Many people have experienced the pleasure of relaxing on a boat on a bright summer day. The sun shines, seagulls caw, and a sense of relaxation permeates the air. Imagine you are there right now, relaxing on your private yacht, and you see a family approach their own boat, ready to take it out for the day. It is an especially hot day, so when the kids ask if they can swim first, no one protests. You watch the kids jump into the water and swim around the boat. Very quickly, you realize something is wrong as one child appears to freeze, unable to move, and begins to sink. She is experiencing electric shock drowning (ESD) and if she isn’t pulled from the water immediately, she will drown.
ESD tragically occurs when AC current passes through a person’s body with enough force to cause muscular paralysis, incapacitating the individual immersed in water, which leads to the individual drowning. It takes as little as 10 mA of electricity to paralyze a person, leaving the person helpless in the water. While ESD can occur in any location where electricity is near water, it most often occurs in public and private marinas and docks. There are two typical sources of electrical energy in water: