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Nothing says summer like a panorama of power boats docked along a marina’s pier. And while summer’s heat is enough to tempt anyone to dive into the cool water, swimming in and around a marina can endanger lives. Although many marinas and boats are well cared for, some are poorly maintained, with corroded electrical infrastructure including ground-fault circuit interrupter (GFCI) outlets that no longer function, faulty or frayed wiring and even duct-taped electrical repairs. These hazards are catalysts of electric-shock drowning (ESD) — a deadly situation that can be caused by low-level “leakage current” that escapes into the water.
Leakage currents can exist everywhere in marinas, stemming from boats, compromised dock wiring, electrical boxes and more. Swimmers in fresh water, especially, can fall victim to ESD because the human body is a better conductor of electricity than the surrounding water. Depending on the amount of electrical current in the water, a swimmer may experience a slight tingle, complete loss of muscle control or worse. When ESD occurs, a person’s muscles contract such that they cannot swim, with the possibility of drowning imminent.
One landmark incident helped draw attention to ESD prevention. While swimming at a West Virginia marina in May 2010, 15-year-old Michael Cunningham grabbed an energized ladder on a houseboat plugged into a pier circuit. He was electrocuted and killed instantly. It was later determined that the houseboat’s leakage current caused the incident. Three years after Michael’s death, West Virginia passed H. B. 3020, or the “Cunningham Act,” mandating that marinas be brought up to the latest code and all wiring be installed and maintained by qualified electricians. Other states have taken the same course, naming legislation after children who unfortunately passed away due to an electrical accident while swimming at marinas.
For the sake of safety, boat manufacturers and marina operators must collaborate to develop marina safety requirements in the NEC.
Inspired by Michael’s story and others like it, my colleague, Joe Fello, and I submitted a public input for the 2011 NEC (National Electrical Code) seeking ground-fault protection for circuits feeding marinas. It was unfortunately easy to substantiate, as the number of children who die in and around marinas while swimming is well documented. After much debate, Article 555 - Marinas, Boatyards, and Commercial and Noncommercial Docking Facilities was amended to allow up to 100 milliamps (mA) on overcurrent protective devices (OCPDs) supplying marina mains and feeder breakers. These changes spurred further research by the NFPA Fire Protection Research Foundation, which found that boat manufacturing standards allow for up to 30mA of leakage current on each boat, inspiring the NEC to reduce the 100mA threshold to that level in the 2017 version of the NEC.
Work on the 2020 version of the NEC is underway and leakage current is garnering a lot of attention. Many industry pros believe the 30mA leakage threshold isn’t practical in terms of a marina’s electrical infrastructure. The challenges are providing protection to a group of boats and the additive nature of leakage currents. A group of boats with inherent leakage currents on the same feeder could create a tripping scenario that leaves an entire marina without power. For instance, a boat emitting 29mA of leakage current is within the tolerances of boat manufacturing standards, but adding one more boat with even a small amount of leakage current shuts down the power.
More importantly, it only takes 4 to 6mA to stop a healthy human heart. Equipment level protection of 30mA — the amount of leakage current allowed for one boat per manufacturing standards — is not enough.
For the sake of safety, boat manufacturers and marina operators must collaborate to develop marina safety requirements in the NEC. NEC researchers must ask the right questions to understand the unique position of marinas and boat builders. How are boats currently built? Why is 30mA considered an acceptable standard leakage current value? Do older or newer boats emit more current? After gathering and studying new data, we may discover that boat standards or maintenance should change. Or, perhaps marinas will need to install more feeder circuits to serve a lesser number of boats.
We need to understand the challenges ahead. It is clear that something has to change, and we need to chart the course.
The industry is working through a new code cycle, and I’m sure more research will follow. This will take time, perhaps over multiple NEC code cycles. So, what can we all do to increase safety and avoid ESD danger in the meantime?
Change is a team effort. We are all on the team. By working with the NEC, spreading the word and remaining vigilant in and around marinas, we can make marinas safer havens.
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