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Accessible
When referring to wiring methods:
Capable of being removed or exposed without damaging the building
structure or finish, or not permanently closed in by the structure or
finish of the building.
When referring to equipment: Admitting close approach:
not guarded by locked doors, elevation, or other effective means. (see
Accessible, Readily)
Accessible (Readily)
Readily Accessible means that it is capable of
being reached quickly for operation, renewal, or inspections, without
requiring those to whom ready access is requisite to climb over or
remove obstacles or to resort to portable ladders, chairs, etc.
Alternating Current
(AC)
Electric current
which changes direction with a regular frequency. Typically
frequencies in US 60 Hertz and Europe 50 Hertz
Alternator
An electric
generator designed to produce an alternating current. Usually
consists of rotating parts which create a changing magnetic field to
produce the alternating current.
Ambient
Temperature
The temperature of the air,
water, or surrounding earth. Conductor ampacity is corrected for changes
in ambient temperature including temperatures below 86°F. The cooling
effect can increase the current carrying capacity of the conductor.
(Review Section 310-10 of the Electrical Code for more understanding)
Ammeter
An instrument used to measure current
(amount of electron flow),
calibrated in amperes.
Ampacity
The current-carrying capacity of conductors or
equipment, expressed in amperes.
Ampere
The basic unit of electrical current.
Amplifier
A device used to increase the signal
voltage, current, or power, generally composed of a vacuum tube and
associated circuit called a stage. It may contain several stages in
order to obtain the desired gain.
Amplitude
The maximum instantaneous value of an
alternating voltage or current, measured in either the positive or
negative direction.
Analog
A measuring or display methodology
which uses continuously varying physical parameters. In contrast,
digital represents information in discrete binary form using only zeros
and ones.
Anodizing
Any electrolytic or chemical process by which a protective or
decorative film is released on a metal surface.
Apparent Power
The product of voltage and current in a circuit.
Arc
A flash caused by an electric current
ionizing a gas or vapor.
Sparking that results when undesirable current flows
between two points of differing potential. This may be due to leakage
through the intermediate insulation or a leakage path due to
contamination.
Armature
The rotating part of an electric
motor or generator. The moving part of a relay or vibrator.
Armature Coil
A winding that develops current output from a
generator when its turns cut a magnetic flux.
Arrester
A nonlinear device to limit the amplitude of voltage on a power
line. The term implies that the device stops overvoltage problems (i.e.
lightning). In actuality, voltage clamp levels, response times and
installation determine how much voltage can be removed by the operation
of an arrester.
Asymmetric
Unequal distribution about one or more axes.
Attenuator
A network of resistors used to reduce
voltage, current, or power delivered to a load.
Attenuation
The reduction of a signal from one point to another.
For an electrical surge, attenuation refers to the reduction of an
incoming surge by a limiter (attenuator). Wire resistance, arresters,
power conditioners attenuate surges to varying degrees.
AWG
American Wire Gage. This term refers to the U.S.
standard for wire size.
Autotransformer
A transformer used to step voltage up or down. The
primary and secondary are connected together in one winding, and it provides no
isolation.
Auxiliary Source
A power source dedicated to providing emergency power to a critical load when commercial power is interrupted. |
