Onboard Circuits

When the boat is afloat, inverters and gensets are grounded to the water via the engine and shaft, which act like the metal rod driven into the ground under your house. The risk aboard a boat comes from a short that bypasses the grounding system and finds an alternative route to the sea. Standing in bilge water or touching a metal object like rudder stock or engine block, while contacting a hot wire, could make you the conductor if there is no functional grounding wire. Shore power presents a different set of potential problems. The shore power circuit is grounded at the dock junction box through the shore power cord and receptacle. Faulty installation, reversed polarity, defective or damaged cord or boat receptacle can create a situation that could be hazardous to persons or contribute to stray current corrosion damage to the boat.