NEC Definitions 3

Device

A unit of an electrical system, other than a conductor, that carries or controls electric energy as its principal function

Transfer Switch

An automatic or nonautomatic device for transferring one or more load conductor connections from one power source to another

Circuit Breaker

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

Controller

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

Disconnecting Means

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

General Use Snap Switch

A form of general-use switch constructed so that it can be installed in device boxes or on box covers, or otherwise used in conjunction with wiring systems recognized by this code

Switchboard

A large single panel, frame, or assembly of panels on which are mounted on the face, back, or both, switches, overcurrent and other protective devices, buses, and usually instruments. These assemblies are generally accessible from the rear as well as from the front and are not intended to be installed in cabinets

Instantaneous Trip Circuit Breaker

A qualifying term indicating that no delay is purposely introduced in the tripping action of the circuit breaker

Inverse Time Circuit Breaker

A qualifying term indicating that there is a purposefully introduced delay in the tripping action of the circuit, which delay decreases as the magnitude of the current increases

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 that is capable of interrupting the maximum operating overload current of a motor of the same horsepower rating of the switch at the rated voltage

Switchgear

An assembly enclosed on all sides and top with sheet metal (except for ventilated openings and inspection windows) and containing primary power circuit switching, interrupting devices, or both, with buses and connections. The assembly may include control and auxiliary devices. Access to the interior of the enclosure is provided by doors, removable covers, or both.