How to Test Boat Wiring

Boats vary in their electrical complexity. Some have none at all, while others can have up to three power sources: battery, shore power plug in, and generator. Any boat owner with even the simplest of power sources fueling basic equipment should know how to ensure the wiring is in good condition, because while power makes boating easier, it is a very dangerous element in a water environment. Fortunately, it is simple to ensure the wiring on your boat is working properly.

• 1

  Test the battery power from each battery on board, using a voltmeter. Connect the red lead to the positive port on the battery, and the black lead to the negative/ground port. Connecting the wires to the appropriate ports is most important when testing DC wiring, but it is helpful to be consistent and do it with AC wiring as well. Voltage should read 12.5 volts for each battery.

• 2

  Insert a receptacle tester into each available outlet on the boat to get a readout on the AC power. Buy a receptacle tester capable of testing a reversed ground, a common problem in boats and a serious hazard. The resulting readouts are very straightforward. Each tester has three lights on the base of the unit that light up in various configurations. The specific patterns vary by maker, but the explanation of each result is printed on the tester so you can determine the meaning of the lights. Incorrect shore power wiring is a common problem at temporary docks and marinas with transient docking.

• 3

  Look for breaks in wires or frayed ends at connection points. Fix a break by first shutting off all power to the boat, both battery and shore power if applicable. Cut the wire completely if it is only partially severed. Strip the coating off of both ends and expose the wires inside. If the inner wire is solid, twist the two ends together. If the inner wire consists of two or three wires of different colors, twist the ends of corresponding colors together. Wrap a piece of shrinkable plastic around the exposed wires and use a heat gun or blow dryer to seal it. Disconnect power sources and remove frayed ends from any connection points. Cut the wire back to a place where the wire is not frayed, strip away the plastic coating and reconnect to the instruments, circuit breakers, or other connections they came from.