Locating the specific boat with a fault may be done by clamping a sensitive AC ammeter on each shore cord in the group. "Water Path" current is displayed on boat with fault. We stock this meter and it will fit a 120/240, 50 A Cord. In this example a clamp-on AC ammeter would read 1A when encircling all three conductors in shore cord, L1 - N - Gnd. Displays water path current. (click to enlarge) An undetected AC ground fault which produces a water path current in salt water may not create enough current density to affect a swimmer, even with a defective bonding conductor (ground). Because of the much higher resistance of fresh water, however, the swimmer becomes the fault path conductor when the boat or dock ground is missing. A voltage rise will occur on the underwater gear of the affected boat and cause a paralyzing low level current to flow in the swimmer. Harbor Marine has cataloged over 115 "electric shock incidents" in marinas which have resulted in 42 fatalities (list available).   (click to enlarge) To continue reading more about Marina Guard click here