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How many faults can a breaker interrupt?

This is a summary of what breakers do for UL489: requirements vary, so please refer to the UL489 for complete details.

The circuit breaker is operated making and breaking 600% of its continuous current rating, but not
less than 150 ampere.
For circuit breakers through 1600 ampere, the number of 600% operations is 50. For larger circuit
breakers to 4000 ampere, the number of operations is 25.

Short Circuit (typically around 10 to 12 times handle rating)
For circuit breakers rated 240 Vac and higher, two short circuit tests per pole and one test with all
poles connected in series is performed. For example, a 3-pole circuit breaker receives seven short
circuit tests.

High Available Fault Current Tests (twice at interrupting rating)
After qualifying a set of circuit breakers to the standard tests, a manufacturer can have additional
circuit breaker samples tested on higher than standard available fault currents.

CTA-ID : 2034155
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