Electric Shock Drowning
A Little Understood Hazard at Freshwater Boat Docks
By Bob Adriance
Conscientious parents, who would never image letting their children go boating without a life vest or ride in a car without securing their seat belts, often have no qualms about letting them jump off of a dock into fresh water. What these parents don't realize is that 120-volt AC electricity that finds its way into the water from faulty wiring on the dock or a boat will be fatal to anyone in the water. In a one-week period this past July, there were four children and one young adult who were killed in separate electric shock drowning (ESD) incidents at docks on freshwater lakes.
• At a marina on Cherokee Lake in Tennessee, a 10-year old boy died instantly and his 11-year-old friend was critically injured and died the following day after swimming near a docked houseboat. Frayed wiring near a metal swim ladder on the houseboat was believed to have been the cause. Five adults who tried to rescue the boys were also affected and there likely would have been more fatalities had someone on the dock not had the presence of mind to disconnect the houseboat’s shore power cord.
• At Dry Branch Cove on Lake of the Ozarks, a 26-year old woman was electrocuted and died while swimming from a private dock that, according to preliminary police reports, had faulty wiring. Her two half brothers, ages 11 and 13, felt a tingling and were saved when they swam toward a different dock.
• In a separate Lake of the Ozarks incident, an eight-year-old boy and his 13-year-old sister both died while swimming from a dock that was also reported to have “improper wiring.”
A test of 50 freshwater boats in the Portland, Oregon area by Kevin Ritz, the nation’s foremost expert on ESD, found that 13 boats—26 percent—were leaking potentially lethal doses of electricity into the water. How much electricity is lethal? An AC current flow of around 100 mA will put the heart into fibrillation, and death will likely follow within seconds. But lesser amounts of electricity, say 15 to 30 milliamps (mA) of AC current, will create muscle paralysis, and even the best swimmers will be drowned. Note that most local law enforcement investigators don’t have the technical background to recognize an ESD accident and there is no post-mortem evidence available to coroners to ascertain whether electricity was involved in a drowning. It is highly likely that there are many “drowning” victims who were actually electrocuted.
When ESD accident are identified, the parents and friends of the victims are almost always unaware that swimming from an energized dock was dangerous. In many past ESD cases, bystanders who dove into the water to save children also became victims.
To protect against ESD accidents, the American Boat & Yacht Council (ABYC) E-11 adopted standards in 2010 that requires an Equipment Leakage Circuit Interrupter (ELCI) be installed on new boats. However, not all boat manufacturers follow the ABYC standards, which are voluntary, and there is no requirement to retrofit ELCIs on older boats. There is also no standard that would requires the installation of Ground Fault Circuit Interrupters (GFCIs) at marinas and private docks. (Note that in Europe, GFCIs have been required at marinas for almost 30 years and ESD is no longer a concern.) Until such time as freshwater boats and docks are safe—and that could be decades away--the best defense is to NEVER SWIM NEAR DOCKS WITH ENERGIZED 120 VOLT AC POWER. Signs should be posted warning children and parent to Stay Out Of The Water! The rule has to be enforced. If someone must to go into the water to retrieve something lost overboard, the electricity to the dock should be shut off.
Note that 12-volt electricity will not cause ESD. Nor will 120-volt current from a generator unless another boat (with an electrical fault) is sharing electricity from the generator via a power cord. In saltwater, electricity does not cause ESD; saltwater is more conductive than the human body. There is not yet enough research to know at what point brackish water becomes dangerous. When in doubt, stay out.
Bob Adriance is Editor of Seaworthy, the BoatUS Marine Insurance Program damage-avoidance publication, which is free to all BoatUS insureds. For an insurance quote, please call 1-800-283-2883 or apply online at BoatUS.com