Matching Wire Size to Circuit Amperage

Wire Gauge and Ampacity

Whenever a circuit is extended or rewired, or when any new circuit is installed, it is critical that the new wiring is made with wire conductors that are properly sized for the amperage rating of the circuit. The higher the amperage rating of the circuit, the larger the wires need to be in order to avoid excess heat that can melt wires and cause fires. The proper circuit size, as indicated by amperage, is determined by several factors, including the planned load on the circuit, the number of outlets or light fixtures, and the length of the circuit. Once the proper amperage is determined, though, it is critical, that the wire gauge used in the circuit is appropriate for the amperage of the circuit breaker.