NFPA Journal - Summer 2022 - 61

or marina, that contains enough AC
current to disable them and result in
drowning. In recent years, a steady
stream of news stories from around the
country involving ESD deaths has
underscored the need to regard this
hazard as a serious concern around
boats, docking facilities, and marinas.
ESD does not result from contact
with electrical equipment or electrical
conductors-rather, it's a phenomenon
that can occur where boats in water
are connected to shore power electricity,
with the boats emitting a low-level
AC current that travels through the
water. If a person enters that water, the
AC current can impact the body with
sufficient force to cause skeletal and/
or muscular paralysis, rendering the
victim helpless and putting them at
risk of drowning. Higher levels of AC
current in the water can also result in
electrocution. ESD tends to occur more
frequently in freshwater environments
such as lakes and ponds than in salt
water. ESD deaths are difficult to track
and may often go unreported, and postmortem
examinations may not reveal
signs that electricity was involved in
the fatality. Even so, experts estimate
that scores of ESD deaths occur nationwide
every year.
ESD isn't specifically addressed in
, National Electrical Code®
), but it continues to have a
NFPA 70®
(NEC®
significant impact on recent changes
to the code. A number of NEC requirements
address the ESD hazard,
including some important changes
made to the 2020 edition. One of those
addressed both ground-fault protection
of equipment (GFPE) and ground-fault
circuit interrupter (GFCI) protection
in Article 555, Marinas, Boatyards,
Floating Buildings, and Commercial
and Noncommercial Docking Facilities.
With cumulative effects of leakage
current causing excess tripping of 30
milliampere GFPE devices, changes
were made to code language that
increased GFPE current settings not to
exceed 100 milliamperes on feeders and
branch circuits. This change helped
facilitate more dependable power
for marinas and docking facilities.
However, individual branch circuits
feeding single shore powered receptacles
must 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.
New 2020 NEC language also
required 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.
Additionally, Section 555.9 was
added to the code. This called for boat
hoist outlets not exceeding 240 volts
around marinas, boatyards, and docking
facilities gives notice of electrical
shock hazard risks to persons within
those areas. The code making panel
felt that signs should say more than
" No Swimming, " however, since some
people may not take that warning seriously
and swim anyway. Signs should
now say: " WARNING-POTENTIAL
SHOCK HAZARD-ELECTRICAL
CURRENTS MAY BE PRESENT IN THE
WATER. " To further aid in preventing
ESD, docking facilities were added
in the 2020 NEC, joining marinas and
boatyards as potential ESD hazard
areas covered in section 555.10.
Although still in the development
One proposal would
require emergency
electrical disconnects
within sight of the
marina power outlets,
which would allow
bystanders to quickly
de-energize power to a
docked boat and safely
release a person who
may be suffering an
electric shock.
that are installed at dwelling unit
docking facilities to have GFCI protection
for personnel. This requirement
was intended for marine areas that
include residences with private docks,
locations where ESD hazards may be
overlooked. These homes don't always
have shore power, but they may have
electrically powered boat hoists that
can introduce low-level AC current into
the water.
Language was also added to
the 2020 NEC addressing signage.
Installing permanent safety signs
stage, number of ESD-related changes
have been suggested for the 2023 NEC.
One proposal would require emergency
electrical disconnects within sight of
the marina power outlets, which would
allow bystanders to quickly de-energize
power to a docked boat and safely
release a person who may be suffering
an electric shock. Additionally,
a proposed requirement would add
equipotential planes and bonding of
equipotential planes that could help
mitigate step and touch voltages for
electrical equipment that supply power
to the equipment. There has also been
a proposal that would require modified,
repaired, or replaced equipment
to be updated to current provisions
due to exposure to harsh marine
environments.
Marinas, boatyards, and docking
facilities will always be challenging,
dynamic environments, in part because
vessels in various degrees of electrical
repair are constantly moving through
these areas. That's also why waterborne
AC current will remain a hazard
in those environments. Recent changes
to the NEC have made marinas, boatyards,
and docking facilities safer by
regulating electrical requirements,
and future editions promise to further
address ESD hazards.
For more information on the ESD
hazard, visit nfpa.org/esd.
Dean Austin is senior electrical content specialist at
NFPA. NFPA members and AHJs can use the
Technical Questions tab to post queries on NFPA 70 at
nfpa.org/70. To follow the progress on the upcoming
edition of the code, visit nfpa.org/70next.
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NFPA Journal - Summer 2022

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