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Chapter 4
ELCI SYSTEM
TYPICAL ELCI SYSTEM OVERVIEW
The shore power terminates at the power inlet. At this
point electricity when energized travels through a main
ELCI breaker with leakage fault technology to the ship’s
main AC control panel with shore power main and aux-
iliary equipment breakers. The ELCI is located between
the shore power inlet and the ship’s main AC panel break-
ers.
After the shorepower inlet AC electricity travels to each
of the ELCI breakers. The ELCI single pole breaker is set
up to trip should an overload or fault occur between the
breaker itself and the main AC control panel. If the 30
amp ELCI breaker “trips” fi nd the cause of the problem
before resetting the breaker.
The ELCI stands for “Equipment Leakage Circuit Inter-
rupter”. There are two potential failures in a boat’s elec-
trical system that can put people on or around a vessel at
risk of lethal electrical shock. In a properly functioning
marine electrical system, the same amount of AC current
fl ows in the hot and neutral wires.
However, should electricity “leak” from this intended
path in these two wires to ground, this condition is re-
ferred to as a “ground fault”. An example of this is an
insulation failure in the wiring of an appliance.
Furthermore, a “faulty ground” can occur when the
grounding path is broken through a loose connection or
broken wire. As an example a shore power cord ground
wire may fail due to fatigue caused by constant motion
and stress. Faulty grounds can go undetectable; a simple
continuity test may not reveal problems.
When these 2 conditions occur at the same time, it may
produce tragic results. The combination of a ground fault
and a faulty ground could result in the metal parts of the
vessel and underwater gear to become energized. If this
condition exists, besides being a hazard to personnel on
board there is increased danger to swimmers near the
boat. The result could be shocking people on board and
swimmers could receive a paralyzing dose of electricity
and drown due to a loss of muscle control.
Notice that one ELCI breaker is marked shore power
1 and the other ELCI breaker shore power 2.
Another feature of the ELCI is a “leakage fault” detector
located on the side of the ELCI breaker itself. The leak-
age fault feature detects a change in the neutral wire cur-
rent. Should the current change more than 30 milli-amps
or about 1/3 of an amp the unit senses the difference and
will “trip” the breaker causing the leakage fault LED to
illuminate red. This clearly indicates that the trip occurred
as a result of leakage. Before resetting the ELCI breaker
determine the cause of the leakage fault.
A proper operating AC system will display a green illumi-
nated LED at the “power” marked area of the ELCI.
Periodically test the ELCI by depressing the “test” but-
ton. The breaker should “trip” indicating the system is
functioning properly. Simply reset the breaker. The leak-
age hazard helps prevent serious equipment damage and
possible fi re.
After the neutral and the 2-120 volt conductors exit the
ELCI they run directly to the ship’s main AC control pan-
el.
The ELCI can at times undergo a process called “nuisance
tripping” which can cause a tripped breaker. This can be
caused by overloads in the electrical draw or sometimes
from unbalanced loads. One way to minimize the situation
should it occur is to monitor closer the energized devices
on the boat which will assist in keeping the total amperage
used to a minimum and the loads more balanced.
An ELCI provides protection for the entire boat and fea-
tures a trip threshold of 30mA which provides ground
fault protection for the entire shore power system beyond
the ELCI.
The ELCI protection on individual shore power lines
combined with GFCI’s will reduce the risk to those on
the boat, dock, and in the water surrounding the vessel.
TYPICAL ELCI
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