below all live conductors, transformers, or other electric equipment,
unless such equipment is controlled by
a disconnecting means that can be
locked in the open position or unless
adequate clearances or other safeguards are provided for relamping operations.
(d) Services—(1) Disconnecting means—
(i) General. Means shall be provided to
disconnect all conductors in a building
or other structure from the service-entrance conductors. The disconnecting
means shall plainly indicate whether it
is in the open or closed position and
shall be installed at a readily accessible location nearest the point of entrance of the service-entrance conductors.
(ii) Simultaneous opening of poles.
Each service disconnecting means shall
simultaneously
disconnect
all
ungrounded conductors.
(2) Services over 600 volts, nominal. The
following
additional
requirements
apply to services over 600 volts, nominal.
(i) Guarding. Service-entrance conductors installed as open wires shall be
guarded to make them accessible only
to qualified persons.
(ii) Warning signs. Signs warning of
high voltage shall be posted where unauthorized employees might come in
contact with live parts.
(e) Overcurrent protection—(1) 600
volts, nominal, or less. The following requirements apply to overcurrent protection of circuits rated 600 volts,
nominal, or less.
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§ 1926.404
29 CFR Ch. XVII (7–1–14 Edition)
(i) Protection of conductors and equipment. Conductors and equipment shall
be protected from overcurrent in accordance with their ability to safely
conduct current. Conductors shall have
sufficient ampacity to carry the load.
(ii) Grounded conductors. Except for
motor-running overload protection,
overcurrent devices shall not interrupt
the continuity of the grounded conductor unless all conductors of the circuit are opened simultaneously.
(iii) Disconnection of fuses and thermal
cutouts. Except for devices provided for
current-limiting on the supply side of
the service disconnecting means, all
cartridge fuses which are accessible to
other than qualified persons and all
fuses and thermal cutouts on circuits
over 150 volts to ground shall be provided with disconnecting means. This
disconnecting means shall be installed
so that the fuse or thermal cutout can
be disconnected from its supply without disrupting service to equipment
and circuits unrelated to those protected by the overcurrent device.
(iv) Location in or on premises. Overcurrent devices shall be readily accessible. Overcurrent devices shall not be
located where they could create an employee safety hazard by being exposed
to physical damage or located in the
vicinity of easily ignitible material.
(v) Arcing or suddenly moving parts.
Fuses and circuit breakers shall be so
located or shielded that employees will
not be burned or otherwise injured by
their operation.
(vi) Circuit breakers—(A) Circuit
breakers shall clearly indicate whether
they are in the open (off) or closed (on)
position.
(B) Where circuit breaker handles on
switchboards are operated vertically
rather
than
horizontally
or
rotationally, the up position of the
handle shall be the closed (on) position.
(C) If used as switches in 120-volt, fluorescent lighting circuits, circuit
breakers shall be marked ‘‘SWD.’’
(2) Over 600 volts, nominal. Feeders
and branch circuits over 600 volts,
nominal, shall have short-circuit protection.
(f)
Grounding.
Paragraphs
(f)(1)
through (f)(11) of this section contain
grounding requirements for systems,
circuits, and equipment.
(1) Systems to be grounded. The following systems which supply premises
wiring shall be grounded:
(i) Three-wire DC systems. All 3-wire
DC systems shall have their neutral
conductor grounded.
(ii) Two-wire DC systems. Two-wire DC
systems operating at over 50 volts
through 300 volts between conductors
shall be grounded unless they are rectifier-derived from an AC system complying
with
paragraphs
(f)(1)(iii),
(f)(1)(iv), and (f)(1)(v) of this section.
(iii) AC circuits, less than 50 volts. AC
circuits of less than 50 volts shall be
grounded if they are installed as overhead conductors outside of buildings or
if they are supplied by transformers
and the transformer primary supply
system is ungrounded or exceeds 150
volts to ground.
(iv) AC systems, 50 volts to 1000 volts.
AC systems of 50 volts to 1000 volts
shall be grounded under any of the following conditions, unless exempted by
paragraph (f)(1)(v) of this section:
(A) If the system can be so grounded
that the maximum voltage to ground
on the ungrounded conductors does not
exceed 150 volts;
(B) If the system is nominally rated
480Y/277 volt, 3-phase, 4-wire in which
the neutral is used as a circuit conductor;
(C) If the system is nominally rated
240/120 volt, 3-phase, 4-wire in which
the midpoint of one phase is used as a
circuit conductor; or
(D) If a service conductor is
uninsulated.
(v) Exceptions. AC systems of 50 volts
to 1000 volts are not required to be
grounded if the system is separately
derived and is supplied by a transformer that has a primary voltage rating less than 1000 volts, provided all of
the following conditions are met:
(A) The system is used exclusively
for control circuits,
(B) The conditions of maintenance
and supervision assure that only qualified persons will service the installation,
(C) Continuity of control power is required, and
(D) Ground detectors are installed on
the control system.
(2) Separately derived systems. Where
paragraph (f)(1) of this section requires
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Occupational Safety and Health Admin., Labor
grounding of wiring systems whose
power is derived from generator, transformer, or converter windings and has
no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors
originating in another system, paragraph (f)(5) of this section shall also
apply.
(3) Portable and vehicle-mounted generators—(i) Portable generators. Under
the following conditions, the frame of a
portable generator need not be grounded and may serve as the grounding
electrode for a system supplied by the
generator:
(A) The generator supplies only
equipment mounted on the generator
and/or cord- and plug-connected equipment through receptacles mounted on
the generator, and
(B) The noncurrent-carrying metal
parts of equipment and the equipment
grounding conductor terminals of the
receptacles are bonded to the generator
frame.
(ii) Vehicle-mounted generators. Under
the following conditions the frame of a
vehicle may serve as the grounding
electrode for a system supplied by a
generator located on the vehicle:
(A) The frame of the generator is
bonded to the vehicle frame, and
(B) The generator supplies only
equipment located on the vehicle and/
or cord- and plug-connected equipment
through receptacles mounted on the
vehicle or on the generator, and
(C) The noncurrent-carrying metal
parts of equipment and the equipment
grounding conductor terminals of the
receptacles are bonded to the generator
frame, and
(D) The system complies with all
other provisions of this section.
(iii) Neutral conductor bonding. A neutral conductor shall be bonded to the
generator frame if the generator is a
component of a separately derived system. No other conductor need be bonded to the generator frame.
(4) Conductors to be grounded. For AC
premises wiring systems the identified
conductor shall be grounded.
(5) Grounding connections—(i) Grounded system. For a grounded system, a
grounding electrode conductor shall be
used to connect both the equipment
grounding conductor and the grounded
§ 1926.404
circuit conductor to the grounding
electrode. Both the equipment grounding conductor and the grounding electrode conductor shall be connected to
the grounded circuit conductor on the
supply side of the service disconnecting
means, or on the supply side of the system disconnecting means or overcurrent devices if the system is separately
derived.
(ii) Ungrounded systems. For an
ungrounded service-supplied system,
the equipment grounding conductor
shall be connected to the grounding
electrode conductor at the service
equipment. For an ungrounded separately derived system, the equipment
grounding conductor shall be connected to the grounding electrode conductor at, or ahead of, the system disconnecting means or overcurrent devices.
(6) Grounding path. The path to
ground from circuits, equipment, and
enclosures shall be permanent and continuous.
(7) Supports, enclosures, and equipment
to be grounded—(i) Supports and enclosures for conductors. Metal cable trays,
metal raceways, and metal enclosures
for conductors shall be grounded, except that:
(A) Metal enclosures such as sleeves
that are used to protect cable assemblies from physical damage need not be
grounded; and
(B) Metal enclosures for conductors
added to existing installations of open
wire, knob-and-tube wiring, and nonmetallic-sheathed cable need not be
grounded if all of the following conditions are met:
(1) Runs are less than 25 feet (7.62 m);
(2) Enclosures are free from probable
contact with ground, grounded metal,
metal laths, or other conductive materials; and
(3) Enclosures are guarded against
employee contact.
(ii) Service equipment enclosures. Metal
enclosures for service equipment shall
be grounded.
(iii) Fixed equipment. Exposed noncurrent-carrying metal parts of fixed
equipment which may become energized shall be grounded under any of
the following conditions:
(A) If within 8 feet (2.44 m) vertically
or 5 feet (1.52 m) horizontally of ground
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§ 1926.404
29 CFR Ch. XVII (7–1–14 Edition)
or grounded metal objects and subject
to employee contact.
(B) If located in a wet or damp location and subject to employee contact.
(C) If in electrical contact with
metal.
(D) If in a hazardous (classified) location.
(E) If supplied by a metal-clad,
metal-sheathed, or grounded metal
raceway wiring method.
(F) If equipment operates with any
terminal at over 150 volts to ground;
however, the following need not be
grounded:
(1) Enclosures for switches or circuit
breakers used for other than service
equipment and accessible to qualified
persons only;
(2) Metal frames of electrically heated appliances which are permanently
and effectively insulated from ground;
and
(3) The cases of distribution apparatus such as transformers and capacitors mounted on wooden poles at a
height exceeding 8 feet (2.44 m) above
ground or grade level.
(iv) Equipment connected by cord and
plug. Under any of the conditions described in paragraphs (f)(7)(iv)(A)
through (f)(7)(iv)(C) of this section, exposed noncurrent-carrying metal parts
of cord- and plug-connected equipment
which may become energized shall be
grounded:
(A) If in a hazardous (classified) location (see § 1926.407).
(B) If operated at over 150 volts to
ground, except for guarded motors and
metal frames of electrically heated appliances if the appliance frames are
permanently and effectively insulated
from ground.
(C) If the equipment is one of the
types
listed
in
paragraphs
(f)(7)(iv)(C)(1) through (f)(7)(iv)(C)(5) of
this section. However, even though the
equipment may be one of these types,
it need not be grounded if it is exempted by paragraph (f)(7)(iv)(C)(6).
(1) Hand held motor-operated tools;
(2) Cord- and plug-connected 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 and associated equipment;
(4) Tools likely to be used in wet and/
or conductive locations; and
(5) Portable hand lamps.
(6) Tools likely to be used in wet and/
or conductive locations need not be
grounded if supplied through an isolating transformer with an ungrounded
secondary of not over 50 volts. Listed
or labeled portable tools and appliances protected by a system of double
insulation, or its equivalent, need not
be grounded. If such a system is employed, the equipment shall be distinctively marked to indicate that the tool
or appliance utilizes a system of double
insulation.
