KY Electrician key terms

The organization, office, or individual responsible for enforcing the code and approving equipment, materials, and installations. In Kentucky this is usually a state or local electrical inspector.

Equipment or material that a nationally recognized testing laboratory has evaluated to a designated standard and included on a published list of certified products.

Acceptable to the authority having jurisdiction. Approval may rest on listing, labeling, or field evaluation and means the AHJ judges the item suitable for its intended use.

Written consent from the authority having jurisdiction allowing an installation the code otherwise prohibits or restricts. It must be obtained in writing before the work begins.

A factory-assembled cable containing two or more insulated conductors and a bare ground in an overall nonmetallic sheath, used mainly in dry, protected interior locations such as dwellings.

Thin-wall, unthreaded steel or aluminum raceway joined with couplings and connectors, used for exposed and concealed wiring in dry and damp locations; not permitted where severe corrosion or damage is likely.

Heavy-wall threaded metal raceway used indoors and outdoors, including hazardous locations and areas subject to corrosion or physical damage; it can serve as an equipment grounding conductor when installed properly.

A structural system of rails and rungs used to support and route cables, conductors, and raceways. Cables must be secured, and the tray must be bonded and grounded.

The conductive path, usually a bare or green conductor, connecting metal equipment parts to the grounding system so fault current can return and open the overcurrent device.

The rod, pipe, plate, or other electrode in direct contact with the earth, together with the conductors connecting it to the service, establishing a reference to earth potential.

The connection in service equipment between the equipment grounding conductor and the grounded service conductor, tying the metal enclosure and grounding path to the neutral and electrode system.

The permanent joining of metal parts to form an electrically conductive path that ensures electrical continuity and can safely carry any current likely to be imposed.

A wiring system whose power comes from a transformer, generator, or converter with no direct connection, including a neutral, to the supply conductors; it is grounded and bonded at its source.

The maximum current, in amperes, a conductor can carry continuously under its conditions of use without exceeding its temperature rating, after correction and adjustment factors are applied.

Any current greater than the rated ampacity of a conductor or the rating of equipment. It may result from overload, short circuit, or ground fault.

A load whose maximum current is expected to continue for three hours or more. Conductors and overcurrent devices serving it are generally sized at 125 percent of the load.

Percentages applied to conductor ampacity when more than three current-carrying conductors share a raceway or cable, or when ambient temperature differs from the table's base conditions.

The maximum short-circuit current a component or assembly can safely withstand without damage. Equipment must be rated at least equal to the available fault current at its terminals.

The ratio of the maximum demand of a system, or part of it, to the total connected load. It allows conductors and equipment to be sized smaller than the sum of all loads.

The circuit conductors between the final overcurrent device protecting the circuit and the outlets it serves, such as receptacles, luminaires, or appliances.

All circuit conductors between the service equipment, a separately derived source, or another supply and the final branch-circuit overcurrent device.

The required internal volume of an outlet, junction, or device box, calculated from the number and size of conductors, devices, fittings, and equipment grounds it contains.

The limit on how much of a raceway's cross-sectional area conductors may occupy, typically 40 percent for three or more conductors, so they can be pulled without damage.

A device that de-energizes a circuit within a set time when current to ground exceeds a few milliamperes, protecting people from shock in bathrooms, kitchens, outdoors, and similar areas.

A device that detects the signature of an arcing fault in branch-circuit wiring and opens the circuit, reducing fire risk; required for many dwelling-unit branch circuits.

A connection from a feeder to a smaller conductor without a branch-circuit overcurrent device at the tap point, permitted only within specific length and ampacity limits.

A switch or device, or group of them, by which the conductors of a circuit can be disconnected from their source of supply; it must be readily accessible and marked.

A device that protects a motor from overheating caused by excessive current over time, sized to the motor nameplate and set to trip at a percentage of full-load current.

A device or group of devices that governs the power delivered to a motor in a predetermined way, starting and stopping it; it may be manual or remote.

Equipment that uses electrical energy for mechanical, chemical, heating, lighting, or similar purposes, such as appliances, motors, and luminaires; it is the load end of a circuit.

A hazardous location where ignitable vapors or gases may exist under normal conditions, or frequently because of repair or leakage, requiring explosionproof wiring methods and equipment.

A circuit designed so any spark or thermal effect it produces cannot ignite a flammable mixture, generally by limiting voltage and current; its wiring is often kept separate and identified.

A circuit supplied from a listed source with limited power and voltage, such as for controls, thermostats, or communications, allowing lighter wiring because fire and shock risk is low.

Cable whose jacket and insulation are listed for use in air-handling spaces, giving off limited smoke and flame when burned; required when cable is run in a plenum ceiling.

The clear area in front of electrical equipment, defined by depth, width, and height, kept unobstructed so a person can work safely; depth depends on voltage and conditions.

A procedure for de-energizing equipment, applying a lock and tag, and verifying the absence of voltage before work, preventing accidental re-energization by others.

A dangerous condition in which an electric arc can release intense heat, light, and pressure; workers must use required personal protective equipment and safe work practices.

Legally required circuits and equipment supplying lighting, alarms, and other life-safety loads during a power outage; the system must be independent and tested periodically.