Electric shock drowning has become the catchall term that includes in-water electrocution — what happened to Lucas — and drowning that is a result of becoming paralyzed by electricity in the water. There have been more than 100 confirmed cases of ESD, including four over last summer’s July 4th holiday. Due to the difficulty of detection, many drownings caused by ESD are not properly reported or investigated. An autopsy won’t reveal evidence of ESD, so investigators have to rely on eyewitnesses hearing cries for help or accounts of others in the water feeling a tingling sensation. Otherwise, it will be reported as a drowning. Meanwhile the real cause of death — the electricity in the water — goes undetected.
While most ESD fatalities happen around boats at marinas, there have also been cases in water fountains, irrigation ditches, golf course ponds and other bodies of water dating back to the mid ’80s. It’s not uncommon for would-be rescuers to jump in to help and become victims themselves. There have even been cases in which people jumped in to help their dog, which survived and the people perished.
Numerous factors come into play. The amount of electricity in the water; freshwater purity; the size, gender and orientation of the person in the water; the distance from the power source, etc. will influence whether a person is electrocuted, paralyzed or just feels a tingle. Regardless of the outcome, when it comes to a boat plugged into shore power, there are two problems that must be present for electricity to get into the water.
The first is an electrical fault on the boat — a short circuit, a wiring error, a malfunctioning appliance — something that is sending AC electricity away from its intended path. Electricity travels in a circular loop from its source to the load — say, a light bulb — and then back to its source. Hence the term circuit. If a fault disrupts this loop, the electricity seeks another path back to its source.
A proper AC electrical system is designed to handle faults using the green “grounding” wire, which is a backup return path that completes the circuit to safely route the electricity back to the power source on shore. In doing so, a fault or short typically trips a circuit breaker to remove danger. But what happens if this backup path itself is somehow compromised — or even missing? One of these situations is the second necessary element for ESD to occur. Now we have a recipe for disaster because the only path left for electricity is through the water.
The result is a potentially dangerous patch of water that radiates out from the boat’s underwater metals such as the propellers, sterndrive or through-hull fittings. Anyone in this patch of water is in danger of ESD.
ESD remains a freshwater phenomenon. Fresh water is highly resistant to electrical flow, so a person swimming in fresh water becomes the path of least resistance. Seawater’s salt content makes it more than 500 times more conductive than fresh water. This, along with a person’s natural skin/fat resistance, causes almost all the electricity to flow around a swimmer in seawater. Fresh water focuses almost all the electrical flow through the person — and it doesn’t take much electrical flow to kill.
Electrical flow is measured in amps. It takes only one-third (0.33) of an amp to power a 40-watt light bulb. Now consider that a Taser gun can incapacitate a person using only 2 milliamps (mA) — that’s 0.002 amps. It takes only 10 to 22 mA (0.01 to 0.022 amps) to cause paralysis and loss of ability to breathe. At 50 to 65 mA (0.05 to 0.065 amps) fatal heart fibrillation becomes possible, and anything more than 100 mA (0.1 amp) — less than a third of the electricity required to power a 40-watt light bulb — is considered absolutely deadly.