Electrical Shocks Around Boats: Dock Safety Hazards Explained

Electric shocks around boats and docks can be extremely dangerous and even fatal. Electric Shock Drowning (ESD) occurs when an AC electrical current passes through the body of someone in the water, causing muscle paralysis and ultimately drowning. This phenomenon is more common in freshwater than saltwater, as the human body is a better conductor of electricity than saltwater. Faulty wiring, equipment, and appliances on boats and docks are often the cause of these electrical currents. To prevent ESD, it is crucial to never swim near docks or boats with AC power and to ensure that electrical systems are regularly inspected and maintained by qualified professionals.

Faulty wiring and equipment on boats or docks

Electric shock drowning (ESD) is a serious and often fatal issue that can be caused by faulty wiring and equipment on boats or docks. Faults in wiring or equipment can allow electricity to leak into the water, electrifying it and causing electric shock to anyone who enters. This is a particular issue in freshwater, where the human body is a better conductor of electricity than the water itself. Saltwater, on the other hand, allows the currents to pass around humans.

Faulty wiring can be caused by a boat owner attempting to repair or upgrade a vessel's electrical systems without the proper knowledge. It is important to note that there are differences between household wiring and boat wiring, and if you are not 100% certain of what you are doing with shore-power repairs, it is recommended that you hire a professional.

The dangers of electric shock drowning are heightened by the fact that there is often no visible warning that the water is electrified. There may be no burn marks, smoke, or blown-out circuit breakers to indicate an issue. As a result, victims may not immediately feel the electrical current when they enter the water, giving them the false impression that it is safe to swim.

To prevent electric shock drowning, it is crucial to never swim near any dock or boat where AC power is in use. This includes swimming in marinas, especially off boats. If you suspect electrical currents are leaking into the water, alert the owners or consult a technician. You can also test for electrical currents in the water using an AC clamp-type meter.

To reduce the risk of electric shock drowning, individuals should never enter the water within 150 feet of any electrical equipment or wiring. This can be enforced by posting "No Swimming" signs in the area. In addition, it is recommended to have a qualified marine electrician inspect your private dock annually and install ground-fault protection on your boat and private dock.

Faults created when a boat owner attempts repairs or upgrades

Electric shock drowning (ESD) is a serious issue that can be caused by faults created when a boat owner attempts to repair or upgrade their vessel's electrical systems. While boat owners may attempt these repairs or upgrades with the best of intentions, a lack of knowledge about the differences between household wiring and boat wiring can lead to dangerous faults in the electrical system.

One common issue is corrosion, which can affect battery terminals, connections, and major leads. Corrosion can cause the copper wiring to turn into brittle fibers, reducing its ability to transmit an electrical charge effectively. This can lead to components operating intermittently or not at all. To prevent corrosion, boat owners should regularly inspect their battery terminals, connections, and leads, and use a corrosion inhibitor or replace corroded components.

Another issue that can cause electrical faults is faulty wiring. Boat owners who are not familiar with shore-power repairs can inadvertently create wiring issues that can lead to dangerous electrical currents leaking into the water. This can be especially hazardous if the boat is in freshwater, as the body is a better conductor of electricity in freshwater than in saltwater.

To avoid these issues, boat owners should be cautious when attempting repairs or upgrades to their vessel's electrical systems. If they are not 100% certain of what they are doing, it is recommended to hire a professional to ensure the work is done correctly and safely. Regular inspections by a qualified marine electrician can also help identify and address any potential electrical hazards.

By taking these precautions, boat owners can help reduce the risk of electrical faults and create a safer environment for themselves and others around their boats and docks.

Differences between household and boat wiring

Electric shock drowning (ESD) is a serious risk around boats and docks, and it is often the result of faulty wiring and equipment. This can occur when boat owners attempt repairs or upgrades without understanding the differences between household and boat wiring.

Boat wiring must be highly resistant and durable in the marine environment, with the ability to withstand salt, vibration, bilge water, engine oil, and extreme temperatures. The wires and cables on a boat include shore power cords and marine battery cables.

Marine-Grade Materials:

Boat wiring requires high-quality, marine-rated electrical components. This includes tinned conductors to minimize corrosion, multi-stranded conductors for flexibility and fracture resistance, and heavy-duty insulation that is moisture-, oil-, and heat-resistant.

Cable Sizing:

Boat wiring cables are sized based on the length of the cable and the current (amperage) flowing through it. The relationship between cable length, current flow, and cable size is essential to ensure adequate voltage and avoid performance issues or safety hazards.

Ground Cable:

In boat wiring, the ground (negative) cable is an integral part of the circuit and must be sized the same as the positive cable. Each appliance should have its own positive and negative cables, ensuring independent ground cables to avoid devastating stray currents.

