How to Choose a Circuit Breaker

Considerations with respect to input characteristics

Executive Summary

Circuit breakers can be considered the first line of defense for protecting a system from prolonged damage due to a short circuit or other destructive event. This paper will discuss about the important considerations when selecting a circuit breaker. These considerations include type, application, form factor, derating factors, regulatory standards, short circuit current rating and a step by step selection procedure and example.


Circuit breakers are electrical switches designed to protect a circuit from excess current caused by an overload or short circuit condition. When selecting a circuit breaker, one must consider the circuit to be protected. Is a branch circuit breaker or supplemental protector needed? The type of circuit breaker used depends on the trip time and application. What are your size and space constraints ie. what form factor is acceptable? Is the trip rating and short circuit current rating adequate for your application?

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