(v) Nonelectrical equipment. The metal
parts of the following nonelectrical
equipment shall be grounded: Frames
and tracks of electrically operated
cranes; frames of nonelectrically driven elevator cars to which electric conductors are attached; hand-operated
metal shifting ropes or cables of electric elevators, and metal partitions,
grill work, and similar metal enclosures around equipment of over IkV between conductors.
(8) Methods of grounding equipment—
(i) With circuit conductors. Noncurrentcarrying metal parts of fixed equipment, if required to be grounded by
this subpart, shall be grounded by an
equipment grounding conductor which
is contained within the same raceway,
cable, or cord, or runs with or encloses
the circuit conductors. For DC circuits
only, the equipment grounding conductor may be run separately from the
circuit conductors.
(ii) Grounding conductor. A conductor
used for grounding fixed or movable
equipment shall have capacity to conduct safely any fault current which
may be imposed on it.
(iii) Equipment considered effectively
grounded. Electric equipment is considered to be effectively grounded if it is
secured to, and in electrical contact
with, a metal rack or structure that is
provided for its support and the metal
rack or structure is grounded by the
method specified for the noncurrentcarrying metal parts of fixed equipment in paragraph (f)(8)(i) of this section. Metal car frames supported by
metal hoisting cables attached to or
running over metal sheaves or drums of
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Occupational Safety and Health Admin., Labor
grounded elevator machines are also
considered to be effectively grounded.
(9) Bonding. If bonding conductors are
used to assure electrical continuity,
they shall have the capacity to conduct
any fault current which may be imposed.
(10) Made electrodes. If made electrodes are used, they shall be free from
nonconductive coatings, such as paint
or enamel; and, if practicable, they
shall be embedded below permanent
moisture level. A single electrode consisting of a rod, pipe or plate which has
a resistance to ground greater than 25
ohms shall be augmented by one additional electrode installed no closer
than 6 feet (1.83 m) to the first electrode.
(11) Grounding of systems and circuits
of 1000 volts and over (high voltage)—(i)
General. If high voltage systems are
grounded, they shall comply with all
applicable provisions of paragraphs
(f)(1) through (f)(10) of this section as
supplemented and modified by this
paragraph (f)(11).
(ii) Grounding of systems supplying
portable or mobile equipment. Systems
supplying portable or mobile high voltage equipment, other than substations
installed on a temporary basis, shall
comply with the following:
(A) Portable and mobile high voltage
equipment shall be supplied from a system having its neutral grounded
through an impedance. If a delta-connected high voltage system is used to
supply the equipment, a system neutral shall be derived.
(B)
Exposed
noncurrent-carrying
metal parts of portable and mobile
equipment shall be connected by an
equipment grounding conductor to the
point at which the system neutral impedance is grounded.
(C) Ground-fault detection and relaying shall be provided to automatically
de-energize any high voltage system
component which has developed a
ground fault. The continuity of the
equipment grounding conductor shall
be continuously monitored so as to deenergize automatically the high voltage feeder to the portable equipment
upon loss of continuity of the equipment grounding conductor.
(D) The grounding electrode to which
the portable or mobile equipment sys-
§ 1926.405
tem neutral impedance is connected
shall be isolated from and separated in
the ground by at least 20 feet (6.1 m)
from any other system or equipment
grounding electrode, and there shall be
no direct connection between the
grounding electrodes, such as buried
pipe, fence or like objects.
(iii) Grounding of equipment. All noncurrent-carrying metal parts of portable equipment and fixed equipment including
their
associated
fences,
housings, enclosures, and supporting
structures shall be grounded. However,
equipment which is guarded by location and isolated from ground need not
be grounded. Additionally, pole-mounted distribution apparatus at a height
exceeding 8 feet (2.44 m) above ground
or grade level need not be grounded.
[51 FR 25318, July 11, 1986, as amended at 54
FR 24334, June 7, 1989; 61 FR 5510, Feb. 13,
1996]
§ 1926.405 Wiring
methods,
components, and equipment for general
use.
(a) Wiring methods. The provisions of
this paragraph do not apply to conductors which form an integral part of
equipment such as motors, controllers,
motor control centers and like equipment.
(1) General requirements—(i) Electrical
continuity of metal raceways and enclosures. Metal raceways, cable armor, and
other metal enclosures for conductors
shall be metallically joined together
into a continuous electric conductor
and shall be so connected to all boxes,
fittings, and cabinets as to provide effective electrical continuity.
(ii) Wiring in ducts. No wiring systems
of any type shall be installed in ducts
used to transport dust, loose stock or
flammable vapors. No wiring system of
any type shall be installed in any duct
used for vapor removal or in any shaft
containing only such ducts.
(2) Temporary wiring—(i) Scope. The
provisions of paragraph (a)(2) of this
section apply to temporary electrical
power and lighting wiring methods
which may be of a class less than would
be required for a permanent installation. Except as specifically modified in
paragraph (a)(2) of this section, all
other requirements of this subpart for
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§ 1926.405
29 CFR Ch. XVII (7–1–14 Edition)
permanent wiring shall apply to temporary wiring installations. Temporary
wiring shall be removed immediately
upon completion of construction or the
purpose for which the wiring was installed.
(ii) General requirements for temporary
wiring—(A) Feeders shall originate in a
distribution center. The conductors
shall be run as multiconductor cord or
cable assemblies or within raceways;
or, where not subject to physical damage, they may be run as open conductors on insulators not more than 10 feet
(3.05 m) apart.
(B) Branch circuits shall originate in
a power outlet or panelboard. Conductors shall be run as multiconductor
cord or cable assemblies or open conductors, or shall be run in raceways.
All conductors shall be protected by
overcurrent devices at their ampacity.
Runs of open conductors shall be located where the conductors will not be
subject to physical damage, and the
conductors shall be fastened at intervals not exceeding 10 feet (3.05 m). No
branch-circuit conductors shall be laid
on the floor. Each branch circuit that
supplies receptacles or fixed equipment
shall contain a separate equipment
grounding conductor if the branch circuit is run as open conductors.
(C) Receptacles shall be of the
grounding type. Unless installed in a
complete
metallic
raceway,
each
branch circuit shall contain a separate
equipment grounding conductor, and
all receptacles shall be electrically
connected to the grounding conductor.
Receptacles for uses other than temporary lighting shall not be installed
on branch circuits which supply temporary lighting. Receptacles shall not
be connected to the same ungrounded
conductor of multiwire circuits which
supply temporary lighting.
(D) Disconnecting switches or plug
connectors shall be installed to permit
the disconnection of all ungrounded
conductors of each temporary circuit.
(E) All lamps for general illumination shall be protected from accidental
contact or breakage. Metal-case sockets shall be grounded.
(F) Temporary lights shall not be
suspended by their electric cords unless
cords and lights are designed for this
means of suspension.
(G) Portable electric lighting used in
wet and/or other conductive locations,
as for example, drums, tanks, and vessels, shall be operated at 12 volts or
less. However, 120-volt lights may be
used if protected by a ground-fault circuit interrupter.
(H) A box shall be used wherever a
change is made to a raceway system or
a cable system which is metal clad or
metal sheathed.
(I) Flexible cords and cables shall be
protected from damage. Sharp corners
and projections shall be avoided. Flexible cords and cables may pass through
doorways or other pinch points, if protection is provided to avoid damage.
(J) Extension cord sets used with
portable electric tools and appliances
shall be of three-wire type and shall be
designed for hard or extra-hard usage.
Flexible cords used with temporary and
portable lights shall be designed for
hard or extra-hard usage.
NOTE: The National Electrical Code, ANSI/
NFPA 70, in Article 400, Table 400–4, lists
various types of flexible cords, some of which
are noted as being designed for hard or extrahard usage. Examples of these types of flexible cords include hard service cord (types S,
ST, SO, STO) and junior hard service cord
(types SJ, SJO, SJT, SJTO).
(iii) Guarding. For temporary wiring
over 600 volts, nominal, fencing, barriers, or other effective means shall be
provided to prevent access of other
than authorized and qualified personnel.
(b) Cabinets, boxes, and fittings—(1)
Conductors entering boxes, cabinets, or
fittings. Conductors entering boxes,
cabinets, or fittings shall be protected
from abrasion, and openings through
which conductors enter shall be effectively closed. Unused openings in cabinets, boxes, and fittings shall also be
effectively closed.
(2) Covers and canopies. All pull boxes,
junction boxes, and fittings shall be
provided with covers. If metal covers
are used, they shall be grounded. In energized installations each outlet box
shall have a cover, faceplate, or fixture
canopy. Covers of outlet boxes having
holes through which flexible cord pendants pass shall be provided with bushings designed for the purpose or shall
have smooth, well-rounded surfaces on
which the cords may bear.
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Occupational Safety and Health Admin., Labor
(3) Pull and junction boxes for systems
over 600 volts, nominal. In addition to
other requirements in this section for
pull and junction boxes, the following
shall apply to these boxes for systems
over 600 volts, nominal:
(i) Complete enclosure. Boxes shall
provide a complete enclosure for the
contained conductors or cables.
(ii) Covers. Boxes shall be closed by
covers securely fastened in place. Underground box covers that weigh over
100 pounds (43.6 kg) meet this requirement. Covers for boxes shall be permanently marked ‘‘HIGH VOLTAGE.’’
The marking shall be on the outside of
the box cover and shall be readily visible and legible.
(c) Knife switches. Single-throw knife
switches shall be so connected that the
blades are dead when the switch is in
the open position. Single-throw knife
switches shall be so placed that gravity
will not tend to close them. Singlethrow knife switches approved for use
in the inverted position shall be provided with a locking device that will
ensure that the blades remain in the
open position when so set. Doublethrow knife switches may be mounted
so that the throw will be either
vertical or horizontal. However, if the
throw is vertical, a locking device shall
be provided to ensure that the blades
remain in the open position when so
set.
(d) Switchboards and panelboards.
Switchboards that have any exposed
live parts shall be located in permanently dry locations and accessible
only to qualified persons. Panelboards
shall be mounted in cabinets, cutout
boxes, or enclosures designed for the
purpose and shall be dead front. However, panelboards other than the dead
front externally-operable type are permitted where accessible only to qualified persons. Exposed blades of knife
switches shall be dead when open.
(e) Enclosures for damp or wet locations—(1) Cabinets, fittings, and boxes.
