100 NEC Definitions
Inverse Time Circuit Breaker
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Listed
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Multiwire Branch Circuit
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Appliance Branch Circuit
A branch circuit that supplies energy to one or more outlets to which appliances are to be connected and that has no permanently connected luminaires that are not a part of an appliance.
Individual Branch Circuit
A branch circuit that supplies only one utilization equipment.
General-Purpose Branch Circuit
A branch circuit that supplies two or more receptacles or outlets for lighting and appliances.
Luminaire
A complete lighting unit consisting of a light source ,lamp or lamps, together with the parts designed to position the light source and connected to the power supply. It may also include parts to protect the light source or the ballast or to distribute the light. A lampholder itself is not a luminaire.
Grounding Electrode
A conducting object through which a direct connection to earth is established.
Insulated Conductor
A conductor encased with material of composition and thickness that is recognized by this code as insulation.
Covered Conductor
A conductor encased within a material of composition or thickness that is not recognized by this code as electrical insulation
Grounding Electrode Conductor
A conductor used to connect the system, ground conductor, or the equipment to a grounding electrode, or to a point on the grounding electrode system.
Receptacle
A contact device installed at the outlet for the connection of an attachment plug, or for the direct connection of electrical utilization equipment. Designed to mate with the corresponding contact device. A single receptacle is a single contact device with no other contact device on the same yoke.
Circuit Breaker
A device designed to open and close a circuit by nonautomatic means and to open the circuit automatically on a predetermined overcurrent without damage to itself when properly applied within its rating
Ground-Fault Circuit Interrupter
A device intended for the protection of personnel that functions to de energize a circuit or portion thereof within an established period of time when a current to ground exceeds the values established for a class A device.
Arc-Fault Circuit Interrupter
A device intended to provide protection from the effects of arc fault by recognizing characteristics unique to arcing and by functuion to deenergize the circuit when an arc-fault is dectected
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
Intersystem Bonding Termination
A device that provides a means for connecting intersystem bonding, conductors for communication system to the grounding electrode system
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
General-Use Snap Switch
A form of general use switch constructed so that it can be installed in device boxes or on box covers or otherwise used in conjunction with wiring systems recognized by this code.
Switchboard
A large single panel, frame or assembly of panels on which are mounted on the face, back, or both, switches, overcurrent and other protective devices, busses, and usually instruments. these assemblies are normally accessible from the rear as well as from the front and are not intended to be installed in cabinets.
Continuous Load
A load where the maximum current is expected to continue for three hours or more.
Nonlinear Load
A load where the wave shape of the steady state current does not follow the wave shape of the applied voltage.
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.
Nominal Voltage
A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class.
OUtlet
A point on the wiring system at which current is taken to supply utilization equipment.
Dwelling Unit
A single unit, providing complete and independent living facilities, for one or more persons, including permanent provisions for living, sleeping, cooking, and sanitation
Building
A structure that stands alone or that is separated from adjoining structures by firewalls
General-Use Switch
A switch intended for use and general distribution and branch circuits. It is rated amperes and it is capable of interrupting its rated current at its rated voltage.
Motor-Circuit switch
A switch rated in horsepower that is capable interrupting the maximum operating overload current of a motor of the same horse power rating as the switch at the rated voltage.
Grounded Conductor
A system or circuit conductor that is intentionally grounded.
Multioutlet assembly
A type of surface, flush, or free standing raceway designed to hold conductors and receptacles, assembled in the field or at the factory.
Device
A unit of an electrical system, other than a conductor, that carries or controls electric energy as its principle function
Approved
Acceptable to the authority having jurisdiction
Feeder
All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch circuit overcurrent device.
Fitting
An accessory such a locknut bushing or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function.
Switchgear
An assembly completely enclosed on all sides and top with sheet metal (except ventilation opening and inspection windows) and containing primary power circuit switching, interrupting devices, or both, with busses and connections. The assembly may include control and auxiliary devices. Access to the interior of the enclosure is provided by doors, removable covers, or both.
