Function

Circuit breakers are used to detect fault conditions -- abnormal conditions that can lead to circuit failure. Once detected, the breaker stops electrical flow by interrupting the circuit continuity. This protects the circuits from short circuits or overloads.

Wear

Circuit breakers can wear out for numerous reasons, such as an overloaded circuit or weak components in the circuit breaker, such as the compressor or capacitor. Worn out circuit breakers are subject to constant tripping or will constantly turning themselves off, resulting in partial or total loss of power.

Testing

You can tell if a circuit breaker is worn out by turning off the breaker and removing it. You can then reset it to On and use an ohmmeter to check it by placing it between the circuit breaker's bus-clip and screw. If the circuit breaker reads higher than 5 ohms, it is worn out or otherwise faulty and in need of replacement.