Common electrical terminology

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ampacity

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

ampere

A type of electric current produced by one volt applied across a resistance of one ohm. It is also equal to the flow of one coulomb per second. Named after French physicist Andre M. Ampère 1836.

branch circuit

The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s).

brownout

A reduction in voltage and/or power when demand for electricity exceeds generating capacity. The term brownout is misleading because customers generally do not notice the reduction, except when it affects sensitive electronic equipment.

buss bar

circuit breaker

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

circuit extensions

To extend or add-on to an existing circuit to provide an additional power source.

code corrections

Procedure designed to eliminate wiring conditions that do not meet National Electrical Code requirements and safety conditions.

continuous load

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

fault

A short circuit in an electrical system.

ground wire

A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and the earth, or to some conducting body that serves in place of the earth. Being grounded means connected to earth or to some conducting body that serves in place of the earth.

impedance

The total effects of a circuit that oppose the flow of an AC current consisting of inductance, capacitance, and resistance. It can be quantified in the units of ohms.

impulse

A current surge.

insulator

Any material which does not allow electrons to flow through it.

kilowatt (kW)

Real power delivered to a load (W x 1,000 VA).

kilowatt-hour:

A unit of energy or work equal to one kilowatt for one hour. Abbreviated as kwh or KWH. This is the normal quantity used for metering and billing electricity customers. The price for a kwh varies from approximately 4 cents to 15 cents. At a 100% conversion efficiency, one kwh is equivalent to about 4 fluid ounces of gasoline, 3/16 pound LP, 3 cubic feet natural gas, or 1/4 pound coal.

neutral

The junction point of the legs in a Wye circuit.

overload

Operation of equipment in excess of normal, full-load rating, or of a conductor in excess of rated ampacity that, when it persists for a sufficient length of time, would cause damage or dangerous overheating. A fault, such as a short circuit or ground fault, is not an overload.

phase

Classification of an AC circuit usually single-phase, two wire or three wire; two-phase, three wire or four wire; or three-phase, three wire or four wire.

power

The rate at which work is performed or that energy is transferred. Electric power is commonly measured in watts or kilowatts. A power of 746 watts is equivalent to 1 horsepower.

real power

The rate at which work is performed or that energy is transferred. Electric power is commonly measured in watts or kilowatts. The term real power is often used in place of the term power alone to differentiate from reactive power. Also called active power.

Romex

service panel

subpanel

transfer switch

An electronic device that under certain conditions will disconnect from one power source and connect to another power source.

volt

The electrical potential difference or pressure across a one ohm resistance carrying a current of one ampere. Named after Italian physicist Count Alessandro Volta 1745-1827.

volt ampere

A unit of apparent power equal to the mathematical product of a circuit voltage and amperes. Here, apparent power is in contrast to real power. On ac systems the voltage and current will not be in phase if reactive power is being transmitted. Usually abbreviated VA.

watt

A unit of power equal to the rate of work represented by a current of one ampere under a pressure of one volt. Named after the Scottish engineer James Watt, 1819.