Cabinets, cutout boxes, fittings, boxes,
and panelboard enclosures in damp or
wet locations shall be installed so as to
prevent moisture or water from entering and accumulating within the enclosures. In wet locations the enclosures
shall be weatherproof.
§ 1926.405
(2) Switches and circuit breakers.
Switches, circuit breakers, and switchboards installed in wet locations shall
be enclosed in weatherproof enclosures.
(f) Conductors for general wiring. All
conductors used for general wiring
shall be insulated unless otherwise permitted in this subpart. The conductor
insulation shall be of a type that is
suitable for the voltage, operating temperature, and location of use. Insulated
conductors shall be distinguishable by
appropriate color or other means as
being
grounded
conductors,
ungrounded conductors, or equipment
grounding conductors.
(g) Flexible cords and cables—(1) Use of
flexible cords and cables—(i) Permitted
uses. Flexible cords and cables shall be
suitable for conditions of use and location. Flexible cords and cables shall be
used only for:
(A) Pendants;
(B) Wiring of fixtures;
(C) Connection of portable lamps or
appliances;
(D) Elevator cables;
(E) Wiring of cranes and hoists;
(F) Connection of stationary equipment to facilitate their frequent interchange;
(G) Prevention of the transmission of
noise or vibration; or
(H) Appliances where the fastening
means and mechanical connections are
designed to permit removal for maintenance and repair.
(ii) Attachment plugs for cords. If used
as permitted in paragraphs (g)(1)(i)(C),
(g)(1)(i)(F), or (g)(1)(i)(H) of this section, the flexible cord shall be equipped
with an attachment plug and shall be
energized from a receptacle outlet.
(iii) Prohibited uses. Unless necessary
for a use permitted in paragraph
(g)(1)(i) of this section, flexible cords
and cables shall not be used:
(A) As a substitute for the fixed wiring of a structure;
(B) Where run through holes in walls,
ceilings, or floors;
(C) Where run through doorways,
windows, or similar openings, except as
permitted in paragraph (a)(2)(ii)(1) of
this section;
(D) Where attached to building surfaces; or
(E) Where concealed behind building
walls, ceilings, or floors.
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§ 1926.405
29 CFR Ch. XVII (7–1–14 Edition)
(2) Identification, splices, and terminations—(i) Identification. A conductor
of a flexible cord or cable that is used
as a grounded conductor or an equipment grounding conductor shall be distinguishable from other conductors.
(ii) Marking. Type SJ, SJO, SJT,
SJTO, S, SO, ST, and STO cords shall
not be used unless durably marked on
the surface with the type designation,
size, and number of conductors.
(iii) Splices. Flexible cords shall be
used only in continuous lengths without splice or tap. Hard service flexible
cords No. 12 or larger may be repaired
if spliced so that the splice retains the
insulation, outer sheath properties,
and usage characteristics of the cord
being spliced.
(iv) Strain relief. Flexible cords shall
be connected to devices and fittings so
that strain relief is provided which will
prevent pull from being directly transmitted to joints or terminal screws.
(v) Cords passing through holes. Flexible cords and cables shall be protected
by bushings or fittings where passing
through holes in covers, outlet boxes,
or similar enclosures.
(h) Portable cables over 600 volts, nominal. Multiconductor portable cable for
use in supplying power to portable or
mobile equipment at over 600 volts,
nominal, shall consist of No. 8 or larger
conductors employing flexible stranding. Cables operated at over 2000 volts
shall be shielded for the purpose of confining the voltage stresses to the insulation. Grounding conductors shall be
provided. Connectors for these cables
shall be of a locking type with provisions to prevent their opening or closing while energized. Strain relief shall
be provided at connections and terminations. Portable cables shall not be
operated with splices unless the splices
are of the permanent molded, vulcanized, or other equivalent type. Termination enclosures shall be marked with
a high voltage hazard warning, and terminations shall be accessible only to
authorized and qualified personnel.
(i) Fixture wires—(1) General. Fixture
wires shall be suitable for the voltage,
temperature, and location of use. A fixture wire which is used as a grounded
conductor shall be identified.
(2) Uses permitted. Fixture wires may
be used:
(i) For installation in lighting, fixtures and in similar equipment where
enclosed or protected and not subject
to bending or twisting in use; or
(ii) For connecting lighting fixtures
to the branch-circuit conductors supplying the fixtures.
(3) Uses not permitted. Fixture wires
shall not be used as branch-circuit conductors except as permitted for Class 1
power-limited circuits.
(j) Equipment for general use—(1)
Lighting fixtures, lampholders, lamps,
and receptacles—(i) Live parts. Fixtures,
lampholders, lamps, rosettes, and receptacles shall have no live parts normally exposed to employee contact.
However,
rosettes
and
cleat-type
lampholders and receptacles located at
least 8 feet (2.44 m) above the floor may
have exposed parts.
(ii) Support. Fixtures, lampholders,
rosettes, and receptacles shall be securely supported. A fixture that weighs
more than 6 pounds (2.72 kg) or exceeds
16 inches (406 mm) in any dimension
shall not be supported by the screw
shell of a lampholder.
(iii) Portable lamps. Portable lamps
shall be wired with flexible cord and an
attachment plug of the polarized or
grounding type. If the portable lamp
uses an Edison-based lampholder, the
grounded conductor shall be identified
and attached to the screw shell and the
identified blade of the attachment
plug. In addition, portable handlamps
shall comply with the following:
(A)
Metal
shell,
paperlined
lampholders shall not be used;
(B) Handlamps shall be equipped with
a handle of molded composition or
other insulating material;
(C) Handlamps shall be equipped with
a substantial guard attached to the
lampholder or handle;
(D) Metallic guards shall be grounded
by the means of an equipment grounding conductor run within the power
supply cord.
(iv) Lampholders. Lampholders of the
screw-shell type shall be installed for
use as lampholders only. Lampholders
installed in wet or damp locations shall
be of the weatherproof type.
(v) Fixtures. Fixtures installed in wet
or damp locations shall be identified
for the purpose and shall be installed
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Occupational Safety and Health Admin., Labor
so that water cannot enter or accumulate in wireways, lampholders, or other
electrical parts.
(2) Receptacles, cord connectors, and attachment plugs (caps)—(i) Configuration.
Receptacles, cord connectors, and attachment plugs shall be constructed so
that no receptacle or cord connector
will accept an attachment plug with a
different voltage or current rating than
that for which the device is intended.
However, a 20-ampere T-slot receptacle
or cord connector may accept a 15-ampere attachment plug of the same voltage rating. Receptacles connected to
circuits having different voltages, frequencies, or types of current (ac or dc)
on the same premises shall be of such
design that the attachment plugs used
on these circuits are not interchangeable.
(ii) Damp and wet locations. A receptacle installed in a wet or damp location shall be designed for the location.
(3) Appliances—(i) Live parts. Appliances, other than those in which the
current-carrying parts at high temperatures are necessarily exposed, shall
have no live parts normally exposed to
employee contact.
(ii) Disconnecting means. A means
shall be provided to disconnect each
appliance.
(iii) Rating. Each appliance shall be
marked with its rating in volts and
amperes or volts and watts.
(4) Motors. This paragraph applies to
motors, motor circuits, and controllers.
(i) In sight from. If specified that one
piece of equipment shall be ‘‘in sight
from’’ another piece of equipment, one
shall be visible and not more than 50
feet (15.2 m) from the other.
(ii) Disconnecting means—(A) A disconnecting means shall be located in
sight from the controller location. The
controller disconnecting means for
motor branch circuits over 600 volts,
nominal, may be out of sight of the
controller, if the controller is marked
with a warning label giving the location and identification of the disconnecting means which is to be locked
in the open position.
(B) The disconnecting means shall
disconnect the motor and the controller from all ungrounded supply con-
§ 1926.405
ductors and shall be so designed that
no pole can be operated independently.
(C) If a motor and the driven machinery are not in sight from the controller
location, the installation shall comply
with one of the following conditions:
(1) The controller disconnecting
means shall be capable of being locked
in the open position.
(2) A manually operable switch that
will disconnect the motor from its
source of supply shall be placed in
sight from the motor location.
(D) The disconnecting means shall
plainly indicate whether it is in the
open (off) or closed (on) position.
(E) The disconnecting means shall be
readily accessible. If more than one
disconnect is provided for the same
equipment, only one need be readily
accessible.
(F) An individual disconnecting
means shall be provided for each
motor, but a single disconnecting
means may be used for a group of motors under any one of the following
conditions:
(1) If a number of motors drive special parts of a single machine or piece
of apparatus, such as a metal or woodworking machine, crane, or hoist;
(2) If a group of motors is under the
protection of one set of branch-circuit
protective devices; or
(3) If a group of motors is in a single
room in sight from the location of the
disconnecting means.
(iii) Motor overload, short-circuit, and
ground-fault protection. Motors, motorcontrol apparatus, and motor branchcircuit conductors shall be protected
against overheating due to motor overloads or failure to start, and against
short-circuits or ground faults. These
provisions do not require overload protection that will stop a motor where a
shutdown is likely to introduce additional or increased hazards, as in the
case of fire pumps, or where continued
operation of a motor is necessary for a
safe shutdown of equipment or process
and motor overload sensing devices are
connected to a supervised alarm.
(iv) Protection of live parts—all
voltages—(A) Stationary motors having
commutators, collectors, and brush
rigging located inside of motor end
brackets and not conductively connected to supply circuits operating at
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§ 1926.406
29 CFR Ch. XVII (7–1–14 Edition)
more than 150 volts to ground need not
have such parts guarded. Exposed live
parts of motors and controllers operating at 50 volts or more between terminals shall be guarded against accidental contact by any of the following:
(1) By installation in a room or enclosure that is accessible only to qualified persons;
(2) By installation on a balcony, gallery, or platform, so elevated and arranged as to exclude unqualified persons; or
(3) By elevation 8 feet (2.44 m) or
more above the floor.
(B) Where live parts of motors or controllers operating at over 150 volts to
ground are guarded against accidental
contact only by location, and where adjustment or other attendance may be
necessary during the operation of the
apparatus, insulating mats or platforms shall be provided so that the attendant cannot readily touch live parts
unless standing on the mats or platforms.
(5) Transformers—(i) Application. The
following paragraphs cover the installation of all transformers, except:
(A) Current transformers;
(B) Dry-type transformers installed
as a component part of other apparatus;
(C) Transformers which are an integral part of an X-ray, high frequency,
or electrostatic-coating apparatus;
(D) Transformers used with Class 2
and Class 3 circuits, sign and outline
lighting, electric discharge lighting,
and power-limited fire-protective signaling circuits.
