[Code of Federal Regulations]
[Title 29, Volume 8]
[Revised as of July 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 29CFR1926.449]
[Page 265-273]
TITLE 29--LABOR
CHAPTER XVII--OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT
OF LABOR
PART 1926_SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION--Table of Contents
Subpart K_Electrical
Sec. 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 Sec. 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 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
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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.
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.
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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 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 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
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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.)'']
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.''
[[Page 269]]
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 Sec. 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 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 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.
[[Page 270]]
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, 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
[[Page 271]]
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, 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 service-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
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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.
(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 [deg]C (100 [deg]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,
[[Page 273]]
such as snow, ice, dust, or temperature extremes, are not a factor.
Wet location. See ``Location.''
