Thursday, March 17, 2016

Electrical Shock Drowning (ESD)

May 28, 2011 Lake City, MN. A 50 year old man was electrocuted in Lake Pepin near a boat lift which had exposed wiring.
His dog was in the water, was shocked, and began to sink. Another man jumped in to rescue the dog but was shocked.  (The man did escape the water). The 50 year old man then jumped in for his dog, and the man appeared to have been electrocuted.
With spring coming quicker than the winter weather would lead you to believe, it’s time to start thinking about water safety. I am specifically talking about electrical systems on docks, piers and marinas, splash pads, public pools and let’s not forget fountains and other water features around town.
Not all cities have marinas or lakes with docks, but those that do need to really think about how those city features are used and maintained. These precautions can be related to pools, and water features around the city, which both adults and children are using for recreation as well. Just because someone isn’t swimming doesn’t mean they can’t wade, reach, or stand.
Electrical Shock Drowning (ESD) occurs in fresh water where minute amounts of AC current are present. As little as a few milliamps can incapacitate a person so they can’t move their muscles. This can occur with as little as 6mA to 16 milliamp (mA) of current. Most victims talk about a tingling in the water as they were swimming. Tingling can be felt with 1mA of current in the water. 6 milliamps will cause agonizing pain which is less than a third of the electricity used to light a 40 watt light bulb. 100 mA passing directly through the heart is almost always fatal. A voltage gradient of 2 volts per foot in fresh water is enough to kill a person who bridges it.    
Electric shock drowning can occur anywhere electricity is used near water, but is primarily most prevalent at marinas where boats are docked and plugged-in to shore power. Most cases of ESD occur in fresh water. Salt water has less resistance to electricity and the electrical gradient or difference in potential is very low. Fresh water has a higher resistance to electricity and therefore a higher electrical gradient or difference in potential. It is the difference in potential that makes it more dangerous. The electricity can cause a swimmers muscles to contract. They become immobile, can no longer move or swim, and drown.
All electrical circuits in and around water features need to be Ground Fault Circuit Interrupter (GFCI) protected. The wiring and outlets should all be regularly inspected by a licensed electrician who is familiar with the electrical codes as they pertain to marinas and water features. All GFCI, regardless of location, should be tested at least monthly to ensure they are functioning. How about a pool or water feature which has electricity for lighting, electrical outlets, etc.? Those too need to be inspected and part of a preventative maintenance program. I have been at pools where there were swim meets and the teams brought their own timing equipment, extension cords, etc. The timers were plugged into outlets on the light poles around the perimeter of the pool. None of the outlets were GFCI protected, and none of the extension cords were GFCI protected. These could cause an electrical shock issue due to improperly wired equipment, damaged cords coupled with the wet pool deck, high traffic, etc. Given the hazards it is a good idea to regularly inspect all of the docks, boat lifts, marina wiring, pools, fountains, and water features that have electrical features to ensure the people visiting those facilities are protected. In the case of marinas and docks with power to them it is recommended they be posted with no swimming. The boats hooked to the power at the marinas could contribute to the problems as they might have faulty wiring and it is best not to take the chance in that situation.

On a side note: When was the last time you tested your GFCI outlets in and around city buildings? They should be tested monthly to ensure they are functioning.

By: Paul Gladen