Name:   Astro - Subject:   How to FIX Boat Dock Shock Date:   7/8/2016 2:10:38 PM

Having worked for a power company for many years and dealing with this type problem I will express my thoughts.  Treating dock wiring as if it is an extension cord solves the problem.  People are normally getting shocked when the house ground is connected to the dock and that creates a difference in potential between the dock metal and water.  Make sure that the bare ground does not contact any part of the metal.  A common problem is the boat lift motor.  The motor is grounded to the motor frame which in turn is usually attached directly to metal dock flooring.  You can check to see if this is the problem by putting a voltmeter probe into the water and the other touching the metal on the dock, then uplug the hoist and you should see the voltage disappear if that is the only place where the ground is touching metal.  In every case I have worked on it was never the 120 volts energizing the dock but the ground potential difference.  Other post encouraging GFI breakers is spot on and should never be disconnected.  GFI breakers will protect if the live circuit becomes shorted but does not protect the ground potential problem.