Ampacity is the maximum current that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Current is measured in amperes or “amps.” You must use the correct size wire for the current (load) requirement of the circuit to prevent the wire from overheating.

What determines ampacity of a wire?

The ampacity of the wire is determined by the amount of current in the wire at the point in which the conductor’s temperature rises 30°C. The ampacity rating of higher temperature rated wires is greater than lower temperature rated wires for any given size of conductor.

What does the amp rating on a cable mean?

This is a term for the maximum current carrying capacity, in amps, of a particular device. The current carrying capacity is normally associated with electrical cable and is determined as the maximum amount of current a cable can withstand before it heats beyond the maximum operating temperature.