AC Ground Faults and ABYC Approved ELCIs

Tim & Dave Kinghorn

The ABYC has amended its standards to allow a 30ma Equipment Leakage Circuit Interrupter (ELCI) on the shore power input to the boat and requires it on new boats.

I've never liked connecting the DC ground to the AC grounding circuit. With the use of an ELCI, this would not be needed. In addition, to having to deal with potential corrosion problems when the two are connected (therefore, the need for galvanic isolators), it raises the possibility of electrocution when the boat is on shore. If the AC were to short to the grounding wire and the circuit breaker for main power doesn't trip, any connected DC grounds could be hot (Motors, etc.).

Nigel Calder brought it to my attention via the August 2010, issue of Sail Magazine (P.60).

Go to: http://bluesea.com/viewresource/1381 for an excellent, short (one page) summary.

Blue Sea carries the approved ELCI. PN 3102 (30ma) for a 30A AC Main.
Also called a Residual Current Rocker Circuit Breaker (RCBO).

Tim & Dave Kinghorn

Tim & Dave Kinghorn

The price for a 120V, 30A (30ma leak detector) is around $200. The Blue Sea PN is 3102. All the usual suspects can get it. In Seattle: Boat Electric, Fisheries, West Marine, etc. can get it. Check around, the price does vary.

Tim & Dave Kinghorn

sjboysen · Posted: Mon Aug 02, 2010 7:45 pm Post subject: ELCI and wiring

Just to clarify as I want to make sure that information being posted on the Cbrats page is correct, in regards to the ELCI wiring, ABYC STILL recommends that you keep the DC ground wire to AC ground circuit intact even while using an ELCI.

I hope that this information is helpful and please don't hesitate to contact me direct for clarification.

Sincerely,

Scott Boysen

Mike...

Tim & Dave Kinghorn · Posted: Mon Aug 02, 2010 10:31 pm Post subject: AC Grounding to DC Ground

Scott,

You are absolutely correct. We'll have to see if they (ABYC) drop this policy now that they've accepted the European model for the ELCI.

Thanks for catching my error, and I'm pleased you're reading posts with a critical eye for misstatements.

I still don't like connecting the AC grounding to the DC ground. I use a galvanic isolator on the AC grounding return to reduce the chance of corrosion, but I'm not an electrical engineer. Perhaps there is a good reason to continue this policy.

Tim & Dave Kinghorn