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Electrical Code Terminology


Summary: Electrical Code Terminology as it pertains to a Qualified Person who may perform home electrical wiring.

Understanding the Terminology used with Home Electrical Codes

Understanding Electrical Code Terminology


ACCESSIBLE: (As applied to equipment) Admitting close approach: not guarded by locked doors, elevation or other effective means.

ACCESSIBLE: (As applied to wiring methods) Capable of being removed or exposed without damaging the building.

ACCESSIBLE, READILY: (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.

Code Adoption Information: The codes shown are examples only and may not be current or accurate for your application or jurisdiction. Contact your local building authority for complete information.


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

APPLIANCE: An appliance is utilization equipment, generally other than industrial, normally built in standardized sizes or types, which is installed or connected as a unit to perform one or more functions such as clothes washing, air conditioning, food mixing, deep frying, etc.

APPROVED: Acceptable to the authority having jurisdiction. The phrase authority having jurisdiction is used in NFPA documents in a broad manner since jurisdictions and "approval" agencies vary, as do their responsibilities. Where public safety is primary, the authority having jurisdiction may be a federal, state, local, or other regional department or individual such as a fire chief, fire marshal, chief of a fire prevention bureau, labor department, health department, building official, electrical inspector, or others having statutory authority. For insurance purposes, an insurance inspection department, rating bureau, or other insurance company representative may be the authority having jurisdiction. In many circumstances the property owner or the owner's designated agent assumes the role of the authority having jurisdiction; at government installations, the commanding officer or departmental official may be the authority having jurisdiction.

AUTOMATIC: Self-acting, operating by its own mechanism when actuated by some impersonal influence, as for example, a change in current , pressure, temperature, or mechanical configuration.

BRANCH CIRCUIT: The circuit conductors between the final over current device protecting the circuit and the outlet(s).

BRANCH CIRCUIT, APPLIANCE: A branch circuit supplying energy to one or more outlets to which appliances are to be connected; such circuits to have no permanently connected lighting fixtures not a part of an appliance. Appliance branch circuits for a kitchen, pantry, etc. and for laundry areas are not permitted to have any other outlets or permanently connected lighting fixtures connected to them.

BRANCH CIRCUIT, GENERAL PURPOSE: A branch circuit that supplies two or more receptacles or outlets for lighting and appliances.

BRANCH CIRCUIT, INDIVIDUAL: A branch circuit that supplies only one utilization equipment. An individual branch circuit shall be permitted to supply any load for which it is rated: for example, one range, or one space heater, or one motor. NEC 210-23 A branch circuit may be installed to supply one duplex receptacle, which can accommodate two cord-connected and plug-connected appliances or similar equipment. This circuit would not be considered an individual branch circuit.

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.

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.

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.

CONTINUOUS LOAD: A load where the maximum current is expected to continue for three hours or more.

CONTROLLER: A device or group of devices that serves to govern, in some predetermined manner, the electrical power delivered to the apparatus to which it is connected.

DEVICE: A unit of an electric system that is intended to carry or control ,but not utilize, electrical energy. Units, such as switches,circuit breakers, fuse holders, receptacles, attachment plugs, and lamp holders that distribute or control but do not consume electricity are termed devices.

DISCONNECTING MEANS: A device, group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply.

DWELLING: 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. One Family Dwelling: A building consisting solely of one dwelling unit.

Two Family Dwelling: A building consisting solely of two dwelling units. Multifamily Dwelling: A building containing three or more dwelling units. ENCLOSED: Surrounded by a case, housing, fence, or walls that prevents persons from accidentally contacting energized parts.

EQUIPMENT: A general term including material, fittings, devices,appliances, luminaries (fixtures), apparatus, and the like used as a part of, or in connection with, an electrical installation

Home Electrical Codes

EXPOSED: (As applied to wiring methods) On or attached to the surface or behind panels designed to allow access.

FEEDER: All circuit conductors between the service equipment or the source of separately derived system or other power supply source and the final branch-circuit overcorrect device.

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 non-current-carrying metal parts of equipment,raceways, and other enclosures to the system grounded conductor, the grounding electrode conductor, or both at the service equipment or at the source of a separately derived system.

IDENTIFIED: (As applied to equipment) Recognizable as suitable for the specific purpose, function, use, environment, application, etc., where described in a particular Code requirement.

LOCATION: 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, some barns and some cold-storage warehouses.

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. 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 locations exposed to weather and unprotected.

OUTLET: A point on the wiring system at which current is taken to supply utilization equipment.

RACEWAY: An enclosed channel designed expressly for holding wires, cables, or bus bars, with additional functions as permitted in this Code. Raceways may be of metal or nonmetallic materials. Raceways include, but are not limited to, rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquid tight flexible conduit, flexible metallic tubing, flexible metal conduit,electrical nonmetallic tubing, electrical metallic tubing, under floor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wire ways, and bus ways.

RAINTIGHT: Constructed or protected so that exposure to a beating rain will not result in the entrance of water under specified test conditions.

RECEPTACLE: A receptacle is a contact device installed at the outlet for the connection of an attachment plug. 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 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, 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 the supply.

SPECIAL PERMISSION: The written consent of the authority having jurisdiction.

SWITCHES: 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. 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. Weatherproof: Constructed or protected so that exposure to the weather will not interfere with successful operation. Rainproof, rain tight, 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.

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.

Weatherproof: Constructed or protected so that exposure to the weather will not interfere with successful operation. Rainproof, rain tight, 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.

Always contact your local building authority for complete and up to date code information.

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