What's With My Boat's Shore Power Wiring Colors? A reader recently sent in this photo from his boat showing the behind the scenes look at his shore power selector switch. His question has to do with whether or not the wiring color codes on his boat are compliant with regulations or industry standards. On a wishbone 4-Way connector the white wire is ground, yellow is left turn signal, yellow/brown is left side running lights, green is right turn signal, and green/brown is right side running lights. If there is a 5th pin then this most likely goes to an electric reverse lockout solenoid, typically found on boat trailers.
It consists of the green grounding wire in the AC wiring system and serves the purpose of preventing shocks or electrocution. The ground connection is usually made by clamping to a metal water pipe or by driving a long copper stake into the ground. On a boat, things are considerably more complicated. The green wire on the left is secured to the tank which appears to be plastic and if it is, is serving as a tank "bonding" wire and would typically go the filler neck if the boat has one. It would be more appropriate if the tank were metal. The green wire with the black stripe (white plastic insulator) is the sending unit ground. The green wire is a secondary, safety ground wire required by the USCG to provide a path to ground if there is an AC fault on the boat. Connecting this wire to the engine and DC negative on your boat will work great.