WA Electrician key terms

The maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Ampacity is used to size conductors and the overcurrent devices that protect them.

Any current in excess of the rated current of equipment or the ampacity of a conductor. It may result from an overload, a short circuit, or a ground fault.

An unintentional electrical connection between an ungrounded conductor and normally non-current-carrying metal parts, the earth, or grounded circuit conductors. It is the condition GFCI devices are designed to detect.

The permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity and the capacity to conduct safely any current likely to be imposed on it.

The conductive path installed to connect normally non-current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both.

The conductor used to connect the system grounded conductor or the equipment to a grounding electrode, or to a point on the grounding electrode system.

The relationship stating that current equals voltage divided by resistance (I = E/R) in a direct-current circuit. It underlies load calculations, voltage drop estimates, and circuit troubleshooting.

A unit of conductor cross-sectional area equal to the area of a circle one mil, or 0.001 inch, in diameter. It is used to compare conductor sizes and to calculate resistance.

A load where the maximum current is expected to continue for three hours or more. Branch-circuit conductors and overcurrent devices for continuous loads are generally sized at 125 percent of the load.

The ratio of the maximum demand of a system, or part of a system, to the total connected load on that system. It allows feeders and services to be sized smaller than the sum of every connected load.

The organization, office, or individual responsible for enforcing the code or approving equipment, materials, an installation, or a procedure. In Washington, local building officials and state electrical inspectors act as AHJs.

The loss of voltage along a circuit caused by conductor resistance and reactance. The Code recommends limiting the combined feeder and branch-circuit drop to about 5 percent for reasonable efficiency.

The Washington Administrative Code chapter that adopts the National Electrical Code with state amendments and sets installation, permitting, and inspection rules enforced by the Department of Labor and Industries.

The Washington statute covering electricians and electrical installations. It establishes electrician certification, electrical permits, inspections, and the authority under which the state electrical rules are written.

An enclosed channel of metal or nonmetallic material designed expressly for holding wires, cables, or busbars, with additional functions as permitted by the Code. Conduit and electrical tubing are common examples.

A factory assembly of two or more insulated conductors enclosed in an overall nonmetallic sheath. It is commonly used for dry interior wiring in dwellings and similar occupancies where the Code permits it.

The minimum volume an outlet, device, or junction box must have, calculated from the number and size of conductors, devices, fittings, and grounding conductors it contains, using the tables and rules in Article 314.

The maximum number of conductors allowed inside a raceway, based on conductor size and insulation and on raceway type. For three or more conductors the usual limit is 40 percent of the interior cross-sectional area.

Reducing a conductor's allowable current-carrying capacity to account for conditions of use, such as more than three current-carrying conductors in a raceway or higher-than-normal ambient temperature.

Code requirements for fastening raceways and cables at specified intervals and within a specified distance of boxes, panels, and terminations so the wiring stays securely in place.

A raceway fitting that lets a conduit run change length as the raceway expands and contracts with temperature, preventing damage to bends, couplings, and terminations.

An installation location subject to saturation with water or other liquids, such as an outdoor area exposed to weather, a concrete slab in contact with earth, or a washdown area. Equipment there must be listed for wet locations.

A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system. Wiring installed in a plenum must meet strict flame-spread and smoke-developed limits.

An area where a fire or explosion hazard may exist because of flammable gases, vapors, liquids, dusts, or fibers. Equipment installed there must be listed and marked for the specific class, division or zone, and group.

A system that supplies power to selected loads, such as a home or business, when the normal supply fails, where life safety is not the reason for providing the backup power.

A device that senses a difference between the current in the ungrounded and grounded conductors and quickly opens the circuit to protect people from shock. It is required in bathrooms, kitchens, outdoors, and other wet areas.

A device intended to detect and interrupt dangerous arcing faults in branch circuits, protecting against fires started by damaged or deteriorated wiring. It is required for most dwelling-unit branch circuits.

A contact device installed at an outlet for the connection of an attachment plug, such as a standard wall outlet. Receptacles are rated by voltage, amperage, and configuration.

The equipment, usually consisting of circuit breakers or switches and fuses with their accessories, connected to the load end of service conductors to a building. It is intended to be the main control and means of cutoff.

The current a motor draws at its rated horsepower, voltage, and frequency when operating at full load. It is taken from Code tables and used to size conductors, overload protection, and disconnecting means.

A device, such as a thermal overload relay, that protects the motor from damaging heating caused by a running overload or failure to start. It is sized according to the motor's service factor and temperature rise.

A switch or circuit breaker that isolates the motor and its controller from the power source. It must be readily accessible and within sight of the motor, and sized at not less than 115 percent of the motor full-load current.

A device or group of devices that governs, in a predetermined manner, the electric power delivered to the apparatus to which it is connected. A motor starter or contactor is a typical controller.

A safety procedure in which an energy-isolating device is locked and tagged so equipment cannot be re-energized while work is being done, protecting workers from unexpected energization or startup.

The sudden release of heat, light, and pressure caused by an electric arc between conductors or from a conductor to ground. It can cause severe burns, blast injury, and hearing damage.

A distance from an exposed energized conductor within which a person must use protective equipment or follow specific restrictions because of shock risk. It is divided into limited, restricted, and prohibited boundaries.

A person who has demonstrated skills and knowledge related to the construction and operation of electrical equipment and installations and has received safety training to recognize and avoid the hazards involved.

A documented authorization required before work is performed on or near energized electrical conductors. It records the justification, hazard analysis, shock and arc-flash risk, required PPE, and approval signatures.

The amount of thermal energy impressed on a surface a certain distance from an arc source, usually expressed in calories per square centimeter. It is used to select arc-rated clothing and other protective equipment.

Clothing and equipment such as arc-rated garments, hard hats, safety glasses, face shields, and insulating gloves worn to protect workers from electrical, thermal, and physical hazards on the job.