NEC 17, Elect code definitions

Branch Circuit, Multiwire

A branch circuit that consists of two or more ungrounded conductors that have a voltage between them and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.

Branch Circuit, Appliance

A branch circuit that supplies energy to one or more outlets to which appliances are to be connected and that has no permanently connected luminaries that are not a part of an appliance.

Branch circuit, General Purpose

A branch circuit that supplies two or more receptacles or outlets for lighting and appliances.

Garage

A building or portion of a building in which one or more self-propelled vehicles can be kept for use, sale, storage, rental, repair, exhibition, or demonstration purposes.

Dwelling, One-Family

A building that consists solely of one dwelling unit.

Dwelling, Two-Family

A building that consists solely of two dwelling units.

Dwelling, Multifamily

A building that contains three or more dwelling units.

Composite Optical Fiber Cable.

A cable containing optical fibers and current-carrying electrical conductors.

Adjustable Speed Drive System

A combination of an adjustable speed drive, its associated motor(s), and auxiliary equipment.

Grounding Electrode

A conducting object through which a direct connection to earth is established.

Conductor, Insulated

A conductor encased within material of composition and thickness that is recognized by this Code as electrical insulation.

Conductor, Covered

A conductor encased within material of composition or thickness that is not recognized by this Code as electrical insulation.

Conductor, Bare

A conductor having no covering or electrical insulation whatsoever.

Cooking Unit, Counter-Mounted

A cooking appliance designed for mounting in or on a counter and consisting of one or more heating elements, internal wiring, and built-in or mountable controls.

Coaxial Cable.

A cylindrical assembly composed of a conductor centered inside a metallic tube or shield, separated by a dielectric material, and usually covered by an insulating jacket.

Circuit Breaker

A device designed to open and close a circuit by non-automatic means and to open the circuit automatically on a predetermined over-current without damage to itself when properly applied within its rating.

Ground-Fault Circuit Interrupter (GFCI)

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 (AFCI)

A device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc fault is detected.

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.

Connector, Pressure (Solderless)

A device that establishes a connection between two or more conductors or between one or more conductors and a terminal by means of mechanical pressure and without the use of solder.

Attachment Plug

A device that, by insertion in a receptacle, establishes a connection between the conductors of the attached flexible cord and the conductors connected permanently to the receptacle.

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.

Control Drawing [as applied to Hazardous (Classified) Locations].

A drawing or other document provided by the manufacturer of the intrinsically safe or associated apparatus, or of the nonincendive field wiring apparatus or associated nonincendive field wiring apparatus, that details the allowed interconnections between the intrinsically safe and associated apparatus or between the nonincendive field wiring apparatus or associated nonincendive field wiring apparatus.

Conductive Optical Fiber Cable.

A factory assembly of one or more optical fibers having an overall covering and containing non-current-carrying conductive member(s) such as metallic strength member(s), metallic vapor barrier(s), metallic armor or metallic sheath.

Cord Connector [as applied to Hazardous (Classified) Locations].

A fitting intended to terminate a cord to a box or similar device and reduce the strain at points of termination and may include an explosionproof, a dust-ignitionproof, or a flameproof seal.

Electric Sign

A fixed, stationary, or portable self-contained, electrically operated and/or electrically illuminated utilization equipment with words or symbols designed to convey information or attract attention.

Equipment

A general term including fitting devices appliances,luminaries, apparatus, machinery, and the like used as part of or in connection with an electrical installation.

Askarel

A generic term for a group of nonflammable synthetic chlorinated hydrocarbons used as electrical insulating media.

Continuous Load

A load where the maximum current is expected to continue for 3 hours or more.

Clothes Closet

A non-habitable room or space intended primarily for storage of garments and apparel.

Combustible Gas Detection System [as applied to Hazardous (Classified) Locations].

A protection technique utilizing stationary gas detectors in industrial establishments.

Bonding Conductor or Jumper

A reliable conductor to ensure the required electrical conductivity between metal parts required to be electrically connected.

