ESD – Electric Shock Drowning

By Andrew Spaulding

Last week 3 technicians and 2 managers (me included) from Crowley’s attended a 4-day training class that, in part, discussed ESD – Electric Shock Drowning. I was as ignorant as anyone about this issue. I had heard of electrocution in marinas, but didn’t figure that I needed to worry about it since it always happens somewhere else. Well, we know how that can go.  After class, it occurred to me that we need to raise awareness about this issue here in Chicago so that we don’t have to deal with losing a member of our boating community from very preventable ESD.

Basically, ESD is water-related electrocution. In many cases of death by ESD, the victim is dead from electrocution before they have a chance to drown. Over the last three years, the number of reported cases of ESD has risen dramatically due to increased awareness of the issue. Prior to this increased awareness, the victims were regarded simply as drowning victims. It takes over 3 amps to run a small hair dryer on the low setting (400 watts), but less than 1 amp to electrocute a person in the water.

ESD only happens in fresh water. In salt water, the water is much more conductive which allows the electricity to dissipate rapidly. In fresh water, the water is less conductive which forces the electricity into a narrow path as it travels back to its source. For ESD to occur, two failures need to happen: one in the grounding system and one in the electrical system. Thank goodness this is fairly rare; however, a random check in 3 fresh water marinas in Portland, OR showed that 13% of the boats tested were leaking potentially deadly voltage.

Physical results from entering an area where there is voltage in the water vary from tingling sensations caused by 1-3 milliamps (mA), to heart defibrillation caused by 50-65 mA. Over 100 mA causes death in a few seconds and current over 200 mA is immediate cardiac arrest. There are 1000 mA in an amp and remember that a small hairdryer will used 3 amps or 3000 milliamps! You wouldn’t take a hairdryer near the bathtub while you are in it, but a boat is exactly that. If you are swimming around boats that are plugged into shore power or have generators running and you feel tingling, as best as possible scrunch into a ball and return the way you came to that area of the water. It is critical to remember that often the closest “safe haven” (swim platform or ladder) is the boat that is causing the problem.

What steps do we take to minimize the potential for ESD? On the dockside, we need to make sure the docks are wired to national codes (NFPA and NEC). On the boat, make sure that the wiring is to ABYC standards. On both sides, the wiring needs to maintain proper polarity and the resistance in the wiring should be less than 1 amp. Regular testing and inspection of the wiring is a key factor in preventing ESD. Also, all outlets on the dock and select ones in the boat should have GFCI (Ground Fault Circuit Interrupter) protection. As of 2010, all new boats are required to have ELCI (Equipment Leakage Circuit Interrupter) protection. Ask your qualified marine electrician to look at installing an ELCI on your boat the next time you are in for service. For the ultimate in protection, investigate installing an isolation transformer.

Please let us know if you have any questions about ESD or other marine related electrical issues. If you are going to take a multi-meter and do some testing on your own, be safe and use a clamp-type ammeter. Remember that to be accurate all electrical testing needs a good ground.