bluesea.com CIRCUIT PROTECTION 86 ELCI detects that current is not balanced and opens (trips)—breaking circuit FAULTY GROUND Marine Electrical System 20 AMPS 19.970 AMPS SHORT LIMITED TO 0.030 AMPS (30mA) 19.970 AMPS THROUGH LOAD 19.970 AMPS 20 AMPS CURRENT COIL POTENTIAL HAZARD BROKEN GROUND ENERGIZED SURFACE HOT NEUTRAL GROUND 120 VOLT 60 Hz POTENTIAL HAZARD OPENS WHEN AN IMBALLANCE IN CURRENT IS DETECTED ELCI detects that current is not balanced and opens (trips)—breaking circuit 20 AMPS 19.970 AMPS CURRENT LEAKING TO GROUND 0.030 AMPS (30mA) 19.970 AMPS THROUGH LOAD 19.970 AMPS 20 AMPS OPENS WHEN AN IMBALLANCE IN CURRENT IS DETECTED GROUND FAULT Marine Electrical System CURRENT COIL 0.030 AMPS (30mA) CURRENT LEAKING FROM HOT WIRE HOT NEUTRAL GROUND 120 VOLT 60 Hz ELCI detects that current is balanced and remains closed—completing circuit 20 AMPS 20 AMPS 20 AMPS THROUGH LOAD 20 AMPS 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 installed 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. An 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. AC Ground Faults ELCI, the Boater and ABYC TECH TIP
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