Motor Control Center
An assembly of one or more sections having a common power bus in principally containing motor control units.
Transfer Switch
An automatic or nonautomatic device for transferring one or more load conductor from one power source to another.
Separately Derived System
An electrical source, other than a service, having no direct connections to circuit conductors of any other electrical source, other than those established by grounding and bonding connections.
Ground-Fault Current Path
An electrically conductive path from the point of a ground fault on a wiring system through normally non current carrying conductors, equipment, or the earth to the electrical supply source
Cutout Box
An enclosure designed for surface mounting that has swinging doors or covers secured directly to and telescoping with the walls of the enclosure
Cabinet
An enclosure that is designed for either surface mounting or flush mounting and is provided with a frame, mat or trim in which a swinging door or doors are or can be hung
Effective Ground-Fault Current Path
An intentionally constructed, low-impedance electrically conductive path designed and intended to carry current under ground fault conditions from the point of a ground fault on a wiring system to the electrical supply source and that facilitates the operation of the overcurrent protective device or ground-fault detectors
Authority Having Jurisdiction
An organization, office or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, an installation or a procedure
Lighting OUtlet
An outlet intended for the direct connection of a lamp holder or luminaire
Receptacle Outlet
An outlet where one or more receptacles are installed.
Ground Fault
An unintentional, electrically conductive connection between an ungrounded conductor of an electrical circuit in the normally non current carrying conductors metallic enclosures, metallic raceways, metallic equipment, or earth.
Power OUtlet
And enclosed assembly that may include receptacles, circuit breakers, fuse holders, fused switched, busses and watt/hour meter mounting means; intended to supply and control power to mobile homes, rec vehicles, park trailers, or boats, or to serve as a means for distributing power required to operate mobile or temporarily installed equipment.
Overcurrent
Any current in excess of the rating current of equipment or the ampacity of a conductor. It may result from overload, short circuit or ground fault.
In Sight From
Be visible and no more than 50 feet distant from the other.
Readily Accessibble
Capable of being reached quickly for operation, renewal, or inspection without requiring those to whom ready access is requisite to take action such as to use tools, to climb over or remove obstacles or to resort to portable ladders and so forth.
Bonded/Bonding
Connected to establish electrical continuity and conductivity
Grounded/Grounding
Connecting/to ground, or to a conductive body that extends the ground connection.
Raintight
Constructed or protected so that exposure to a beating rain will not result in the entrance of water under specified test conditions.
Weatherproof
Constructed or protected so that exposure to the weather will not interfere with successful operation
Watertight
Constructed so that moisture will not enter the enclosure under specified test conditions.
Rainproof
Constructed, protected or treated so as to prevent rain from interfering with the successful operation of the apparatus under specified test conditions.
Guarded
Covered ,shielded, fenced, enclosed, or otherwise protected by means of suitable covers, casing, barriers, rails, screens, mats or platforms, to remove the likelihood of approach or contact by persons or objects to a point of danger
Energized
Electrically connected to, or is, a source of voltage
Dusttight
Enclosures constructed so that the dust will not enter under specified test conditions
Explosion Proof Equipment
Equipment enclosed in a case that is capable of withstanding an explosion of a specified gas or vapor that may occur within it and of preventing the ignition of a specified gas or vapor surrounding the vapor by sparks, flashes, or explosion of the gas or vapor within and that operates at such an external temperature that a surrounding flammable atmosphere will not be ignited thereby.
Utilization Equipment
Equipment that utilizes electric energy for electronic, electromechanical, heating chemical, heating, lighting, or similar purposes.
Voltage to ground
For grounded circuits, the voltage between the given conductor and that point or conductor of the circuit that is grounded; for underground circuits, the greatest voltage between the given conductor and any other conductor of the circuit.
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 vehicle washing areas; and in unprotected locations exposed to weather
Premises Wiring (system)
Interior and exterior wiring, including power, lighting, control, and signal circuit wiring together, with all their associated hardware, fittings, and wiring devices, both permanently and temporarily installed. This includes (a) wiring from the service point or power source to the outlets or (b) wiring from and including the power source to the outlets where there is no service point.
