Electric shock: a hidden danger in everyday shipboard work

An electric shock poses a significant risk on ships, with potential consequences ranging from burns and injuries to death. Factors influencing the outcome include voltage, current, the path of the current through the body, and the duration of exposure. Even a small current over 10 milliamperes can cause involuntary muscle contractions, while higher levels may lead to severe pain, respiratory arrest, and possible fatality. The heart's rhythmic pumping ceases around 1 amp.

Electrical systems on ships operate at varying voltages, from low-voltage signal equipment to switchboards exceeding 1,000 volts. Care should be exercised when voltage surpasses 50 volts. The severity of the danger depends on multiple circumstances, such as equipment condition, the electrical system, and the work environment. Moisture, sweat, and humidity on the body increase conductivity, thereby raising the risk for those onboard.

Onboard ships, there are several electrical distribution systems, with voltages ranging from 5 volts for signal power to over 1000 volts in switchboards. The voltage typically decreases to 440 volts for machinery and 220 volts for lighting and sockets used for portable equipment. The Liberia Maritime Authority recently produced a Marine Advisory to prevent electrocution casualties, emphasizing portable electrical equipment.

A review of cases aligns well with the LMA Advisory. For instance, a crew member died while using a portable lamp for cargo operations due to incorrect wiring, resulting in the light housing becoming energized. Another case involved a senior crew member who died while repairing fixed lighting without first isolating the electrical supply. Risk points onboard ships include improperly wired metal objects, which can become the path of least resistance for electricity to reach the ground.

Various tools used onboard, such as electric grinders, angle grinders, and welding machines, also present electrocution hazards. In one case, a crew member died from electrocution while using a grinder for routine maintenance due to an electrical fault in the tool. Another fatal accident occurred when a crew member on the main deck was found unconscious after repairing railings, with the welding machine responsible for the electrocution due to an older AC power system operating above the recommended voltage and intermittent rain showers.