Ground Fault Circuit Interupters

A GFCI is an inexpensive ($20 each),switch-like device that continuously monitors current in the hot and neutral conductors. When it detects an imbalance between the two, as would occur if there were a short to ground, it instantly trips the circuit. A single GFCI can protect persons throughout the boat if it is located on the main AC feed, but because boats usually have various small current leaks, the unit may trip frequently with no indication of the source of the fault. It may be more practical to install one GFCI on each of the circuits to wet locations, such as head, galley, engine room, and weather deck. GFCIs are extremely sensitive and can be tripped by “steam” or dense moisture in the air such as from cooking or showering, so they should be mounted in dry locations. On gas-powered boats, GFCIs must be ignition protected, or located in areas where fumes cannot collect. GFCIs should be checked at least monthly.