A version of this blog was originally published in 2022. It has been updated to reflect the most recent information.
You would think that as someone who lives and previously conducted electrical inspections in Michigan, a state with 3,288 miles of freshwater shoreline and countless marinas, I would have known about electric shock drowning (ESD) before joining NFPA®. Well, you would be wrong; I had no idea what ESD was until I started working at NFPA.
At a recent electrical inspectors’ conference, I began to wonder if I was the only inspector who had been in the dark about ESD. I asked if anyone knew what ESD was, and very few did. This was surprising to me, but also provided me with an opportunity to educate them. So, how can an electrical inspector have an impact? We must first answer the question, “What is ESD?”
According to the Electric Shock Drowning Prevention Association, ESD occurs when a typically low-level alternating current (AC) passes through the body with sufficient force to cause skeletal muscular paralysis, rendering a swimmer in freshwater unable to keep him or herself afloat, eventually resulting in the drowning of the victim. Higher levels of AC in the water could also result in death via electrocution. It has been said that ESD is the catch-all phrase that encompasses all in-water shock casualties and fatalities. ESD occurs more in freshwater environments than in saltwater, which is why ESD is of particular concern around freshwater docking facilities, marinas, lakes, and ponds.
Creating a specific code section in NFPA 70®, National Electrical Code® (NEC®), for ESD may sound simple, but it is not. ESD is not a piece of electrical equipment or an electrical conductor but rather a phenomenon that can occur in areas where boats are connected to shore power electricity. Increased knowledge on the risk of ESD has impacted the construction of boats, marinas, and docking facilities, which may help reduce occurrences of ESD. And even though ESD isn’t specifically addressed in the NEC, it has had a significant impact on recent changes that have been made in it.
New solutions for helping eliminate ESD have become a regular subject in the code-making process, public inputs, and comments for potential new NEC requirements. Changes to the 2023 NEC that electrical inspectors should be aware of and that could lead to a reduction in electric shock drowning deaths include the following:
- Requiring emergency shutoff devices or emergency disconnects located within sight of the marina power outlets or other enclosures providing power to boats. They are to be marked “Emergency Shutoff,” readily accessible, and externally operable, which allows bystanders to quickly de-energize power to the boat and safely release a person who may be suffering an electric shock.
- Adding equipotential planes and bonding of equipotential planes that could help mitigate step and touch voltages for electrical equipment that supply power to the equipment.
- Requiring that modified, repaired, or replaced electrical enclosures, devices, or wiring methods comply with the current provisions of the NEC. The installation also requires the circuit be inspected due to exposure to harsh environments.
- Requiring all luminaires and retrofit kits to be listed and identified for use in their intended environment. Also requiring that luminaires installed below the highest tide level or electrical datum plane and likely to be periodically submersed comply with 555.38(B).
As conversations around ESD continue throughout the code development process, it is important to remember which edition of the NEC is being enforced in your area, and how you as an electrical inspector can use those sections to make an impact in reducing ESD. Through enforcement of electrical codes, the inspector can help educate owners and installers about ESD risks. Here are just a few topics inspectors might want to look up in the NEC:
- Signage – You might be wondering, “How can signs help prevent ESD?” They can do it by continuing to warn everybody of the true dangers facing them. These areas are challenged with constantly changing environments because numerous boats in various degrees of electrical repair travel in and out of these facilities all the time. This can make a place you may otherwise consider swimming in potentially unsafe due to the presence of low-level AC (leakage current). Installing permanent safety signs around marinas, boatyards, and docking facilities gives notice of the ESD risk to persons within those areas. Signs should say more than “No Swimming” since some people may not take that warning seriously and swim anyway. Code language was added to have signs state: “No Swimming / Warning / Potential Shock Hazard / Electrical Currents May Be Present in the Water.” To aid in further preventing ESD, docking facilities were added to the list of marinas and boatyards found in 555.10 of the 2020 NEC.
- Ground-fault protection – Article 555, Marinas, Boatyards, Floating Buildings, and Commercial and Noncommercial Docking Facilities,addresses both ground-fault protection of equipment (GFPE) and ground-fault circuit interrupter (GFCI) protection. With cumulative effects of leakage current causing excess tripping of 30 milliampere GFPE devices, changes were made to the code language for the 2023 edition of the NEC that increased GFPE current settings not to exceed 100 milliamperes on feeders and 30 milliamperes on branch circuits, which will require inspectors to verify devices are properly located in the electrical system. This change helps facilitate more dependable power for marinas and docking facilities. Branch circuits feeding single shore power receptacles must still have individual GFPE devices set to open at currents not exceeding 30 milliamperes. Coincidentally, this requirement matches main breaker settings in boats manufactured after July 31, 2017. Outlets for non–shore power had the GFCI protection for personnel expanded in the 2023 NEC to cover 150 volts to ground and 60 amperes, single phase, and 150 volts or less to ground and 100 amperes or less, three phase.
- Leakage current measurement device – The 2020 NEC language allowed electrical inspectors to require marinas, boatyards, and docking facilities that have more than three receptacles supplying shore power to boats to have a leakage current measurement device available on site. This device would allow facility operators to isolate and notify boat owners of leakage current so repairs could be made by a qualified person, thus helping to eliminate a potential ESD risk. The new language in the 2023 NEC requires the device to be listed for use in marina applications. This requirement doesn’t become effective until January 1, 2026.
- Private docks – Locations where ESD hazards may easily get overlooked or not inspected are on lakes surrounded by homes with private docks. These homes don’t always have shore power but may have electrically powered boat hoists. Section 555.35(C) requires boat hoist outlets not exceeding 240 volts installed at dwelling unit docking facilities to have GFCI protection for personnel.
We have seen notable code changes within Article 555 over the last several cycles. Prior to the 2017 NEC, warning signs around marinas, boatyards, or docking facilities were not an NEC requirement, but they are now. GFCI and GFPE have had changes made within Article 555 over the 2017, 2020, and 2023 NEC cycles. There’s been a lot of positive influence on the codes because of the risks surrounding ESD, including regulating electrical requirements in marinas, boatyards, and docking facilities, rendering them much safer now. But you still can’t swim there!
As inspectors, we can help raise awareness of ESD in our communities. It starts with educating ourselves. Visit this webpage to learn more about this topic and ways to help mitigate the risk of ESD.
Important Notice: Any opinion expressed in this column (blog, article) is the opinion of the author and does not necessarily represent the official position of NFPA or its Technical Committees. In addition, this piece is neither intended, nor should it be relied upon, to provide professional consultation or services.
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