Tag Archives: NEC

Marina Ground Fault Protection

marina_powerIn 2011, article 555.3 of the National Electric Code added a requirement for ground fault protection in marinas. The purpose of this requirement is to protect the public from ESD, or Electric Shock Drownings, of which there have been more than 100 reported cases in the US. It is likely that many more have actually occurred, but were misidentified as conventional drownings. ESD occurs when ground faults in marina wiring or more commonly, on connected boats cause return current through the water. Even relatively small currents through the water can set up steep voltage gradients, which have the effect of paralyzing swimmers in the vicinity, who consequently drown. Tragically, some cases involve multiple drownings because an onlooker sees a swimmer in distress, and unaware of the danger in the water, jumps in with intent to save the victim, but instead immediately becomes paralyzed and perishes along with the first victim.

The requirement continues to be misunderstood by the boating community, marina owners, and contractors. Myths abound such as that the higher current settings of 100mA do not protect people, or that nuisance tripping is impossible to prevent. The fact is that a very large number of boats have ground faults on them, which have gone undetected for years. When the ground fault detection circuit activates because a boat shows up and plugs in, this generally means the system is working, but users often conclude just the opposite is true because “my boat has been fine for 20 years and now this new system says there’s a problem?” Well, lets just say it’s a good thing no one swimming around that boat.

Please contact us for concerns about electric shock drowning, ground fault protection, or electrical code compliance in marinas.

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