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Ampacity Charts


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.

The number and type of electrical devices connected to a circuit determine the ampacity requirement of the conductor. Usually, a general-purpose house circuit is designed for 20 amps.

Lighting circuits may be designed for only 15 amps

To calculate the load requirement for a circuit, first add up the wattage of all the electrical devices that will be on the circuit.

Then, divide the total wattage by the voltage of the system, typically 120 or 240, and that will give you the required current or amps.

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