The odyssey for ground-fault protection (GFP) of marine equipment began with the addition of Sec. 555.3 in the 2011 NEC. This section called for “ground-fault protection” on the main overcurrent protective device (OCPD) servicing a marina or boatyard. This “ground-fault protection” was to have a maximum 100mA capacity. In lieu of this “ground-fault protection” on the main, individual ground-fault circuit interrupter (GFCI) protection on each branch circuit or feeder was permitted. But confusion existed with this provision before the ink dried on the paper, as this new requirement was aimed at “protection for personnel” not ground-fault protection (GFP) for equipment. Yet the title and the Code language referenced “ground-fault protection.”
This GFP requirement was initially proposed because of numerous fatalities occurring in and around marinas due to human contact with stray currents in contact with the water (Photo 1). Part of the substantiation noted several deaths due to drowning where the victims lost function of their limbs and the ability to react or swim — now commonly known as electric shock drowning (ESD). Although this 2011 NEC requirement almost certainly provided some degree of protection, there were still issues that needed to be addressed if the concern was with protection of personnel.
For the 2017 NEC, this maximum 100mA capacity was reduced to 30mA. This 30mA ground-fault limit was consistent with that recommended in a report titled, “Assessment of Hazardous Voltage/Current in Marinas, Boatyards and Floating Buildings,” which was commissioned by NFPA’s Fire Protection Research Foundation and conducted by the American Boat and Yacht Council (ABYC) Foundation, Inc. This report stated in part:
“ABYC Standards recommend a device that interrupts the source of power feeding a fault within 100 msec from the moment stray current exceeds 30mA. While 30mA through the body is more than enough to kill a swimmer (above the ‘let-go’ threshold established for a Class A GFCI device), it is not sufficient to assume that all the 30mA leaking into the water will actually go through the swimmer. Rather, U. S. Coast Guard studies have shown that due to hemispherical ‘spreading’ of the electric field, only a portion of the leakage current will go thru the swimmer. The main exception to this occurs when the swimmer comes into direct contact with the voltage source itself, for example by grabbing a metallic ladder that has become energized. 30mA represents an acceptable level that ABYC expects to prevent most electric shock drowning (ESD) incidents while remaining practical enough to minimize unnecessary tripping.” The substantiation for this reduction to 30mA went on to state, “It should also be noted that ABYC standards, since Dec. 31, 2012, have required 30mA equipment leakage circuit interrupters (ELCI) on watercraft. While boats are not subject to NEC requirements, boats are connected to electrical branch circuits that are.”
Once this 30mA maximum GFP requirement went into practical application, the part about “remaining practical enough to minimize unnecessary tripping” proved to be unreliable. Through a cumulative effect, it did not take but a few boats leaking current into the water around a marina before the 30mA level was exceeded. This 30mA maximum required GFP requirement virtually shut down new construction of marinas and boatyards in jurisdictions enforcing the 2017 NEC. The marina industry desperately needed some relief from this 30mA maximum GFP requirement.
The GFP requirements of marinas, boatyards, and docking facilities were extensively revised in the 2020 NEC. These GFP requirements (previously located in Sec. 555.3 and now found in Sec. 555.35) were divided into three parts to provide clarity for these important ground-fault requirements (Photo 2).
• Section 555.35(A)(1) addresses shore power receptacles with individual GFPE not to exceed 30mA.
• Section 555.35(A)(2) addresses 15A and 20A receptacles for other than shore power with Class A GFCI protection (4mA to 6mA) being provided in accordance with Sec. 210.8 through a reference to Sec. 555.33(B)(1).
• Section 555.35(A)(3) addresses 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 100mA with coordination with downstream GFPE permitted at the feeder overcurrent protective device.
An exception was added that would exempt transformer secondary conductors of a separately derived system [not to 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% of ESD incidents could be avoided by the 30mA protection at the shore power receptacles, whereas the existing overall 30mA 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. As pointed out in Sec. 90.2, the NEC does not have jurisdiction over the vessels at marinas. While its rules cannot demand that the vessels be tested for current leakage, language was put in place in Sec. 555.35(B) to require leakage current measurement devices at marinas and boatyards where more than three receptacles supply shore power to boats.
These revisions to GPE and GFCI provisions at marinas should provide the needed relief the marina industry has been desperately seeking. It should also be noted that a Tentative Interim Amendment (TIA 17-15) was issued by the NFPA Standards Council on April 10, 2018, with an effective date of April 30, 2018. This TIA was for Sec. 555.2 and Sec. 555.3 of the 2017 NEC. A Tentative Interim Amendment (TIA) is tentative because it has not been processed through the entire Code-making process. It is interim because it is effective only between editions of the Code. A TIA automatically becomes a public input of the proponent for the next edition of the Code; as such, it then is subject to all the procedures of the Code-making process.
Part of the substantiation for this TIA stated that “the language of Sec. 555.3 is revised (by the TIA) to clarify that protection be provided for the branch circuit and feeder conductors. The revised language relieves the concern that ground-fault protection could be enforced on a main breaker at the service or in a panelboard where all feeders and branch circuits are already protected at 30mA. The language permits levels of ground fault less than 30mA and also permits time delay where 30mA is provided on a branch circuit and a feeder to support coordination of the circuits.”
Lofland is the director of education, codes and standards for IAEI, Richardson, Texas. He represents IAEI as chairman of NFPA’s Code Making Panel (CMP) 7 for the National Electrical Code (NEC), serves on NFPA’s Electrical Section Executive Committee, and is a member of UL’s Electrical Council. He is also the principal author of several IAEI publications, including IAEI’s NEC Analysis of Changes. Prior to his position with the International Office of IAEI, Lofland spent 16 years with the City of Garland (Texas) serving as their chief electrical inspector. He holds a Master Electrician license from the State of Texas. He can be reached at [email protected].
Inspector Intel articles are provided by the International Association of Electrical Inspectors (IAEI), www.iaei.org, a membership-driven, non-profit association headquartered in Richardson, Texas, that promotes electrical safety throughout the industry by providing education, certification of inspectors, advocacy, partnerships, and expert leadership in electrical codes and standards.
