Marinas, Boatyards, and Docking Facilities

Article 555 is dominated by electric shock drowning, ESD, where current leaking from a boat or a dock into fresh water passes through a swimmer and stops their muscles. The Code responds with ground-fault protection set to trip at low leakage levels for the feeders and receptacles serving docks, plus thorough bonding of all the metal that makes up the pier.

I test the leakage on these systems and take a nuisance trip as information, not an annoyance, because it may be telling me a boat on the dock is bleeding current into the water. Between the corrosive environment and the swimmers, a marina is one of the few places where a milliamp genuinely decides whether someone lives.

When it applies

This governs power to docks, piers and boats. It is written around a deadly hazard: electric shock drowning, where stray current in the water paralyzes a swimmer. The article calls for leakage-current protection on the supply and thorough bonding of the metal parts of the wet structure so voltage cannot build up in the water.

Common mistakes

• Skipping the ground-fault or leakage protection that trips before a dangerous current reaches the water.
• Leaving dock metalwork unbonded so a fault energizes the structure and the water around it.
• Using standard indoor-grade equipment where the salt, spray and constant damp demand corrosion-rated gear.

In the field

Around water I treat leakage-current protection as non-negotiable and I test it. Electric shock drowning gives no warning and leaves no mark, so a swimmer never knows the water is charged until it is too late — the protection has to catch the fault they cannot feel coming.