Marine Electrical Systems USCG Question #325 (Set 11)

By what means does a molded-case circuit breaker provide protection against short circuits?

Official USCG Answer & Rule Citation

Correct Answer: Option D — use of a magnetic trip unit

Molded-case circuit breakers utilize an electromagnetic trip unit, generating a strong magnetic field during high fault currents to instantly separate contacts. Per IEEE 45 and 46 CFR Subchapter J, this prevents catastrophic short-circuit damage.

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