Ambient Temperature Rating

Temperature at which the continuous current
rating (handle rating) of a circuit is based; the
temperature of the air immediately surrounding
the circuit breaker that can affect the thermal
(overload) tripping characteristics of a thermalmagnetic
circuit breaker. Electronic trip circuit
breakers, however, are insensitive to normal (-
5o to 50o C) ambient conditions. UL standard
489 listed circuit breakers have an ambient
temperature rating of 40o C.

Ambient Temperature

Temperature of the surrounding atmosphere
into which the heat of any electrical product is
dissipated.

Ambient Noise Level

The noise level of the surrounding area
measured in decibels.

Alternating current

This is the most common type of current used
today. In the United States, all electricity is
generated as alternating current. It is called
alternating current because first the current
flows in one direction then it will flow in the
opposite direction and so on. The current
alternates between two opposite directions. (It is
often represented by a side-ways “s”) Alternating
current is used in homes for lighting, heating,
cooking, and operating appliances. Industry
uses it primarily to operate motors but also for
lighting and equipment operation. The
abbreviation for alternating current is “AC”.

AIR Ampere Interrupting rating

Ampere Interrupting rating. The highest current
at rated voltage that a circuit breaker is intended
to interrupt under standard test conditions.