NEC Code Application 555

NEC Article 555 and all of its subsets have to do with Marinas, Boatyards, Floating Buildings, and Commercial and Noncommercial Docking Facilities. In more depth, this Article has to do with “the installation of wiring and equipment in the areas comprising fixed or floating piers, wharves, docks, floating buildings, and other areas in marinas, boatyards, boat basins, boathouses, yacht clubs, boat condominiums, docking facilities,” and so on relating to electrical protection in/around a boating area. There are two different subsets in NEC Article 555 that have relation to GFCI and ELCI/GFPE (Equipment Leakage Circuit Interrupter/Ground Fault Protection Equipment) protection, and they are as follows:


NEC 555.35

This subsection is for aquatic vessels and the shore power that supplies them (not including floating buildings). It stipulates the Ground-Fault Protection of Equipment (aka a GFPE/ELCI) and Ground-Fault Circuit Interrupter (GFCI) electrical protection products for marine areas in accordance with its 4 different sections, which are:

A.) The first part of this section involves the Feeder circuits of shore power equipment. A GFPE, rated up to (but not exceeding) 100 mA, shall be provided for feeders installed on docking facilities.

B.) the second part of the section deals with the branch circuits and their circuit protection in the defined areas of this Article, which are:

1.) The first part is regarding receptacles providing shore power. These receptacles must be GFPE, and cannot be rated above 30 mA, and are required to be provided for receptacles installed in accordance with 555.33(A) (12in. above the deck surface of the pier).

2.) The second is for “outlets for other than shore power.” This means outlets supplied by branch circuits up to 150 volts to ground and 60 Amps, single phase, & up to 150 volts to ground, up to 100 Amps, three phase, shall be provided with GFCI protection for personnel.

C.) The third part of this subset section is regarding boat hoists. It states that GFCI protection for personnel shall be provided for outlets up to 240 volts that supply a boat hoist installed at docking facilities. GFCI protected receptacles not involved with shore power may also be permitted to supply boat hoists.

D.) The fourth part of this section is pertaining to leakage current measurement devices. If there are four or more receptacles supplying shore power to boats, a Listed leakage current measurement device for use in marina applications needs to be available and used to determine leakage current from each boat that will plug into the specified shore power. It also states that the listing requirement for the leakage current measurement device for use in marina applications will become effective on January 1, 2026.

NEC 555.53

This other subset pertains solely to Ground-Fault Protection for floating buildings (as part of “Part III” of this Article titled “Floating Buildings”). It states that the main overcurrent protective device that feeds into a floating building needs to have ground-fault protection below 100mA. It also states that Ground-fault (GFCI) protection of each individual branch or feeder circuit can be a sufficient alternative. This article has a lot of different rules and guidelines from most of the other NEC Articles due to the nature of the areas it is describing (outdoor aquatic areas) and for good measure. It is imperative to follow electrical safety standards to protect yourself and others from electrical shock, but it is even more dire of a need in aquatic environments because electric shock can lead to death from drowning (coined ESD, for electric shock death). This is a very serious matter that has affected a lot of families around the country, and while all NEC guidelines should be followed, this is one of the most important in terms of life and death safety for people encountering electrical appliances.

What does this code mean?

The main takeaway from this NEC Article is that electrical leakage is a serious matter around water, as it can result in serious injury or even ESD. While feeder circuits (the power source for the entire marina) need a large level (up to 100 mA) of GFPE protection, it is best practice to have GFPE at each and every dock slip where a boat can plug in to shore power, to both better protect everyone in a marina and to have a more accurate diagnosis of the source of electrical leakage. A good example of this would be two separate boats leaking 40mA to ground. These boats would not trip the feeder circuit (as the total leakage is at 80mA) but could cause serious harm to anyone in the water, so having a 30mA GFPE at each shore power location could preemptively solve this problem (both in terms of safety for everyone and identifying the source of the problem quickly and effectively).

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