Marine Electrical Systems USCG Question #389 (Set 13)

When testing for blown fuses in a three-phase supply circuit to a motor, what would be an acceptable method?

Official USCG Answer & Rule Citation

Correct Answer: Option A — apply a voltage tester diagonally across the tops of the fuses and the bottoms of the other fuses

Checking energized circuits safely or testing de-energized fuses diagonally identifies voltage drops across blown fuses while accounting for multi-phase supply paths.

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