(ii) Operating voltage. The operating
voltage of exposed live parts of transformer installations shall be indicated
by warning signs or visible markings
on the equipment or structure.
(iii) Transformers over 35 kV. Drytype, high fire point liquid-insulated,
and askarel-insulated transformers installed indoors and rated over 35 kV
shall be in a vault.
(iv) Oil-insulated transformers. If they
present a fire hazard to employees, oilinsulated transformers installed indoors shall be in a vault.
(v) Fire protection. Combustible material, combustible buildings and parts of
buildings, fire escapes, and door and
window openings shall be safeguarded
from fires which may originate in oilinsulated transformers attached to or
adjacent to a building or combustible
material.
(vi) Transformer vaults. Transformer
vaults shall be constructed so as to
contain fire and combustible liquids
within the vault and to prevent unauthorized access. Locks and latches
shall be so arranged that a vault door
can be readily opened from the inside.
(vii) Pipes and ducts. Any pipe or duct
system foreign to the vault installation shall not enter or pass through a
transformer vault.
(viii) Material storage. Materials shall
not be stored in transformer vaults.
(6) Capacitors—(i) Drainage of stored
charge. All capacitors, except surge capacitors or capacitors included as a
component part of other apparatus,
shall be provided with an automatic
means of draining the stored charge
and maintaining the discharged state
after the capacitor is disconnected
from its source of supply.
(ii) Over 600 volts. Capacitors rated
over 600 volts, nominal, shall comply
with the following additional requirements:
(A) Isolating or disconnecting switches (with no interrupting rating) shall
be interlocked with the load interrupting device or shall be provided
with prominently displayed caution
signs to prevent switching load current.
(B) For series capacitors the proper
switching shall be assured by use of at
least one of the following:
(1) Mechanically sequenced isolating
and bypass switches,
(2) Interlocks, or
(3) Switching procedure prominently
displayed at the switching location.
[51 FR 25318, July 11, 1986, as amended at 61
FR 5510, Feb. 13, 1996]
§ 1926.406 Specific purpose equipment
and installations.
(a) Cranes and hoists. This paragraph
applies to the installation of electric
equipment and wiring used in connection with cranes, monorail hoists,
hoists, and all runways.
(1) Disconnecting means—(i) Runway
conductor disconnecting means. A readily
accessible disconnecting means shall
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Occupational Safety and Health Admin., Labor
be provided between the runway contact conductors and the power supply.
(ii) Disconnecting means for cranes and
monorail hoists. A disconnecting means,
capable of being locked in the open position, shall be provided in the leads
from the runway contact conductors or
other power supply on any crane or
monorail hoist.
(A) If this additional disconnecting
means is not readily accessible from
the crane or monorail hoist operating
station, means shall be provided at the
operating station to open the power
circuit to all motors of the crane or
monorail hoist.
(B) The additional disconnect may be
omitted if a monorail hoist or handpropelled crane bridge installation
meets all of the following:
(1) The unit is floor controlled;
(2) The unit is within view of the
power supply disconnecting means; and
(3) No fixed work platform has been
provided for servicing the unit.
(2) Control. A limit switch or other
device shall be provided to prevent the
load block from passing the safe upper
limit of travel of any hoisting mechanism.
(3) Clearance. The dimension of the
working space in the direction of access to live parts which may require
examination, adjustment, servicing, or
maintenance while alive shall be a
minimum of 2 feet 6 inches (762 mm).
Where controls are enclosed in cabinets, the door(s) shall open at least 90
degrees or be removable, or the installation shall provide equivalent access.
(4) Grounding. All exposed metal
parts of cranes, monorail hoists, hoists
and accessories including pendant controls shall be metallically joined together into a continuous electrical conductor so that the entire crane or hoist
will be grounded in accordance with
§ 1926.404(f). Moving parts, other than
removable accessories or attachments,
having metal-to-metal bearing surfaces
shall be considered to be electrically
connected to each other through the
bearing surfaces for grounding purposes. The trolley frame and bridge
frame shall be considered as electrically grounded through the bridge
and trolley wheels and its respective
tracks unless conditions such as paint
or other insulating materials prevent
§ 1926.406
reliable metal-to-metal contact. In this
case a separate bonding conductor
shall be provided.
(b) Elevators, escalators, and moving
walks—(1) Disconnecting means. Elevators, escalators, and moving walks
shall have a single means for disconnecting all ungrounded main power
supply conductors for each unit.
(2) Control panels. If control panels
are not located in the same space as
the drive machine, they shall be located in cabinets with doors or panels
capable of being locked closed.
(c)
Electric
welders—disconnecting
means—(1) Motor-generator, AC transformer, and DC rectifier arc welders. A
disconnecting means shall be provided
in the supply circuit for each motorgenerator arc welder, and for each AC
transformer and DC rectifier arc welder
which is not equipped with a disconnect mounted as an integral part of
the welder.
(2) Resistance welders. A switch or circuit breaker shall be provided by which
each resistance welder and its control
equipment can be isolated from the
supply circuit. The ampere rating of
this disconnecting means shall not be
less
than
the
supply
conductor
ampacity.
(d) X-Ray equipment—(1) Disconnecting
means—(i) General. A disconnecting
means shall be provided in the supply
circuit. The disconnecting means shall
be operable from a location readily accessible from the X-ray control. For
equipment connected to a 120-volt
branch circuit of 30 amperes or less, a
grounding-type attachment plug cap
and receptacle of proper rating may
serve as a disconnecting means.
(ii) More than one piece of equipment.
If more than one piece of equipment is
operated from the same high-voltage
circuit, each piece or each group of
equipment as a unit shall be provided
with a high-voltage switch or equivalent disconnecting means. This disconnecting means shall be constructed,
enclosed, or located so as to avoid contact by employees with its live parts.
(2)
Control—Radiographic
and
fluoroscopic types. Radiographic and
fluoroscopic-type equipment shall be
effectively enclosed or shall have interlocks that deenergize the equipment
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§ 1926.407
29 CFR Ch. XVII (7–1–14 Edition)
automatically to prevent ready access
to live current-carrying parts.
§ 1926.407
tions.
Hazardous (classified) loca-
(a) Scope. This section sets forth 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 therein and the likelihood
that a flammable or combustible concentration or quantity is present. Each
room, section or area shall be considered individually in determining its
classification. These hazardous (classified) locations are assigned six designations as follows:
Class
Class
Class
Class
Class
Class
I, Division 1
I, Division 2
II, Division 1
II, Division 2
III, Division l
III, Division 2
For definitions of these locations see
§ 1926.449. All applicable requirements
in this subpart apply to all hazardous
(classified) locations, unless modified
by provisions of this section.
(b) Electrical installations. Equipment,
wiring methods, and installations of
equipment in hazardous (classified) locations shall be approved as intrinsically safe or approved for the hazardous (classified) location or safe for
the hazardous (classified) location. Requirements for each of these options
are as follows:
(1) Intrinsically safe. Equipment and
associated wiring approved as intrinsically safe is permitted in any hazardous (classified) location included in
its listing or labeling.
(2) Approved for the hazardous (classified) location—(i) General. Equipment
shall be approved not only for the class
of location but also for the ignitible or
combustible properties of the specific
gas, vapor, dust, or fiber that will be
present.
NOTE: NFPA 70, the National Electrical
Code, lists or defines hazardous gases, vapors, and dusts by ‘‘Groups’’ characterized by
their ignitible or combustible properties.
(ii) Marking. Equipment shall not be
used unless it is marked to show the
class, group, and operating tempera-
ture or temperature range, based on
operation in a 40-degree C ambient, for
which it is approved. The temperature
marking shall not exceed the ignition
temperature of the specific gas, vapor,
or dust to be encountered. However,
the following provisions modify this
marking requirement for specific
equipment:
(A) Equipment of the non-heat-producing type (such as junction boxes,
conduit, and fitting) and equipment of
the heat-producing type having a maximum temperature of not more than
100 degrees C (212 degrees F) need not
have a marked operating temperature
or temperature range.
(B) Fixed lighting fixtures marked
for use only in Class I, Division 2 locations need not be marked to indicate
the group.
(C) Fixed general-purpose equipment
in Class I locations, other than lighting
fixtures, which is acceptable for use in
Class I, Division 2 locations need not be
marked with the class, group, division,
or operating temperature.
(D) Fixed dust-tight equipment,
other than lighting fixtures, which is
acceptable for use in Class II, Division
2 and Class III locations need not be
marked with the class, group, division,
or operating temperature.
(3) Safe for the hazardous (classified)
location. Equipment which is safe for
the location shall be of a type and design which the employer demonstrates
will provide protection from the hazards arising from the combustibility
and flammability of vapors, liquids,
gases, dusts, or fibers.
NOTE: The National Electrical Code, NFPA
70, contains guidelines for determining the
type and design of equipment and installations which will meet this requirement. The
guidelines of this document address electric
wiring, equipment, and systems installed in
hazardous (classified) locations and contain
specific provisions for the following: wiring
methods, wiring connections, conductor insulation, flexible cords, sealing and drainage,
transformers, capacitors, switches, circuit
breakers, fuses, motor controllers, receptacles, attachment plugs, meters, relays, instruments, resistors, generators, motors,
lighting fixtures, storage battery charging
equipment, electric cranes, electric hoists
and similar equipment, utilization equipment, signaling systems, alarm systems, remote control systems, local loud speaker and
communication systems, ventilation piping,
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Occupational Safety and Health Admin., Labor
live parts, lightning surge protection, and
grounding. Compliance with these guidelines
will constitute one means, but not the only
means, of compliance with this paragraph.
(c) Conduits. All conduits shall be
threaded and shall be made wrenchtight. Where it is impractical to make
a threaded joint tight, a bonding jumper shall be utilized.
[51 FR 25318, July 11, 1986, as amended at 61
FR 5510, Feb. 13, 1996]
§ 1926.408
Special systems.
(a) Systems over 600 volts, nominal.
Paragraphs (a)(1) through (a)(4) of this
section contain general requirements
for all circuits and equipment operated
at over 600 volts.
