Walk the docks of any marina worldwide and you’ll see dozens of brightly colored power cables connecting moored vessels with onshore electrical feeds. But the tranquil scene may not be as safe as it appears, particularly for anyone who winds up in the water.
Recent years have brought growing awareness of Electric Shock Drowning (ESD), a condition created by electricity accidentally “leaking” into the water as a result of a faulty shore power connection. According to the Electric Shock Drowning Prevention Association, an electric leak of just 10 to 15 milliamps — or around 1/50 the wattage required to power a standard 60-watt light bulb — can fatally incapacitate a person in the water. ESD is a serious problem that results in multiple deaths every year.
The cause of this escaped electrical current can frequently be traced to equipment aboard the vessel, resulting from long-term corrosion, improper installation, or faulty ground circuits. In most cases, these leaks and resulting accidents can be prevented.
The safest way to protect against stray electrical currents is to install a shore power converter with built-in isolation transformer on board the vessel. In simple terms, the device converts potentially unreliable AC shore power into clean supply for onboard distribution, effectively creating an onboard isolated power source, which is critically important. Because electrical current always tries to return to its source, this arrangement ensures that any leaking current will simply return to the converter instead of attempting to return to shore through the water.
Beyond that, the shore power converter corrects against the potential for polarity faults arising from an unreliable shore power supply. Reversed polarity can be extremely dangerous on board a yacht because it allows current to continue flowing through AC-powered appliances even when they’re off. When polarity is reversed on common household appliances like refrigerators, their metal casing can become energized with stray electrical current, creating a potential electrocution hazard.
The safest way to protect against stray electrical currents is to install a shore power converter with built-in isolation transformer on board the vessel.
The shore power converter can accept a wide range of commonly accepted voltages and frequencies in marinas worldwide to provide the vessel the same dedicated steady voltage and frequency. This opens up the number of docks the vessel can dock without having to worry about voltage and frequency.
While adding a shore power converter to protect against shore power woes does represent an additional cost, the device can pay for itself by protecting against the galvanic corrosion that can occur between boats in a marina that share a common AC shore power ground. By preventing this corrosive damage to underwater fittings, the converter can reduce overall maintenance expenses. Aboard the vessel, it further protects against potential damage to sensitive equipment that can result from power surges and current irregularities.
Most importantly, a shore power converter can save lives by protecting against ESD — reason enough to require one on every yacht.
This article originally ran in the October 2021 issue of Dockwalk.