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555.35 GFPE and GFCI Protection in Marinas, Boatyards, Floating Buildings, and Commercial and Noncommercial Docking Facilities

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Change Summary

  • Ground-Fault Protection of Equipment (GFPE) and Ground-Fault Circuit-Interrupter (GFCI) Protection:
    GFP protection divided into three parts:
    555.35(A) addresses shore power receptacles (not to exceed 30 mA),
    555.35(B) addresses 15- and 20 ampere receptacles for other than shore power [GFCI protection (4 to 6 mA)], and
    555.35(C) addresses feeder and branch circuit conductors that are installed on docking facilities (not to exceed 100 mA). Language added to require leakage current measurement devices.
NEC® Text

555.35 Ground-Fault Protection of Equipment
(GFPE) and Ground-Fault Circuit Interrupter
(GFCI) Protection.
(A) Ground-Fault Protection. For other than floating buildings, ground-fault protection for docking facilities shall be provided in accordance with 555.35(A)(1) through (A)(3).
(1) Receptacles Providing Shore Power. Receptacles installed in accordance with 555.33(A) shall have individual GFPE set to open at currents not exceeding 30 milliamperes.
(2) GFCI Protection for Personnel. All 125-volt, singlephase, 15- and 20-ampere receptacles for other than shore power shall be protected in accordance with 555.33(B)(1) and (B)(2).
(3) Feeder and Branch-Circuit Conductors with GFPE. Feeder and branch-circuit conductors that are installed on docking facilities shall be provided with GFPE set to open at currents not exceeding 100 milliamperes. Coordination with downstream GFPE shall be permitted at the feeder overcurrent protective device.
Exception to (3): Transformer secondary conductors of a separately derived system that do not exceed 3 m (10 ft) and are installed in a raceway shall be permitted to be installed without ground-fault protection. This exception shall also apply to the supply terminals of the equipment supplied by the transformer secondary conductors.
(B) Leakage Current Measurement Device. Where more than three receptacles supply shore power to boats, a leakage current measurement device shall be available and be used to determine leakage current from each boat that will utilize shore power.
Informational Note No. 1: Leakage current measurement will provide the capability to determine when an individual boat has defective wiring or other problems contributing to hazardous voltage and current. The use of a test device will allow the facility operator to identify a boat that is creating problems. In some cases a single boat may cause an upstream GFPE device protecting a feeder to operate even though multiple boats are supplied from the same feeder. The use of a test device will help the facility operator prevent a particular boat from contributing to hazardous voltage and current in the marina area.
Informational Note No. 2: An annual test of each boat with the leakage current measurement device is a prudent step toward determining if a boat has defective wiring that may be contributing hazardous voltage and current. Where the leakage current measurement device reveals that a boat is contributing hazardous voltage and current, repairs should be made to the boat before it is permitted to utilize shore power.

Material taken from the National Electric Code® is reprinted with permission from NFPA 70®, 2020 edition.
National Electrical Code®, Copyright 2019, National Fire Protection Association, Quincy, MA. All rights reserved.

Expert Analysis

For the 2020 NEC, the ground-fault protection (GFP) requirements of marinas, boatyards, and docking facilities was extensively revised. These GFP requirements (previously located at 555.3) were divided into three parts to provide clarity for these important ground-fault requirements. Section 555.35(A)(1) addresses shore power receptacles with individual GFPE not to exceed 30 milliamperes (mA). Section 555.35(A) (2) addresses 15- and 20-ampere receptacles for other than shore power with Class A GFCI protection (4 to 6 mA) being provided in accordance with 210.8 through a reference to 555.33(B)(1). Section 555.35(A)(3) will address feeder and branch circuit conductors providing power to a slip and installed on docking facilities to be provided with GFPE set to open at currents not exceeding 100 mA with coordination with downstream GFPE permitted at the feeder overcurrent protective device.

555.35

An exception was added which would exempt transformer secondary conductors of a separately derived system [not exceed 3 m (10 ft] installed in a raceway from this GFPE protection as it would be difficult to provide ground-fault protection on the conductors from the transformer to the first panelboard where the transformer resides on the docking facility. It was noted in the substantiation that 50 percent of the electric shock drownings (ESD) incidents could be avoided by the 30 mA protection at the shore power receptacles whereas the existing overall 30 mA ground-fault protection for the entire marina was too low for most marinas. Informational notes were also added to address the concerns regarding vessel testing to alleviate potential leakage current that contributes to ESD as test data has shown that a great deal of the stray current in the water around marinas comes from the boats (vessels) themselves. While the NEC rules cannot demand that the vessels be tested for current leakage, language will be put in place to require leakage current measurement devices to be in place and available at marinas and boatyards where more than three receptacles supply shore power to boats.

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