Conduit Body

A separate portion of a conduit or tubing system that provides access through a removable cover(s) to the interior of the system at a junction of two or more sections of the system or at a terminal point of the system.

Cable Routing Assembly

A single channel or connected multiple channels, as well as associated fittings, forming a structural system that is used to support and route communications wires and cables, optical fiber cables, data cables associated with information technology and communications equipment, Class 2, Class 3, and Type PLTC cables, and power-limited fire alarm cables in plenum, riser, and general-purpose applications.

Dwelling unit

A single unit, providing complete and independent living facilities for one or more person, including permanent provisions for living, sleeping cooking, and sanitation.

Festoon Lighting

A string of outdoor lights that is suspended between two points.

Building

A structure that stands alone or that is separated from adjoining structures by fire walls.

Electrical Circuit Protective System

A system consisting of components and materials intended for installation as protection for specific electrical wiring systems with respect to the disruption of electrical circuit integrity upon exterior fire exposure.

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 over-current device.

Grounded Conductor

A system or circuit conductor that is intentionally grounded.

Device

A unit of an electrical system, other than a conductor, that carries or controls electric energy as its principal function.

Approved

Acceptable to the authority having jurisdiction.

Accessible as applied to equipment

Admitting close approach not guarded by locked doors, elevation or other effective means.

Feeder

All circuits conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit over current device.

Fitting

An accessory such as a lock-nut, bushing, or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function.

Bathroom

An area including a basin with one or more of the following: a toilet, a urinal, a tub, a shower, a bidet, or similar plumbing fixtures.

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.

Communications Raceway.

An enclosed channel of nonmetallic materials designed expressly for holding communications wires and cables; optical fiber cables; data cables associated with information technology and communications equipment; Class 2, Class 3, and Type PLTC cables; and power-limited fire alarm cables in plenum, riser, and general-purpose applications.

Cutout Box

An enclosure designed for surface mounting that has swinging doors or covers secured directly to and telescoping with the walls of the box proper.

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 over-current protective device or ground-fault detectors.

Field Evaluation Body (FEB).

An organization or part of an organization that performs field evaluations of electrical or other equipment.

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.

Electronically Actuated Fuse

An over-current protective device that generally consists of a control module that provides current-sensing, electronically derived time-current characteristics, energy to initiate tripping, and an interrupting module that interrupts current when an over-current occurs. Such fuses may or may not operate in a current-limiting fashion, depending on the type of control selected.

Ground Fault

An unintentional, electrically conductive connection between an ungrounded conductor of an electrical circuit and the normally non-current-carrying conductors, metallic enclosures, metallic raceways, metallic equipment, or earth.

Associated Apparatus [as applied to Hazardous (Classified) Locations].

Apparatus in which the circuits are not necessarily intrinsically safe themselves but that affects the energy in the intrinsically safe circuits and is relied on to maintain intrinsic safety.

Associated Nonincendive Field Wiring Apparatus [as applied to Hazardous(Classified) Locations].

Apparatus in which the circuits are not necessarily nonincendive themselves but that affect the energy in nonincendive field wiring circuits and are relied upon to maintain nonincendive energy levels.

Branch Circuit, Individual

Branch circuit that supplies only utilization equipment.

Exposed as applied to live parts

Capable of being inadvertently touched or approached nearer than a safe distance by a person.

Externally Operable

Capable of being operated without exposing the operator to contact with live parts.

Accessible, Readily (Readily Accessible)

Capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to actions such as to use tools, to climb over or remove obstacles, or to resort to portable ladders, and so forth.

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.

Copper Clad Aluminum Conductor

Conductor drawn from a copper clad aluminum rod, with copper metallurgic-ally bonded to an aluminum core where the copper forms a minimum of 10 percent of the cross sectional area of a solid conductor or each strand of a stranded conductor.

Grounded (Grounding)

Connected (connecting) to ground or to a conductive body that extends the ground connection.

Bonded (Bonding)

Connected to establish electrical continuity and conductivity.

Grounded, Solidly

Connected to ground without inserting any resistor or impedance device.

