Accessible as Applied to Wiring Methods - Means:

• Not permanently closed in by the structure or finish of the building; and
• Capable of being removed without disturbing the building structure or finish.

Accessible as Applied to Equipment - Means admitting close approach because the equipment is not guarded by locked doors, elevation, or other effective means.

AL - Aluminum

Alive or Live - Means electrically connected to a source of voltage difference, or electrically charged so as to have a voltage different from that of the earth; and the term may be used in place of the term "current-carrying".

Aluminum-Sheathed Cable - A cable consisting of one or more conductors of approved type assembled into a core and covered with a liquid- and gas-tight sheath of aluminum or aluminum alloy.

Alternating Current (AC) - A flow of electricity which reaches maximum in one direction, decreases to zero, then reverses itself and reaches maximum in the opposite direction. The cycle is repeated continuously. The number of cycles per second is equal to the frequency.

Amalgam - A mixture of different elements.

Amalgamate - The forming of an amalgam; the union of two materials; an alloy.

Ambient Temperature - The temperature of the atmosphere of surrounding environment. Typically defined by industry standards as 25° C.

Ampacity - The current-carrying capacity of electric conductors expressed in amperes.

Ampere (A) - Unit of electrical current flow, or rate of flow of electrons.

ANSI - American National Standards Institute; Electrical standard developed and published as a result of recommended practices and studies made by NEMA and IEEE.

Arc - Sparking that results when undesired current flows between two points of differing potential.

Arc Voltage - The reaction of a circuit's inductance to the rate of current change in the circuit; E = L(di/dt); when a current-limiting fuse operates, there is an associated arc voltage on the system.

Arrester - A protective device for limiting surge voltages on equipment by diverting surge current and returning the device to its original status. It is capable of repeating these functions as specified.

Arrester Voltage Rating - RMS value of the maximum 60 Hz voltage to which an arrester should be subjected, even under transient conditions.

Arrestor - See Arrester

Asymmetric - A term used to explain the offset current waveform that can occur when a fault is initiated; the composite quantity of the transient current (dc component) and the steady state current (ac component); usually considered to be 1.6 times the symmetric for most electrical distribution systems.

Authorized Person - A qualified person who by the nature of their duties or occupation is obliged to approach or handle electrical equipment, or a person who, having been warned of the hazards involved, has been instructed or authorized to do so by someone having authority to give the instruction or authorization.

Auxiliary Gutter - A raceway consisting of a sheet metal enclosure used to supplement the wiring space of electrical equipment and to enclose interconnecting conductors.

AWG - The American (or Brown and Sharpe) Wire Gauge as applied to nonferrous conductors and nonferrous sheet metal.