Damp Location
Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of moisture.
Instantaneous Circuit Breaker
NO delay is purposly introduced in the tripping action of the circuit breaker.
Isolated (location)
Not readily accessible to persons unless special means for access are used
Exposed (as wiring methods)
On or attached to the surface or behind panels designed to allow access.
Qualified Person
One who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training to recognize and avoid the hazards involved.
Continuous Duty
Operating at a substantially constant load for an indefinitely long time
Intermittent Duty
Operation for alternate intervals of 1. load and no load 2. load and rest or 3.load, no load, and rest
Overload
Operation of equipment in excess of normal, full load rating, or of a conductor in excess of rating ampacity that, when it persists for a sufficient length of time, would cause damage or dangerous overheating. A fault, such as short circuit or ground fault, is not an overload.
Identified (as applied to equipment)
Recognizable as suitable for the specific purpose, function, use, environment, application, and so forth, where described in particular code requirement
Concealed
Rendered inaccessible by the structure or finish of the building
Enclosed
Surrounded by a case, housing, fence or walls, that prevents 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
Branch Circuit
The circuit conductors between the final overcurrent device protecting the circuit and the outlets
Equipment Grounding Conductor
The conductive paths that provide a ground fault current path and connects normally non current carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both.
Service
The conductors and equipment for delivering electric energy from the serving utility to the wiring system of the premises served.
Service Conductors
The conductors from the service point to the service disconnecting means.
System Bonding Jumper
The connection between the grounded circuit conduction and the supply side bonding jumper or the equipment grounding conductor or both of a seperately derived sytem
Equipment Bonding Jumper
The connection between two or more portions of the equipment grounding conductor
Interupting Rating
The highest current at rated voltage that a device is identified to interrupt under standard test conditions
Ampacity
The maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating
Service Equipment
The neccessary equipment, usually consisting of circuit breakers or switches and fuses and their accessories, connected to the load end of service conductors to a building or other structure, or an otherwise designated area, and intended to constitute the main control and cutoff of a supply.
Overhead Service Conductors
The overhead conductors between the service point and the first point of connection to the service entrance conductors at the building or other structure.
Service Drop
The overhead conductors between the utility electric supply system, and the service point.
Service Point
The point of connection between the facilities of the serving utility and the premises wiring.
Short-Circuit Current Rating
The prospective symmetrical fault current at a nominal voltage to which an apparatus or system is able to be connected without sustaining damage exceeding defined acceptance criteria.
Overhead System Service-Entrance Conductors
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 spliced to the service drop or overhead service conductors.
Underground System Service Entrance Conductors
The service conductors between the terminals of the service equipment and the point of connection to the service lateral or underground service conductors.
Underground Service Conductors
The underground conductors between the service point and the first point of connection to the service entrance conductors in a terminal box, meter, or other enclosure, inside or outside the building wall.
Service Lateral
The underground conductors between the utility electric supply system and the service point.
Appliance
Utilization equipment, generally other than industrial, that is normally built in standard sizes or types and is installed or connected as a unit to perform one or more functions such as clothes washing, air-conditions, food mixing, deep frying, and so forth.
Dead Front
Without live parts exposed to a person on the operating side of equipment
Panelboard
a single panel or group of panel units designed for assembly in the form of a single panel, including busses and automatic overcurrent devices, and equipped with or without switches for the control light, heat or power circuits; designed to be placed in a cabinet or cutout box, placed in or against the wall, wall, partition or other support; and accessible only from the front.
Ground-Fault Protection of Equipment
a system intended to provide protection of equipment from damaging line to ground fault currents by operating to cause a disconnecting means to open all ungrounded conductors of the faulted circuit. This protection is provided at current levels less than those required to protect conductors from damage through the operation of a supply circuit overcurrent device.
Live Parts
energized conductive components
Main Bonding Jumper
the connection between the grounded circuit conductor and the equipment grounding conductor at the service