(1) Wiring methods for fixed installations—(i) Above ground. Above-ground
conductors shall be installed in rigid
metal conduit, in intermediate metal
conduit, in cable trays, in cablebus, in
other suitable raceways, or as open
runs of metal-clad cable designed for
the use and purpose. However, open
runs of non-metallic-sheathed cable or
of bare conductors or busbars may be
installed in locations which are accessible only to qualified persons. Metallic
shielding components, such as tapes,
wires, or braids for conductors, shall be
grounded. Open runs of insulated wires
and cables having a bare lead sheath or
a braided outer covering shall be supported in a manner designed to prevent
physical damage to the braid or sheath.
(ii) Installations emerging from the
ground. Conductors emerging from the
ground shall be enclosed in raceways.
Raceways installed on poles shall be of
rigid metal conduit, intermediate
metal conduit, PVC schedule 80 or
equivalent extending from the ground
line up to a point 8 feet (2.44 m) above
finished grade. Conductors entering a
building shall be protected by an enclosure from the ground line to the point
of entrance. Metallic enclosures shall
be grounded.
(2) Interrupting and isolating devices—
(i) Circuit breakers. Circuit breakers located indoors shall consist of metal-enclosed or fire-resistant, cell-mounted
units. In locations accessible only to
qualified personnel, open mounting of
circuit breakers is permitted. A means
of indicating the open and closed posi-
§ 1926.408
tion of circuit breakers shall be provided.
(ii) Fused cutouts. Fused cutouts installed in buildings or transformer
vaults shall be of a type identified for
the purpose. They shall be readily accessible for fuse replacement.
(iii) Equipment isolating means. A
means shall be provided to completely
isolate equipment for inspection and
repairs. Isolating means which are not
designed to interrupt the load current
of
the
circuit
shall
be
either
interlocked with a circuit interrupter
or provided with a sign warning
against opening them under load.
(3) Mobile and portable equipment—(i)
Power cable connections to mobile machines. A metallic enclosure shall be
provided on the mobile machine for enclosing the terminals of the power
cable. The enclosure shall include provisions for a solid connection for the
ground wire(s) terminal to ground effectively the machine frame. The
method of cable termination used shall
prevent any strain or pull on the cable
from stressing the electrical connections. The enclosure shall have provision for locking so only authorized
qualified persons may open it and shall
be marked with a sign warning of the
presence of energized parts.
(ii) Guarding live parts. All energized
switching and control parts shall be enclosed in effectively grounded metal
cabinets or enclosures. Circuit breakers and protective equipment shall
have the operating means projecting
through the metal cabinet or enclosure
so these units can be reset without
locked doors being opened. Enclosures
and metal cabinets shall be locked so
that only authorized qualified persons
have access and shall be marked with a
sign warning of the presence of energized parts. Collector ring assemblies
on revolving-type machines (shovels,
draglines, etc.) shall be guarded.
(4) Tunnel installations—(i) Application. The provisions of this paragraph
apply to installation and use of highvoltage power distribution and utilization equipment which is associated
with tunnels and which is portable and/
or mobile, such as substations, trailers,
cars, mobile shovels, draglines, hoists,
drills, dredges, compressors, pumps,
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§ 1926.408
29 CFR Ch. XVII (7–1–14 Edition)
conveyors, and underground excavators.
(ii) Conductors. Conductors in tunnels
shall be installed in one or more of the
following:
(A) Metal conduit or other metal
raceway,
(B) Type MC cable, or
(C) Other suitable multiconductor
cable.
Conductors shall also be so located or
guarded as to protect them from physical damage. Multiconductor portable
cable may supply mobile equipment.
An equipment grounding conductor
shall be run with circuit conductors inside the metal raceway or inside the
multiconductor cable jacket. The
equipment grounding conductor may
be insulated or bare.
(iii) Guarding live parts. Bare terminals of transformers, switches, motor
controllers, and other equipment shall
be enclosed to prevent accidental contact with energized parts. Enclosures
for use in tunnels shall be drip-proof,
weatherproof, or submersible as required by the environmental conditions.
(iv) Disconnecting means. A disconnecting means that simultaneously
opens all ungrounded conductors shall
be installed at each transformer or
motor location.
(v) Grounding and bonding. All nonenergized metal parts of electric equipment and metal raceways and cable
sheaths shall be grounded and bonded
to all metal pipes and rails at the portal and at intervals not exceeding 1000
feet (305 m) throughout the tunnel.
(b) Class 1, Class 2, and Class 3 remote
control, signaling, and power-limited circuits—(1) Classification. Class 1, Class 2,
or Class 3 remote control, signaling, or
power-limited circuits are characterized by their usage and electrical power
limitation which differentiates them
from light and power circuits. These
circuits are classified in accordance
with their respective voltage and power
limitations as summarized in paragraphs (b)(1)(i) through (b)(1)(iii) of
this section.
(i) Class 1 circuits—(A) A Class 1
power-limited circuit is supplied from
a source having a rated output of not
more than 30 volts and 1000 volt-amperes.
(B) A Class 1 remote control circuit
or a Class 1 signaling circuit has a voltage which does not exceed 600 volts;
however, the power output of the
source need not be limited.
(ii) Class 2 and Class 3 circuits—(A)
Power for Class 2 and Class 3 circuits is
limited either inherently (in which no
overcurrent protection is required) or
by a combination of a power source and
overcurrent protection.
(B) The maximum circuit voltage is
150 volts AC or DC for a Class 2 inherently limited power source, and 100
volts AC or DC for a Class 3 inherently
limited power source.
(C) The maximum circuit voltage is
30 volts AC and 60 volts DC for a Class
2 power source limited by overcurrent
protection, and 150 volts AC or DC for
a Class 3 power source limited by overcurrent protection.
(iii) Application. The maximum circuit voltages in paragraphs (b)(1)(i) and
(b)(1)(ii) of this section apply to sinusoidal AC or continuous DC power
sources, and where wet contact occurrence is not likely.
(2) Marking. A Class 2 or Class 3
power supply unit shall not be used unless it is durably marked where plainly
visible to indicate the class of supply
and its electrical rating.
(c) Communications systems—(1) Scope.
These provisions for communication
systems apply to such systems as central-station-connected and non-central-station-connected telephone circuits, radio receiving and transmitting
equipment, and outside wiring for fire
and burglar alarm, and similar central
station systems. These installations
need not comply with the provisions of
§§ 1926.403 through 1926.408(b), except
§ 1926.404(c)(1)(ii) and § 1926.407.
(2) Protective devices—(i) Circuits exposed to power conductors. Communication circuits so located as to be exposed to accidental contact with light
or power conductors operating at over
300 volts shall have each circuit so exposed provided with an approved protector.
(ii) Antenna lead-ins. Each conductor
of a lead-in from an outdoor antenna
shall be provided with an antenna discharge unit or other means that will
drain static charges from the antenna
system.
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Occupational Safety and Health Admin., Labor
(3) Conductor location—(i) Outside of
buildings—(A) Receiving distribution
lead-in or aerial-drop cables attached
to buildings and lead-in conductors to
radio transmitters shall be so installed
as to avoid the possibility of accidental
contact with electric light or power
conductors.
(B) The clearance between lead-in
conductors and any lightning protection conductors shall not be less than 6
feet (1.83 m).
(ii) On poles. Where practicable, communication conductors on poles shall
be located below the light or power
conductors. Communications conductors shall not be attached to a crossarm that carries light or power conductors.
(iii) Inside of buildings. Indoor antennas, lead-ins, and other communication
conductors attached as open conductors to the inside of buildings shall be
located at least 2 inches (50.8 mm) from
conductors of any light or power or
Class 1 circuits unless a special and
equally protective method of conductor
separation is employed.
(4) Equipment location. Outdoor metal
structures supporting antennas, as well
as self-supporting antennas such as
vertical rods or dipole structures, shall
be located as far away from overhead
conductors of electric light and power
circuits of over 150 volts to ground as
necessary to avoid the possibility of
the antenna or structure falling into or
making accidental contact with such
circuits.
(5) Grounding—(i) Lead-in conductors.
If exposed to contact with electric
light or power conductors, the metal
sheath of aerial cables entering buildings shall be grounded or shall be interrupted close to the entrance to the
building by an insulating joint or
equivalent device. Where protective devices are used, they shall be grounded.
(ii) Antenna structures. Masts and
metal structures supporting antennas
shall be permanently and effectively
grounded without splice or connection
in the grounding conductor.
(iii) Equipment enclosures. Transmitters shall be enclosed in a metal frame
or grill or separated from the operating
space by a barrier, all metallic parts of
which are effectively connected to
ground. All external metal handles and
§ 1926.416
controls accessible to the operating
personnel shall be effectively grounded.
Unpowered equipment and enclosures
shall be considered grounded where
connected to an attached coaxial cable
with an effectively grounded metallic
shield.
[51 FR 25318, July 11, 1986, as amended at 61
FR 5510, Feb. 13, 1996]
§§ 1926.409–1926.415
[Reserved]
SAFETY-RELATED WORK PRACTICES
§ 1926.416
General requirements.
(a) Protection of employees—(1) No employer shall permit an employee to
work in such proximity to any part of
an electric power circuit that the employee could contact the electric power
circuit in the course of work, unless
the employee is protected against electric shock by deenergizing the circuit
and grounding it or by guarding it effectively by insulation or other means.
(2) In work areas where the exact location
of
underground
electric
powerlines is unknown, employees
using jack-hammers, bars, or other
hand tools which may contact a line
shall be provided with insulated protective gloves.
(3) Before work is begun the employer shall ascertain by inquiry or direct observation, or by instruments,
whether any part of an energized electric power circuit, exposed or concealed, is so located that the performance of the work may bring any person,
tool, or machine into physical or electrical contact with the electric power
circuit. The employer shall post and
maintain proper warning signs where
such a circuit exists. The employer
shall advise employees of the location
of such lines, the hazards involved, and
the protective measures to be taken.
(b) Passageways and open spaces—-(1)
Barriers or other means of guarding
shall be provided to ensure that workspace for electrical equipment will not
be used as a passageway during periods
when energized parts of electrical
equipment are exposed.
(2) Working spaces, walkways, and
similar locations shall be kept clear of
cords so as not to create a hazard to
employees.
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§ 1926.417
29 CFR Ch. XVII (7–1–14 Edition)
(c) Load ratings. In existing installations, no changes in circuit protection
shall be made to increase the load in
excess of the load rating of the circuit
wiring.
(d) Fuses. When fuses are installed or
removed with one or both terminals energized, special tools insulated for the
voltage shall be used.
(e) Cords and cables. (1) Worn or
frayed electric cords or cables shall not
be used.
