Newer boats 2012 and up must meet ABYC regs and that a ELCI breaker 30amp (RDC) be installed on main line into boat trip on 30ma within 100mlsec. This is in addition to the main usually 30amp breaker. Most insurance companies are now requiring they be installed on older boats. When they first came out many were part of the shore power inlet ,but are now a separate panel. I installed mine in panel at nav desk before main AC panel on a DIN rail. If boat has Isolation transformer it must be installed within 10 ft of shore power inlet
Its similar to a GFI ,however the neutral and hot wire must be balanced within 30ma or it trips usually a ground fault. A GFI plug trips at 5ma . This is to stop people in marinas from getting fried going into the water from leakage from a boat. If your boat kills someone you could be held liable
ABYC E11.11.1
An Equipment Leakage Circuit Interrupter (ELCI) or Type A Residual Current Device (RCD) 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.
EXCEPTION: Installations where an isolation transformer is installed within 10 feet (3 m) of the shore power inlet or the electrical attachment point of a permanently installed shore power cord and supported according to
11.14.4.1.3
11.11.1.1 The trip level shall be a maximum of 30mA. The trip time shall be a maximum of 100ms.
11.11.1.2 This device shall meet the requirements of UL 1053 Standard for Safety for Ground-Fault Sensing and Relaying Equipment and the requirements of UL 943 Ground Fault Circuit Interrupters with the exception of trip level, trip time, and grounded neutral detection or
11.11.1.3 IEC 61008, Residual current operated circuit-breakers without integral overcurrent protection for household and similar uses or IEC 61009 Amendment 1 - Residual current operated circuit-breakers with integral overcurrent protection for household and similar usesand IEC 61543, Residual current-operated protective devices (RCDs) for household and similar use - Electromagnetic compatibility.
NOTES:
1. Trip levels of less than 30mA and times of less than 100ms may result in nuisance trips in certain environments.
2. If included, the circuit breaker must also meet the requirements of
E-11.10.2.
3. IEC compliant RCD’s must be rated for 125, 250 V 60Hz applications.
11.11.1.4 The ELCI or RCD shall be readily accessible.