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C I R C U I T P R O T E C T I O N
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Specifications subject to change. See bluesea.com for current information.
AC Ground Faults, ELCI, the Boater, and ABYC Explained
ELCI detects that current is not balanced and opens (trips)—breaking circuit
FAULTY GROUND
Marine Electrical System
20AMPS
19.970AMPS
SHORT LIMITED TO
0.030AMPS (30mA)
19.970AMPS
THROUGH
LOAD
19.970AMPS
20AMPS
CURRENT COIL
POTENTIALHAZARD
BROKEN GROUND
ENERGIZED
SURFACE
HOT
NEUTRAL
GROUND
120 VOLT 60 Hz
POTENTIALHAZARD
OPENS WHEN AN IMBALLANCE IN
CURRENT IS DETECTED
ELCI detects that current is not balanced and opens (trips)—breaking circuit
20AMPS
19.970AMPS
CURRENT LEAKING TO GROUND
0.030AMPS (30mA)
19.970AMPS
THROUGH
LOAD
19.970AMPS
20AMPS
OPENS WHEN AN IMBALLANCE IN
CURRENT IS DETECTED
GROUND FAULT
Marine Electrical System
CURRENT COIL
0.030AMPS (30mA) CURRENT LEAKING FROM HOT WIRE
HOT
NEUTRAL
GROUND
120 VOLT 60 Hz
ELCI detects that current is balanced and remains closed—completing circuit
20AMPS
20AMPS
20AMPS
THROUGH
LOAD
20AMPS
CLOSED
CURRENT COIL
PROPERLY FUNCTIONING
Marine Electrical System
HOT
NEUTRAL
GROUND
120 VOLT 60 Hz
A Coast Guard sponsored study showed numerous instances of electrical
leakage causing drowning or potential drowning even though the shock
did not directly cause electrocution.
Given the seriousness of the problem, ABYC requirements now include
specific measures for avoiding this danger:
ABYC E–11.13.3.5 states:
If installed in a head, galley, machinery space, or on a weather
deck, the receptacle shall be protected by a Type A (nominal 5
milliamperes) Ground Fault Circuit Interrupter (GFCI).
ABYC E-11.11.1 states:
An Equipment Leakage Circuit Interrupter (ELCI) shall be in-
stalled with or in addition to the main shore power disconnect
circuit breaker(s) or at the additional overcurrent protection
as required by E-11.10.2.8.3 whichever is closer to the shore
power connection.
ELCIs, and the more familiar GFCIs (Ground Fault Circuit Interrupter),
are part of a larger family of devices that measure current flow in the
hot and neutral wires and immediately switch the electricity off if an
imbalance of current flow is detected. ELCIs and GFCIs that are also
RCBOs (Residual Current Circuit Breaker) provide overcurrent tripping
protection characteristic of a normal circuit breaker.
GFCIs are used as branch circuit ground fault protection at the 5mA
threshold in potentially wet environments. GFCIs protect against flaws in
devices plugged into them, but offer no protection from the danger of a
failing hard-wired appliance, such as a water heater or cook top.
In contrast, an ELCI provides additional whole-boat protection. Installed
as required within 10’ of the shore power inlet, an ELCI provides 30mA
ground fault protection for the entire AC shore power system beyond the
ELCI. ABYC regulations still require the use of GFCIs in environments
described above.
Although ABYC regulations apply only to new boat construction, ELCIs can
mitigate dangers and liabilities that exist for any boat owner with a shore
power connection. Retrofitting an ELCI to an existing AC system can be a
worthwhile safeguard against risk. Since an ELCI/RCBO can serve as the
main shore power circuit breaker, it can replace a standard circuit breaker
in this application. Alternatively, an ELCI/RCBO can be added between the
shore power inlet and the existing main shore power
circuit breaker.
Safety ground system failures on boats are safety and liability disasters
waiting to happen. ELCI protection on each shore power line, combined
with protection afforded by GFCIs, will reduce risk to those on the boat,
the dock, and in the water surrounding the boat.
D O C K
GFCI PANEL FOR
OUTLETS IN:
Head, Deck,
Galley, and
Machinery Spaces
ELCI/GFCI Placement Diagram
BRANCH
CIRCUITS
ELCI
SHORE
POWER
INLET
Battery Charger
Air Conditioner
Television
Refrigerator
MARINE POWER
Install
within 10ft
of shore
power inlet
Faulty grounds can be undetectable; a simple continuity test will not
necessarily reveal a problem. When these two conditions occur at the
same time, the results may be tragic. The combination of a ground fault
and a faulty ground can result in metal parts on the boat and under water
becoming energized. If an electric drill with faulty internal wiring or a worn
cord falls into the bilge, the water in the bilge will become energized,
putting the worker and those nearby at risk.
In addition to the hazard to people on the vessel, there is a larger danger
to swimmers near the boat. While people on board are likely to receive
a shock from touching energized metal parts, nearby swimmers could
receive a paralyzing dose of electricity and drown due to involuntary loss
of muscle control.
In addition, a faulty ground can occur when the grounding path is broken
through a loose connection or broken wire. For instance, a shore power
cord ground wire may fail due to constant motion and stress.
However, if electricity “leaks” from this intended path in these two wires to
ground, this condition is called a ground fault. A good example of this is
an insulation failure in the wiring of an appliance.
In a properly functioning marine electrical system, the same amount of
AC current flows in the hot and neutral wires.
Understanding Equipment Leakage Circuit Interrupters (ELCIs) and
Ground Fault Circuit Interrupters (GFCIs) to make your boat safer.
There are two potential failures in a boat’s electrical system that can put
people on or around the boat at risk of lethal electric shock.
*The ABYC has an exemption to this rule if an isolation transformer is used. See E-11 for specific information regarding the exemption.
TECH
tip
by BLUE SEA SYSTEMS