(2) Extension cords shall not be fastened with staples, hung from nails, or
suspended by wire.
[44 FR 8577, Feb. 9, 1979; 44 FR 20940, Apr. 6,
1979, as amended at 55 FR 42328, Oct. 18, 1990;
58 FR 35179, June 30, 1993; 61 FR 9251, Mar. 7,
1996; 61 FR 41738, Aug. 12, 1996]
§ 1926.417
cuits.
Lockout and tagging of cir-
(a) Controls. Controls that are to be
deactivated during the course of work
on energized or deenergized equipment
or circuits shall be tagged.
(b) Equipment and circuits. Equipment
or circuits that are deenergized shall
be rendered inoperative and shall have
tags attached at all points where such
equipment or circuits can be energized.
(c) Tags. Tags shall be placed to identify plainly the equipment or circuits
being worked on.
[44 FR 8577, Feb. 9, 1979; 44 FR 20940, Apr. 6,
1979, as amended at 55 FR 42328, Oct. 18, 1990;
58 FR 35181, June 30, 1993; 61 FR 9251, Mar. 7,
1996; 61 FR 41739, Aug. 12, 1996]]
§§ 1926.418–1926.430
[Reserved]
SAFETY-RELATED MAINTENANCE AND
ENVIRONMENTAL CONSIDERATIONS
§ 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. There shall be no
loose or missing screws, gaskets,
threaded connections, seals, or other
impairments to a tight condition.
§ 1926.432 Environmental
deterioration of equipment.
(a) Deteriorating agents—(1) Unless
identified for use in the operating envi-
ronment, no conductors or equipment
shall be located:
(i) In damp or wet locations;
(ii) Where exposed to gases, fumes,
vapors, liquids, or other agents having
a deteriorating effect on the conductors or equipment; or
(iii) Where exposed to excessive temperatures.
(2) Control equipment, utilization
equipment, and busways approved for
use in dry locations only shall be protected against damage from the weather during building construction.
(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.
§§ 1926.433–1926.440
[Reserved]
SAFETY REQUIREMENTS FOR SPECIAL
EQUIPMENT
§ 1926.441
ing.
Batteries and battery charg-
(a) General requirements—(1) Batteries
of the unsealed type shall be located in
enclosures with outside vents or in well
ventilated rooms and shall be arranged
so as to prevent the escape of fumes,
gases, or electrolyte spray into other
areas.
(2) Ventilation shall be provided to
ensure diffusion of the gases from the
battery and to prevent the accumulation of an explosive mixture.
(3) Racks and trays shall be substantial and shall be treated to make them
resistant to the electrolyte.
(4) Floors shall be of acid resistant
construction unless protected from
acid accumulations.
(5) Face shields, aprons, and rubber
gloves shall be provided for workers
handling acids or batteries.
(6) Facilities for quick drenching of
the eyes and body shall be provided
within 25 feet (7.62 m) of battery handling areas.
(7) Facilities shall be provided for
flushing and neutralizing spilled electrolyte and for fire protection.
(b) Charging—(1) Battery charging installations shall be located in areas
designated for that purpose.
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Occupational Safety and Health Admin., Labor
(2) Charging apparatus shall be protected from damage by trucks.
(3) When batteries are being charged,
the vent caps shall be kept in place to
avoid electrolyte spray. Vent caps shall
be maintained in functioning condition.
§§ 1926.442–1926.448
[Reserved]
DEFINITIONS
§ 1926.449 Definitions applicable to
this subpart.
The definitions given in this section
apply to the terms used in subpart K.
The definitions given here for ‘‘approved’’ and ‘‘qualified person’’ apply,
instead of the definitions given in
§ 1926.32, to the use of these terms in
subpart K.
Acceptable. An installation or equipment is acceptable to the Assistant
Secretary of Labor, and approved within the meaning of this subpart K:
(a) If it is accepted, or certified, or
listed, or labeled, or otherwise determined to be safe by a qualified testing
laboratory capable of determining the
suitability of materials and equipment
for installation and use in accordance
with this standard; or
(b) With respect to an installation or
equipment of a kind which no qualified
testing laboratory accepts, certifies,
lists, labels, or determines to be safe, if
it is inspected or tested by another
Federal agency, or by a State, municipal, or other local authority responsible for enforcing occupational safety
provisions of the National Electrical
Code, and found in compliance with
those provisions; or
(c) With respect to custom-made
equipment or related installations
which are designed, fabricated for, and
intended for use by a particular customer, if it is determined to be safe for
its intended use by its manufacturer on
the basis of test data which the employer keeps and makes available for
inspection to the Assistant Secretary
and his authorized representatives.
Accepted. An installation is ‘‘accepted’’ if it has been inspected and found
to be safe by a qualified testing laboratory.
Accessible. (As applied to wiring
methods.) Capable of being removed or
exposed without damaging the building
§ 1926.449
structure or finish, or not permanently
closed in by the structure or finish of
the building. (See ‘‘concealed’’ and ‘‘exposed.’’)
Accessible. (As applied to equipment.)
Admitting close approach; not guarded
by locked doors, elevation, or other effective means. (See‘‘Readily accessible.’’)
Ampacity. The current in amperes a
conductor can carry continuously
under the conditions of use without exceeding its temperature rating.
Appliances. Utilization equipment,
generally other than industrial, normally built in standardized sizes or
types, which is installed or connecetcd
as a unit to perform one or more functions.
Approved. Acceptable to the authority enforcing this subpart. The authority enforcing this subpart is the Assistant Secretary of Labor for Occupational Safety and Health. The definition of ‘‘acceptable’’ indicates what is
acceptable to the Assistant Secretary
of Labor, and therefore approved within the meaning of this subpart.
Askarel. A generic term for a group of
nonflammable synthetic chlorinated
hydrocarbons used as electrical insulating media. Askarels of various
compositional types are used. Under
arcing conditions the gases produced,
while consisting predominantly of noncombustible hydrogen chloride, can include varying amounts of combustible
gases depending upon the askarel type.
Attachment plug (Plug cap)(Cap). A device which, by insertion in a receptacle, establishes connection between
the conductors of the attached flexible
cord and the conductors connected permanently to the receptacle.
Automatic. Self-acting, operating by
its own mechanism when actuated by
some impersonal influence, as for example, a change in current strength,
pressure, temperature, or mechanical
configuration.
Bare conductor. See ‘‘Conductor.’’
Bonding. The permanent joining of
metallic parts to form an electrically
conductive path which will assure electrical continuity and the capacity to
conduct safely any current likely to be
imposed.
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§ 1926.449
29 CFR Ch. XVII (7–1–14 Edition)
Bonding jumper. A reliable conductor
to assure the required electrical conductivity between metal parts required
to be electrically connected.
Branch circuit. The circuit conductors
between the final overcurrent device
protecting the circuit and the outlet(s).
Building. A structure which stands
alone or which is cut off from adjoining
structures by fire walls with all openings therein protected by approved fire
doors.
Cabinet. An enclosure designed either
for surface or flush mounting, and provided with a frame, mat, or trim in
which a swinging door or doors are or
may be hung.
Certified. Equipment is ‘‘certified’’ if
it:
(a) Has been tested and found by a
qualified testing laboratory to meet
applicable test standards or to be safe
for use in a specified manner, and
(b) Is of a kind whose production is
periodically inspected by a qualified
testing laboratory. Certified equipment
must bear a label, tag, or other record
of certification.
Circuit breaker—(a) (600 volts nominal, or less.) A device designed to open
and close a circuit by nonautomatic
means and to open the circuit automatically on a predetermined overcurrent without injury to itself when
properly applied within its rating.
(b) (Over 600 volts, nominal.) A
switching device capable of making,
carrying, and breaking currents under
normal circuit conditions, and also
making, carrying for a specified time,
and breaking currents under specified
abnormal circuit conditions, such as
those of short circuit.
Class I locations. Class I locations are
those in which flammable gases or vapors are or may be present in the air in
quantities sufficient to produce explosive or ignitible mixtures. Class I locations include the following:
(a) Class I, Division 1. A Class I, Division 1 location is a location:
(1) In which ignitible concentrations
of flammable gases or vapors may exist
under normal operating conditions; or
(2) In which ignitible concentrations
of such gases or vapors may exist frequently because of repair or maintenance operations or because of leakage;
or
(3) In which breakdown or faulty operation of equipment or processes
might release ignitible concentrations
of flammable gases or vapors, and
might also cause simultaneous failure
of electric equipment.
NOTE: This classification usually includes
locations where volatile flammable liquids
or liquefied flammable gases are transferred
from one container to another; interiors of
spray booths and areas in the vicinity of
spraying and painting operations where volatile flammable solvents are used; locations
containing open tanks or vats of volatile
flammable liquids; drying rooms or compartments for the evaporation of flammable solvents; inadequately ventilated pump rooms
for flammable gas or for volatile flammable
liquids; and all other locations where ignitible concentrations of flammable vapors or
gases are likely to occur in the course of normal operations.
(b) Class I, Division 2. A Class I, Division 2 location is a location:
(1) In which volatile flammable liquids or flammable gases are handled,
processed, or used, but in which the
hazardous liquids, vapors, or gases will
normally be confined within closed
containers or closed systems from
which they can escape only in case of
accidental rupture or breakdown of
such containers or systems, or in case
of abnormal operation of equipment; or
(2) In which ignitible concentrations
of gases or vapors are normally prevented by positive mechanical ventilation, and which might become hazardous through failure or abnormal operations of the ventilating equipment;
or
(3) That is adjacent to a Class I, Division 1 location, and to which ignitible
concentrations of gases or vapors
might occasionally be communicated
unless such communication is prevented by adequate positive-pressure
ventilation from a source of clean air,
and effective safeguards against ventilation failure are provided.
NOTE: This classification usually includes
locations where volatile flammable liquids
or flammable gases or vapors are used, but
which would become hazardous only in case
of an accident or of some unusual operating
condition. The quantity of flammable material that might escape in case of accident,
the adequacy of ventilating equipment, the
total area involved, and the record of the industry or business with respect to explosions
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Occupational Safety and Health Admin., Labor
or fires are all factors that merit consideration in determining the classification and
extent of each location.
Piping without valves, checks, meters, and
similar devices would not ordinarily introduce a hazardous condition even though used
for flammable liquids or gases. Locations
used for the storage of flammable liquids or
of liquefied or compressed gases in sealed
containers would not normally be considered
hazardous unless also subject to other hazardous conditions.
