As we enter the warm summer months, with Memorial Day just around the corner, lake and river watersport seasons are about to begin. It is important to know about the dangers of electric shock drowning (ESD).

ESD happens when a swimmer comes into contact with electrical current. The current–in this case, alternating current (AC)–causes skeletal muscular paralysis lasting for only an instant, but long enough to incapacitate a swimmer, allowing them to drown.

The electric current “leaks” from boats and docks into the water. It can come from frayed wires, improperly wired systems, or an AC grounding system that is damaged or malfunctioning.

Electrical current will always attempt to return to its source in order to complete the electrical circuit. Electrical current is resourceful and will find any way to do that, taking the path of least resistance and most conductivity. It takes only a small amount of AC to disrupt the electrical impulses that control human muscles and nerves, which can incapacitate or electrocute a person. As small an amount as 15 milliamps can cause paralysis; 100 milliamps–or a third of the amount of electricity needed to light a 40-watt light bulb–can kill a person in seconds. In comparison, a double AA battery produces 2400 milliamps per hour.

The NFPA has set aside some best practices to help reduce the risk of ESD:

  • Never swim within 100 yards of any fresh water marina or boatyard.
  • If you have a boat, have it tested to make sure it is not leaking electricity. You can buy a clamp meter and test it yourself.
  • Have a qualified electrician do any electrical work needed on a dock or on your boat.
  • Do not use a household extension cord for powering your docked boat.

According to, if you feel “tingly” in the water, you could be at risk for shock. In that case you should:

  • Have someone turn off the shore power connection at the meter base and/or unplug shore power cords.
  • Tell anyone in the water to move away from the dock.
  • Stop anyone else from entering the water.
  • If you believe someone has been shocked, reach, throw, row, but don’t go into the water to get anyone who you think has been shocked.
  • Call for help. Use 911 or VHF Channel 16.
  • Try CPR on the person; don’t stop until trained help arrives.