A conducting connection between an electric circuit or device and the earth or other point of zero potential

The main disconnect for the entire electrical system of a building, except for any emergency power systems

A board on which are mounted the switches, fuses, and circuit breakers for controlling and protecting a umber of similar branch circuits, installed in a cabinet and accessible from the front only

A heavy conductor, usually in the form of a solid copper bar, used for collecting, carrying, and distributing large electric currents

Any conductor of an electrical system intentionally connected to a ground connection

Any conductor of an electrical system intentionally connected to a ground connection

A conductor connecting electric equipment or a circuit to a ground connection

Of or pertaining to a circuit energized by an alternating current with one phase or with phases differing by 180°

Of or pertaining to a circuit energized by two alternating currents or voltages differing in phase by one quarter of a cycle or 90°

Of or pertaining to a combination of three circuits energized by alternating currents or voltages differing in phase by one third of a cycle or 120°

Electrically connected to a source of voltage, or electrically charged so as to have a potential different from that of earth

Not electrically connected to a source of voltage

Not electrically charged

A local failure in the installation or continuity of a conductor, or in the functioning of an electrical system

An abnormal, usually accidental condition of low resistance between two points in an electric circuit, resulting in a flow of excess current

The muscular spasms caused by an electric current passing through the body

A device containing a strip or wire of fusible metal that melts under the heat produced by excess current, thereby interrupting the circuit

Any of various metal alloys having a melting point below 70°C, used as solder and in various safety devices

A fuse housing a fusible link in a porcelain cup fitted with a threaded metal base

A fuse having a one-time or renewable fusible link enclosed in an insulating fiber tube

A cartridge fuse having a metal blade at each end for making contact with the fusible link within

A fuse that delays opening to allow a short-term overload to pass, as when starting a motor

A momentary, usually accidental, grounding of a conducting wire

A circuit breaker that senses currents caused by ground faults and instantaneously shuts of power before damage or injury can occur

A panel for distributing power to other panels or to motors and other heavy power-consuming loads

Or of pertaining to a circuit in which alternating current below 50 volts is supplied by a step-down transformer from the normal line of voltage, used in residential systems to control doorbells, intercoms, heating and cooling systems, and remote lighting fixtures. These do not require a protective raceway.

Any of several conducting rods installed at the top of a structure and grounded to divert lightning away from the structure

A device for protecting electric equipment from damage by lightning or other high-voltage currents, using spark gaps to carry the current to the ground without passing through the device

A space between two terminals or electrodes, across which a discharge of electricity may pass at a prescribed voltage

The portion of an electrical system extending from the final over-current device protecting a circuit to the outlets served by the circuit

A branch circuit that supplies current to a number of outlets for lighting and appliances

A branch circuit that supplies current to one or more outlets specifically intended for appliances

A branch circuit that supplies current only to a single piece of electrical equipment