Dusttight

Constructed so that dust will not enter the enclosing case under specified test conditions.

Combustible Dust [as applied to Hazardous (Classified) Locations].

Dust particles that are 500 microns or smaller (i.e., material passing a U.S. No. 35 Standard Sieve as defined in ASTM E11-2015, Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves), and present a fire or explosion hazard when dispersed and ignited in air.

Energized

Electrically connected to , or is , a source of voltage.

Explosionproof 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 enclosure 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.

Dust-Ignitionproof [as applied to Hazardous (Classified) Locations].

Equipment enclosed in a manner that excludes dusts and does not permit arcs, sparks, or heat otherwise generated or liberated inside of the enclosure to cause ignition of exterior accumulations or atmospheric suspensions of a specified dust on or in the vicinity of the enclosure.

Field Labeled (as applied to evaluated products).

Equipment or materials to which has been attached a label, symbol, or other identifying mark of an FEB indicating the equipment or materials were evaluated and found to comply with requirements as described in an accompanying field evaluation report.

Charge Controller

Equipment that controls dc voltage or dc current, or both, and that is used to charge a battery or other energy storage device.

Battery system

Interconnected battery subsystems consisting of one or more storage batteries and battery chargers, and can include inverters, converters, and associated electrical equipment.

Duty, Periodic.

Intermittent operation in which the load conditions are regularly recurrent.

Coordination (Selective)

Localization of an over-current condition to restrict outages to the circuit or equipment affected, accomplished by the selection and installation of over-current protective devices and their ratings or settings for the full range of available over-currents, from overload to the maximum available fault current, and for the full range of over-current protective device opening times associated with those over-currents.

Exposed as applied to wiring methods

On or attached to the surface or behind panels designed to allow access.

Duty, Short-Time

Operation at a substantially constant load for a short and definite, specified time.

Duty, Continuous

Operation at a substantially constant load for an indefinitely long time.

Duty, Varying

Operation at loads, and for intervals of time, both of which may be subject to wide variation.

Duty, Intermittent

Operation for alternate intervals of (1) load and no load; or (2) load and rest; or (3) load, no load, and rest.

Automatic

Performing a function without the necessity of human intervention.

Adjustable Speed Drive

Power conversion equipment that provides a means of adjusting the speed of an electric motor.

Electric Power Production and Distribution Network

Power production, distribution, and utilization equipment and facilities, such as electric utility systems that deliver electric power to the connected loads, that are external to and not controlled by an interactive system.

Concealed

Rendered inaccessible by the structure of finish of the building.

Enclosed

Surrounded by a case, housing, fence, or wall(s) that prevents persons from accidentally contacting energized parts.

Electric-Discharge Lighting

Systems of illumination utilizing fluorescent lamps, high-intensity discharge (HID) lamps, or neon tubing.

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 over-current device protecting the circuit and the outlet(s).

Control Circuit

The circuit of a control apparatus or system that carries the electric signals directing the performance of the controller but does not carry the main power current.

Grounding Conductor, Equipment (EGC)

The conductive path(s) that provides 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.

Bonding Jumper, Main

The connection between the grounded circuit conductor and the equipment grounding conductor at the service.

Bonding Jumper, System

The connection between the grounded circuit conductor and the supply side bonding jumper, or the equipment grounding conductor, or both at a separately derived system.

Bonding Jumper, Equipment

The connection between two or more portions of the equipment grounding conductor.

Ground

The earth.

Communications Equipment

The electronic equipment that performs the telecommunications operations for the transmission of audio, video, and data, and includes power equipment

Ampacity

The maximum current in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.

Demand Factor

The ratio of the maximum demand of a system, or part of a system, to the total connected load of a system or the part of the system under consideration.

Appliance

Utilization equipment, generally other than industrial, that is normally built in standardized sizes or types and is installed or connected as a unit to perform one or more functions such as clothes washing, air-conditioning, food mixing, deep frying, and so forth.

Dead front

Without live parts exposed to a person on the operating side of the equipment.