Electrical conduits and their associated
enclosures separated from process fluids by a
single seal or barrier are classed as a Division 2 location if the outside of the conduit
and enclosures is a nonhazardous location.
Class II locations. Class II locations
are those that are hazardous because of
the presence of combustible dust. Class
II locations include the following:
(a) Class II, Division 1. A Class II, Division 1 location is a location:
(1) In which combustible dust is or
may be in suspension in the air under
normal operating conditions, in quantities sufficient to produce explosive or
ignitible mixtures; or
(2) Where mechanical failure or abnormal operation of machinery or
equipment might cause such explosive
or ignitible mixtures to be produced,
and might also provide a source of ignition through simultaneous failure of
electric equipment, operation of protection devices, or from other causes,
or
(3) In which combustible dusts of an
electrically conductive nature may be
present.
NOTE: Combustible dusts which are electrically nonconductive include dusts produced in the handling and processing of grain
and grain products, pulverized sugar and
cocoa, dried egg and milk powders, pulverized spices, starch and pastes, potato and
woodflour, oil meal from beans and seed,
dried hay, and other organic materials which
may produce combustible dusts when processed or handled. Dusts containing magnesium or aluminum are particularly hazardous and the use of extreme caution is necessary to avoid ignition and explosion.
(b) Class II, Division 2. A Class II, Division 2 location is a location in which:
(1) Combustible dust will not normally be in suspension in the air in
quantities sufficient to produce explosive or ignitible mixtures, and dust accumulations are normally insufficient
to interfere with the normal operation
§ 1926.449
of electrical equipment or other apparatus; or
(2) Dust may be in suspension in the
air as a result of infrequent malfunctioning of handling or processing
equipment, and dust accumulations resulting therefrom may be ignitible by
abnormal operation or failure of electrical equipment or other apparatus.
NOTE: This classification includes locations where dangerous concentrations of suspended dust would not be likely but where
dust accumulations might form on or in the
vicinity of electric equipment. These areas
may contain equipment from which appreciable quantities of dust would escape under
abnormal operating conditions or be adjacent to a Class II Division 1 location, as described above, into which an explosive or ignitible concentration of dust may be put into
suspension under abnormal operating conditions.
Class III locations. Class III locations
are those that are hazardous because of
the presence of easily ignitible fibers
or flyings but in which such fibers or
flyings are not likely to be in suspension in the air in quantities sufficient
to produce ignitible mixtures. Class 111
locations include the following:
(a) Class III, Division 1. A Class III,
Division 1 location is a location in
which easily ignitible fibers or materials producing combustible flyings are
handled, manufactured, or used.
NOTE: Easily ignitible fibers and flyings include rayon, cotton (including cotton linters
and cotton waste), sisal or henequen, istle,
jute, hemp, tow, cocoa fiber, oakum, baled
waste kapok, Spanish moss, excelsior, sawdust, woodchips, and other material of similar nature.
(b) Class III, Division 2. A Class III,
Division 2 location is a location in
which easily ignitible fibers are stored
or handled, except in process of manufacture.
Collector ring. A collector ring is an
assembly of slip rings for transferring
electrical energy from a stationary to
a rotating member.
Concealed. Rendered inaccessible by
the structure or finish of the building.
Wires in concealed raceways are considered concealed, even though they
may become accessible by withdrawing
them. [See ‘‘Accessible. (As applied to
wiring methods.)’’]
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§ 1926.449
29 CFR Ch. XVII (7–1–14 Edition)
Conductor—(a) Bare. A conductor having no covering or electrical insulation
whatsoever.
(b) Covered. A conductor encased
within material of composition or
thickness that is not recognized as
electrical insulation.
(c) Insulated. A conductor encased
within material of composition and
thickness that is recognized as electrical insulation.
Controller. A device or group of devices that serves to govern, in some
predetermined manner, the electric
power delivered to the apparatus to
which it is connected.
Covered conductor. See ‘‘Conductor.’’
Cutout. (Over 600 volts, nominal.) An
assembly of a fuse support with either
a fuseholder, fuse carrier, or disconnecting blade. The fuseholder or
fuse carrier may include a conducting
element (fuse link), or may act as the
disconnecting blade by the inclusion of
a nonfusible member.
Cutout box. An enclosure designed for
surface mounting and having swinging
doors or covers secured directly to and
telescoping with the walls of the box
proper. (See ‘‘Cabinet.’’)
Damp location. See ‘‘Location.’’
Dead front. Without live parts exposed to a person on the operating side
of the equipment.
Device. A unit of an electrical system
which is intended to carry but not utilize electric energy.
Disconnecting means. A device, or
group of devices, or other means by
which the conductors of a circuit can
be disconnected from their source of
supply.
Disconnecting (or Isolating) switch.
(Over 600 volts, nominal.) A mechanical
switching device used for isolating a
circuit or equipment from a source of
power.
Dry location. See ‘‘Location.’’
Enclosed. Surrounded by a case, housing, fence or walls which will prevent
persons from accidentally contacting
energized parts.
Enclosure. The case or housing of apparatus, or the fence or walls surrounding an installation to prevent
personnel from accidentally contacting
energized parts, or to protect the
equipment from physical damage.
Equipment. A general term including
material, fittings, devices, appliances,
fixtures, apparatus, and the like, used
as a part of, or in connection with, an
electrical installation.
Equipment grounding conductor. See
‘‘Grounding conductor, equipment.’’
Explosion-proof apparatus. Apparatus
enclosed in a case that is capable of
withstanding an explosion of a specified gas or vapor which may occur
within it and of preventing the ignition
of a specified gas or vapor surrounding
the enclosure by sparks, flashes, or explosion of the gas or vapor within, and
which operates at such an external
temperature that it will not ignite a
surrounding flammable atmosphere.
Exposed. (As applied to live parts.)
Capable of being inadvertently touched
or approached nearer than a safe distance by a person. It is applied to parts
not suitably guarded, isolated, or insulated. (See ‘‘Accessible and ‘‘Concealed.’’)
Exposed. (As applied to wiring methods.) On or attached to the surface or
behind panels designed to allow access.
[See ‘‘Accessible. (As applied to wiring
methods.)’’]
Exposed.
(For
the
purposes
of
§ 1926.408(d), Communications systems.)
Where the circuit is in such a position
that in case of failure of supports or insulation, contact with another circuit
may result.
Externally operable. Capable of being
operated without exposing the operator
to contact with live parts.
Feeder. All circuit conductors between the service equipment, or the
generator switchboard of an isolated
plant, and the final branch-circuit
overcurrent device.
Festoon lighting. A string of outdoor
lights suspended between two points
more than 15 feet (4.57 m) apart.
Fitting. An accessory such as a locknut, bushing, or other part of a wiring
system that is intended primarily to
perform a mechanical rather than an
electrical function.
Fuse. (Over 600 volts, nominal.) An
overcurrent protective device with a
circuit opening fusible part that is
heated and severed by the passage of
overcurrent through it. A fuse comprises all the parts that form a unit capable of performing the prescribed
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Occupational Safety and Health Admin., Labor
functions. It may or may not be the
complete device necessary to connect
it into an electrical circuit.
Ground. A conducting connection,
whether intentional or accidental, between an electrical circuit or equipment and the earth, or to some conducting body that serves in place of the
earth.
Grounded. Connected to earth or to
some conducting body that serves in
place of the earth.
Grounded, effectively (Over 600 volts,
nominal.) Permanently connected to
earth through a ground connection of
sufficiently low impedance and having
sufficient ampacity that ground fault
current which may occur cannot build
up to voltages dangerous to personnel.
Grounded conductor. A system or circuit conductor that is intentionally
grounded.
Grounding conductor. A conductor
used to connect equipment or the
grounded circuit of a wiring system to
a grounding electrode or electrodes.
Grounding conductor, equipment. The
conductor used to connect the noncurrent-carrying metal parts of equipment, raceways, and other enclosures
to the system grounded conductor and/
or the grounding electrode conductor
at the service equipment or at the
source of a separately derived system.
Grounding electrode conductor. The
conductor used to connect the grounding electrode to the equipment grounding conductor and/or to the grounded
conductor of the circuit at the service
equipment or at the source of a separately derived system.
Ground-fault circuit interrupter. A device for the protection of personnel
that functions to deenergize a circuit
or portion thereof within an established period of time when a current to
ground exceeds some predetermined
value that is less than that required to
operate the overcurrent protective device of the supply circuit.
Guarded. Covered, shielded, fenced,
enclosed, or otherwise protected by
means of suitable covers, casings, barriers, rails, screens, mats, or platforms
to remove the likelihood of approach
to a point of danger or contact by persons or objects.
Hoistway. Any shaftway, hatchway,
well hole, or other vertical opening or
§ 1926.449
space in which an elevator or dumbwaiter is designed to operate.
Identified (conductors or terminals).
Identified, as used in reference to a
conductor or its terminal, means that
such conductor or terminal can be recognized as grounded.
Identified (for the use). Recognized as
suitable for the specific purpose, function, use, environment, application,
etc. where described as a requirement
in this standard. Suitability of equipment for a specific purpose, environment, or application is determined by a
qualified testing laboratory where such
identification includes labeling or listing.
Insulated conductor. See ‘‘Conductor.’’
Interrupter switch. (Over 600 volts,
nominal.) A switch capable of making,
carrying, and interrupting specified
currents.
Intrinsically safe equipment and associated wiring. Equipment and associated
wiring in which any spark or thermal
effect, produced either normally or in
specified fault conditions, is incapable,
under certain prescribed test conditions, of causing ignition of a mixture
of flammable or combustible material
in air in its most easily ignitible concentration.
Isolated. Not readily accessible to
persons unless special means for access
are used.
Isolated power system. A system comprising an isolating transformer or its
equivalent, a line isolation monitor,
and its ungrounded circuit conductors.
Labeled. Equipment or materials to
which has been attached a label, symbol or other identifying mark of a
qualified testing laboratory which indicates compliance with appropriate
standards or performance in a specified
manner.
Lighting outlet. An outlet intended for
the direct connection of a lampholder,
a lighting fixture, or a pendant cord
terminating in a lampholder.
Listed. Equipment or materials included in a list published by a qualified
testing laboratory whose listing states
either that the equipment or material
meets appropriate standards or has
been tested and found suitable for use
in a specified manner.
