I went to a marina that has the standard power pedestals - A 30 and a 50 amp receptacle with feed thru circuit breakers controlling. Grounds were good, and showed no voltage from ground to water (salt water). The pedestals are a heavy duty plastic, held together with stainless screws. Each screw is only in contact with plastic. On the screws nearest the breakers: between screw and ground or screw and water I got anywhere from 20 to 100 volts AC. I grounded all the screws to the good grounds. Is this "induced" voltage, like a transformer? Anybody run into this before?