Single-Pole Short-Circuit Interruption of Molded-Case Circuit Breakers

Short-circuit tests of individual poles of molded-case circuit breakers are required under North American industry standards. Test current is intentionally at a limited fault availability level rather than at the interrupting rating of the circuit breaker. This paper clarifies the single-pole test requirements. It then examines the potential fault conditions under a variety of systems and provides application guidelines considering the potential fault conditions.