Location—(a) Damp location. Partially
protected locations under canopies,
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§ 1926.449
29 CFR Ch. XVII (7–1–14 Edition)
marquees, roofed open porches, and
like locations, and interior locations
subject to moderate degrees of moisture, such as some basements.
(b) Dry location. A location not normally subject to dampness or wetness.
A location classified as dry may be
temporarily subject to dampness or
wetness, as in the case of a building
under construction.
(c) Wet location. Installations underground or in concrete slabs or masonry
in direct contact with the earth, and
locations subject to saturation with
water or other liquids, such as locations exposed to weather and unprotected.
Mobile
X-ray.
X-ray
equipment
mounted on a permanent base with
wheels and/or casters for moving while
completely assembled.
Motor control center. An assembly of
one or more enclosed sections having a
common power bus and principally containing motor control units.
Outlet. A point on the wiring system
at which current is taken to supply
utilization equipment.
Overcurrent. Any current in excess of
the rated current of equipment or the
ampacity of a conductor. It may result
from overload (see definition), short
circuit, or ground fault. A current in
excess of rating may be accommodated
by certain equipment and conductors
for a given set of conditions. Hence the
rules for overcurrent protection are
specific for particular situations.
Overload. Operation of equipment in
excess of normal, full load rating, or of
a conductor in excess of rated
ampacity which, when it persists for a
sufficient length of time, would cause
damage or dangerous overheating. A
fault, such as a short circuit or ground
fault,
is
not
an
overload.
(See‘‘Overcurrent.’’)
Panelboard. A single panel or group of
panel units designed for assembly in
the form of a single panel; including
buses, automatic overcurrent devices,
and with or without switches for the
control of light, heat, or power circuits; designed to be placed in a cabinet or cutout box placed in or against
a wall or partition and accessible only
from the front. (See ‘‘Switchboard.’’)
Portable X-ray. X-ray equipment designed to be hand-carried.
Power fuse. (Over 600 volts, nominal.)
See ‘‘Fuse.’’
Power outlet. An enclosed assembly
which may include receptacles, circuit
breakers, fuseholders, fused switches,
buses and watt-hour meter mounting
means; intended to serve as a means
for distributing power required to operate mobile or temporarily installed
equipment.
Premises wiring system. That interior
and exterior wiring, including power,
lighting, control, and signal circuit
wiring together with all of its associated hardware, fittings, and wiring devices, both permanently and temporarily installed, which extends from
the load end of the service drop, or load
end of the service lateral conductors to
the outlet(s). Such wiring does not include wiring internal to appliances, fixtures, motors, controllers, motor control centers, and similar equipment.
Qualified person. One familiar with
the construction and operation of the
equipment and the hazards involved.
Qualified testing laboratory. A properly equipped and staffed testing laboratory which has capabilities for and
which provides the following services:
(a) Experimental testing for safety of
specified items of equipment and materials referred to in this standard to determine compliance with appropriate
test standards or performance in a
specified manner;
(b) Inspecting the run of such items
of equipment and materials at factories for product evaluation to assure
compliance with the test standards;
(c)
Service-value
determinations
through field inspections to monitor
the proper use of labels on products
and with authority for recall of the
label in the event a hazardous product
is installed;
(d) Employing a controlled procedure
for identifying the listed and/or labeled
equipment or materials tested; and
(e) Rendering creditable reports or
findings that are objective and without
bias of the tests and test methods employed.
Raceway. A channel designed expressly for holding wires, cables, or
busbars, with additional functions as
permitted in this subpart. Raceways
may be of metal or insulating material,
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Occupational Safety and Health Admin., Labor
and the term includes rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquidtight
flexible metal conduit, flexible metallic tubing, flexible metal conduit, electrical metallic tubing, underfloor raceways, cellular concrete floor raceways,
cellular metal floor raceways, surface
raceways, wireways, and busways.
Readily accessible. Capable of being
reached quickly for operation, renewal,
or inspections, without requiring those
to whom ready access is requisite to
climb over or remove obstacles or to
resort to portable ladders, chairs, etc.
(See ‘‘Accessible.’’)
Receptacle. A receptacle is a contact
device installed at the outlet for the
connection of a single attachment
plug. A single receptacle is a single
contact device with no other contact
device on the same yoke. A multiple
receptacle is a single device containing
two or more receptacles.
Receptacle outlet. An outlet where one
or more receptacles are installed.
Remote-control circuit. Any electric
circuit that controls any other circuit
through a relay or an equivalent device.
Sealable equipment. Equipment enclosed in a case or cabinet that is provided with a means of sealing or locking so that live parts cannot be made
accessible without opening the enclosure. The equipment may or may not
be operable without opening the enclosure.
Separately derived system. A premises
wiring system whose power is derived
from generator, transformer, or converter windings and has no direct electrical connection, including a solidly
connected grounded circuit conductor,
to supply conductors originating in another system.
Service. The conductors and equipment for delivering energy from the
electricity supply system to the wiring
system of the premises served.
Service conductors. The supply conductors that extend from the street
main or from transformers to the service equipment of the premises supplied.
Service drop. The overhead service
conductors from the last pole or other
aerial support to and including the
splices, if any, connecting to the serv-
§ 1926.449
ice-entrance conductors at the building
or other structure.
Service-entrance conductors, overhead
system. The service conductors between
the terminals of the service equipment
and a point usually outside the building, clear of building walls, where
joined by tap or splice to the service
drop.
Service-entrance conductors, underground system. The service conductors
between the terminals of the service
equipment and the point of connection
to the service lateral. Where service
equipment is located outside the building walls, there may be no service-entrance conductors, or they may be entirely outside the building.
Service equipment. The necessary
equipment, usually consisting of a circuit breaker or switch and fuses, and
their accessories, located near the
point of entrance of supply conductors
to a building or other structure, or an
otherwise defined area, and intended to
constitute the main control and means
of cutoff of the supply.
Service raceway. The raceway that encloses the service-entrance conductors.
Signaling circuit. Any electric circuit
that energizes signaling equipment.
Switchboard. A large single panel,
frame, or assembly of panels which
have switches, buses, instruments,
overcurrent and other protective devices mounted on the face or back or
both. Switchboards are generally accessible from the rear as well as from
the front and are not intended to be installed in cabinets. (See ‘‘Panelboard.’’)
Switches—(a) General-use switch. A
switch intended for use in general distribution and branch circuits. It is
rated in amperes, and it is capable of
interrupting its rated current at its
rated voltage.
(b) General-use snap switch. A form of
general-use switch so constructed that
it can be installed in flush device boxes
or on outlet box covers, or otherwise
used in conjunction with wiring systems recognized by this subpart.
(c) Isolating switch. A switch intended
for isolating an electric circuit from
the source of power. It has no interrupting rating, and it is intended to be
operated only after the circuit has been
opened by some other means.
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§ 1926.450
29 CFR Ch. XVII (7–1–14 Edition)
(d) Motor-circuit switch. A switch,
rated in horsepower, capable of interrupting the maximum operating overload current of a motor of the same
horsepower rating as the switch at the
rated voltage.
Switching devices. (Over 600 volts,
nominal.) Devices designed to close
and/or open one or more electric circuits. Included in this category are circuit breakers, cutouts, disconnecting
(or isolating) switches, disconnecting
means, and interrupter switches.
Transportable X-ray. X-ray equipment
installed in a vehicle or that may readily be disassembled for transport in a
vehicle.
Utilization
equipment.
Utilization
equipment means equipment which utilizes electric energy for mechanical,
chemical, heating, lighting, or similar
useful purpose.
Utilization system. A utilization system is a system which provides electric
power and light for employee workplaces, and includes the premises wiring system and utilization equipment.
Ventilated. Provided with a means to
permit circulation of air sufficient to
remove an excess of heat, fumes, or vapors.
Volatile flammable liquid. A flammable
liquid having a flash point below 38 degrees C (100 degrees F) or whose temperature is above its flash point, or a
Class II combustible liquid having a
vapor pressure not exceeding 40 psia
(276 kPa) at 38 °C (100 °F) whose temperature is above its flash point.
Voltage. (Of a circuit.) The greatest
root-mean-square (effective) difference
of potential between any two conductors of the circuit concerned.
Voltage, nominal. A nominal value assigned to a circuit or system for the
purpose of conveniently designating its
voltage class (as 120/240, 480Y/277, 600,
etc.). The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment.
Voltage to ground. For grounded circuits, the voltage between the given
conductor and that point or conductor
of the circuit that is grounded; for
ungrounded circuits, the greatest voltage between the given conductor and
any other conductor of the circuit.
Watertight. So constructed that moisture will not enter the enclosure.
Weatherproof. So constructed or protected that exposure to the weather
will not interfere with successful operation. Rainproof, raintight, or watertight equipment can fulfill the requirements for weatherproof where varying
weather conditions other than wetness,
such as snow, ice, dust, or temperature
extremes, are not a factor.
Wet location. See ‘‘Location.’’
Subpart L—Scaffolds
AUTHORITY: 40 U.S.C. 333; 29 U.S.C. 653, 655,
657; Secretary of Labor’s Order Nos. 1–90 (55
FR 9033), 5–2007 (72 FR 31159), or 1–2012 (77 FR
3912); and 29 CFR part 1911.
SOURCE: 61 FR 46104, Aug. 30, 1996, unless
otherwise noted.
§ 1926.450 Scope, application and definitions applicable to this subpart.
(a) Scope and application. This subpart applies to all scaffolds used in
workplaces covered by this part. It
does not apply to crane or derrick suspended personnel platforms. The criteria for aerial lifts are set out exclusively in § 1926.453.
(b) Definitions. Adjustable suspension
scaffold means a suspension scaffold
equipped with a hoist(s) that can be operated by an employee(s) on the scaffold.
Bearer (putlog) means a horizontal
transverse scaffold member (which
may be supported by ledgers or runners) upon which the scaffold platform
rests and which joins scaffold uprights,
posts, poles, and similar members.
Boatswains’ chair means a singlepoint adjustable suspension scaffold
consisting of a seat or sling designed to
support one employee in a sitting position.
Body belt (safety belt) means a strap
with means both for securing it about
the waist and for attaching it to a lanyard, lifeline, or deceleration device.
Body harness means a design of straps
which may be secured about the employee in a manner to distribute the
fall arrest forces over at least the
thighs, pelvis, waist, chest and shoulders, with means for attaching it to
other components of a personal fall arrest system.
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| File Type | application/pdf |
| File Modified | 2014-08-07 |
| File Created | 2014-08-07 |