Terminals:

Boat wiring uses specific terminals that match the cable size, such as red terminals for 22 to 18-gauge cables and blue terminals for 16 to 14-gauge cables. Properly sizing and installing terminals is crucial to prevent resistance and heat-related issues.

Overcurrent Protection:

Fuses and circuit breakers are essential in boat wiring to prevent electrical fires. These overcurrent protection devices must be properly sized for their circuit and placed close to the electrical source. Sizing is based on cable sizes rather than appliance amperage draw.

Wiring Practices:

Boat wiring should be installed as high as possible, avoiding bilge water and damp areas. It is important to use twisted-pair conductors near a compass and to avoid tapping into existing circuits when installing new equipment. Instead, run a new duplex cable from the distribution panel.

Colour Coding:

Colour coding in boat wiring can be different from household wiring. While black is often used for DC negative, it may also be used for the live wire in AC circuits, creating potential confusion. Yellow is recommended for DC negative to reduce this risk.

Coax Cable:

High-quality coax cable is critical for effective radio functioning. Fully-tinned, 96% braid coax cable ensures optimal performance, and proper installation of connectors and terminals is essential.

Separation of DC and AC Wiring:

DC and AC wiring should be kept separate whenever possible. If they must be bundled together, use a sheath to maintain separation and ensure safety.

Battery Isolation:

When working on the DC system, it is crucial to isolate the batteries and shut off all potential AC power sources, such as shore power, an onboard AC generator, or an inverter.

These differences between household and boat wiring highlight the specialized nature of marine electrical systems. Understanding and implementing these distinctions are vital to ensure safety, prevent electrical issues, and maintain the reliability of electrical equipment on boats.

Electric shock drowning (ESD)

ESD is a particular risk in freshwater, where the body is a better conductor of electricity than the water itself (in saltwater, the opposite is true). This means that a person immersed in freshwater is at risk of having an electric current pass through their body, causing skeletal muscular paralysis and impairing their ability to swim or stay afloat.

The causes of electrical currents leaking into the water can vary but are often the result of faulty wiring and equipment on boats or docks. This can include improperly wired pumps, lighting, or improperly grounded wires. In some cases, stray currents in the ground can also be a factor. It's important to note that many bodies of water can become brackish or fresh, even if they were previously saltwater, depending on factors such as tides, wind, and rainfall.

To prevent ESD, it is crucial to never swim near any dock or boat where AC power is in use. Individuals should maintain a safe distance of at least 150 feet from any electrical equipment or wiring before entering the water. Regular inspections by qualified marine electricians are essential, and the use of ground-fault protection devices can help mitigate the risk.

If you suspect someone has been shocked by electricity in the water, it is important to act quickly. Do not enter the water yourself, as you could become a victim too. Instead, throw a flotation device to the person and call for help immediately. Turn off the shore power connection and disconnect the power cord from the pedestal. Stay clear of the water near the marina or dock and seek medical attention if necessary.

Preventing ESD

Electric Shock Drowning (ESD) is a serious issue that can lead to severe injury and even death. It occurs when an electrical current flows through the body of an individual in the water, causing muscle paralysis and, eventually, drowning. Here are some ways to prevent ESD:

• Never swim near boats or docks: This is the most important message. To minimise risk, do not enter the water within 150 feet of electrical equipment or wiring. This includes swimming in marinas, especially off boats.
• Warning signage: Ensure warning signs are posted on all docks, including residential ones, where electricity is in use.
• Ground-fault protection: Install ground-fault protection on your boat and private dock. This can be done by installing a ground fault circuit interrupter (GFCI) at the dock pedestal, which will trip if a dangerous current escapes.
• Hire a professional: Faulty wiring and equipment on boats or docks are often the cause of electrical currents leaking into the water. If you are not 100% certain about what you are doing with shore-power repairs, it is recommended to hire a professional.
• Test for electrical currents: Use an AC clamp-type meter to test if there are dangerous electrical currents in the water around your boat. If the reading is above zero, this indicates that there is current flowing into the water, which could be dangerous and should be investigated.
• Regular inspections: Have a qualified marine electrician inspect your private dock annually and perform an annual inspection of your boat's electrical system.
• Use proper power cords: Only use power cords that are in good condition and properly rated for marine use. Do not use common household extension cords.
• Equipment leakage circuit interrupter (ELCI): Install an ELCI on your boat. This device will detect any electrical leakage and cut off power to prevent electric shock.

Remember, ESD is preventable, and by following these measures, you can help ensure the safety of individuals around boats and docks.

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