Ampacity

OSHA defines ampacity as the current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. The CPSC says an overload happens when the load on a circuit goes above the ampacity of its conductors. Wire size, insulation and heat all affect the number.

A circuit breaker is chosen to protect the wire, so the breaker rating must not exceed the wire's ampacity. See wire gauge for sizes. A larger breaker on small wire is a fire risk. Ask a licensed electrician. See the home electrical safety checklist.