Everyone knows about the danger of electric shocks. Likewise, we all take painsto teach our children to swim and use life preservers to prevent drowning. But most of us have never even heard of electric shock drowning.
As it turns out, electric shock drowning (ESD) can occur anywhere you have a boat, boathouse or dock supplied with 120 volt alternating current (AC) in fresh water. This is due to the relative conductivity of the human body versus fresh water. It can also occur if you have a boat that has 120 volt AC service. Boats with only 12 volt current cannot cause ESD.
An AC current flow of around 100 milliamps (mA) will send the heart into fibrillation and cause death, within seconds. But even very small amounts of current can create muscle paralysis which will lead to drowning, regardless of swimming ability. These small amounts of current can leak, undetected, into the water from faults in the electrical wiring of boats and boathouses. The chart on this page from the website of the Boat Owner’s Association of the United States (BoatU.S.) shows the probably effect of increasing levels of electric shock on the human body.
The problem appears to be greater around commercial or public marinas due to the number of boats connected to 120 volt outlets but there is still a danger associated with any structure that has 120 volt AC current. There have been over 100 confirmed cases of ESD but there may have been many more as the electricity in the water may go undetected and autopsies don’t reveal any evidence of the cause of death.
As extreme as it may seem, BoatU.S. recommends never swimming within 100- feet of a boathouse or dock that has electric power unless it has been shut down. In addition you should: Have a licensed electrician check your boathouse wiring to be sure it meets the requirements in National Fire Protection Association Standards for Marinas (NFPA 303) and National Electric Code requirements for Marinas (NEC 555). Because docks are exposed to the elements, their electrical systems should be inspected at least once a year.
Be sure you have Ground Fault Circuit Interrupters (GFCI) on circuits to your boat house. They are required by code in kitchens and bathrooms but not private docks or boathouses. Exercise them as recommended by the manufacture to be sure they are working properly. Work with your neighbors to be sure they are aware of the potential problems and ensure everyone’s safety. Remember, if you have neighbors who have docks within 100 feet of where you swim—they too can pose a danger. If you are in the water and feel a tingling, the natural instinct is to swim to the dock so that you can climb out but this is exactly the wrong thing to do. Swim away from the dock and shout for help but tell everyone not to enter the water. If you are present when someone is calling for help, don’t jump in the water to help. Throw a lifesaver or rowout to the person.
The Tennessee House and State Senate havepassed an act, The Noah Dean and Nate Act, which would requi re mar in a owners to install GFCIs on outlets in boat slips at marinas. It is named for two boys, ages 10 and 11, who drowned while swimming together around a marina on Lake Cherokee in Tennessee on July 4, 2012. The requirement for GFCIs for private docks of single-family homes does not exist in Georgia, but the same dangers exist.