GFI Shore Power - my boat won’t connect!?!?

[malyea]

My boat accepts shore power (50A pigtail splits to two 30A lines) except at a marina with “new style GFI shore power”. Everything is turned off (don’t have an inverter), I plug into power pedastal, flip on the shore power pedastal switch, then flip on the two main AC breakers on the boat panel (everything is off) - and the pedastal CB pops and I can’t connect to shore power - until I get to a marina with an ‘old style non-GFI power source’ - then everything is fine... How best troubleshoot this? What other threads have covered this? How common is this issue involving “new style GFI shore power pedastal”? Thanks!

[Thumbs Up]

If the pedestal has a 5ma gfci then your wiring may still be within specs but if you are popping a 30ma gfci then you have a safety issue especially if you are in fresh water. These pedestals are designed to prevent electric shock drowning. You have a ground fault which means that you are probably leaking current into the water. It could simply be caused by grimy components

[malyea]

I suspect troubleshooting this issue is probably beyond me - so now looking for a qualified marine electrician (while studying the topic so as to be able to “vet” a qualified electrician). Thanks

[mrm]

Originally Posted by malyea

I suspect troubleshooting this issue is probably beyond me - so now looking for a qualified marine electrician (while studying the topic so as to be able to “vet” a qualified electrician). Thanks

Studying is good, helps in being self-sufficient :-)

An undamaged GFI breaker will trip for two reasons:

1) a current difference between L (live) and N (neutral, sometimes called return) wire. In a properly functioning AC circuit current flows only in L and N conductors and is exactly equal. PE (Protective Earth) carries no current, unless there is some fault (leakage).

2) GFI breakers are designed to detect a short between PE and N in the part of AC circuit after the breaker and trip immediately. This way the protective functionality of PE conductor is tested and enforced.

Checking for cause no 1 is best done with help from a professional. Cause no 2 can be detected using a simple multimeter.

[Colin A]

Yeah may need pro help. As a starting point have some times seen main breakers with a rev polarity trip (shuts down boat on rev polarity instead of a simple warning light) cause issues with ELCI GFCI.

[cyan]

I think the marine electrician is the best path, but have you tried a few simple checks at the "new style" GFCI yet?
1. Borrow a neighbor's shore power cord and see if the more sensitive GFCI still trips.
2. Do you have a reverse polarity indicator light? Is it lit?
3. Do you have a galvonic isolator? Is it in a wet/dirty place?

The good news is that it sounds like you have already narrowed down the issue. I suspect the electrician will simply open your sub-breaker panel and disconnect each neutral from the buss one by one (with all open) until the problem stops, then track down the offending device/wiring.

[Stu Jackson]

This is not something completely new:

Don't Get Tripped-Up by New Shore Power - Updated

[malyea]

Originally Posted by cyan

I suspect the electrician will simply open your sub-breaker panel and disconnect each neutral from the buss one by one (with all open) until the problem stops, then track down the offending device/wiring.

I hope it goes that easy once I locate a qualified marine electrician.

I have to move from my current slip to the new slip in a couple weeks. Current slip is “old style non-GFI shore power” that connects fine to my boat without problem - new slip has “new style GFI shore power” that won’t connect without tripping...

Question - should the electrician first troubleshoot boat in the current slip with fully powered up AC circuit (non-GFI) or move the boat to the new GFI slip and troubleshoot only in the new slip but without the boats AC circuit powered?

Thanks

[Stu Jackson]

Originally Posted by malyea

Question - should the electrician first troubleshoot boat in the current slip with fully powered up AC circuit (non-GFI) or move the boat to the new GFI slip and troubleshoot only in the new slip but without the boats AC circuit powered?

Thanks

The issue could well be something completely out of your control. Have you read the link I earlier provided? One of the many suggestions is this one:

NEC building code does not require GFI protected breakers at each power stanchion. Marinas may instead put a single GFI protection device at the main power feed to a section of the marina. If this is the case, there will be an over-amperage breaker with the normal over-amperage reset. However, there will be no reset for a GFI trip. Instead, any excessive amperage leakage will trip the single GFI device and turn off power for the entire section of the marina and marina staff will need to be notified to correct the problem.

Not clear if that's your case or not.

[malyea]

Originally Posted by Stu Jackson

The issue could well be something completely out of your control. Have you read the link I earlier provided? One of the many suggestions is this one:

NEC building code does not require GFI protected breakers at each power stanchion. Marinas may instead put a single GFI protection device at the main power feed to a section of the marina. If this is the case, there will be an over-amperage breaker with the normal over-amperage reset. However, there will be no reset for a GFI trip. Instead, any excessive amperage leakage will trip the single GFI device and turn off power for the entire section of the marina and marina staff will need to be notified to correct the problem.

Not clear if that's your case or not.

No, not my case. Power trips only at the new GFI protected power pedastal located at the single slip only - not for an entire section of marina.

[cyan]

Originally Posted by malyea

Question - should the electrician first troubleshoot boat in the current slip with fully powered up AC circuit (non-GFI) or move the boat to the new GFI slip and troubleshoot only in the new slip but without the boats AC circuit powered?
Thanks

The marine electrician should have a leakage clamp probe (NOT an ordinary current probe) which will most likely quickly unravel the mystery in the existing slip with the powered circuit. (if the troublesome wiring is accessible)

The slip where the GFCI is tripping might take a little longer but could be done in a simpler fashion. (disconnecting wires one by one)

From your description, my guess is that the culprit is a large circuit breaker that is remote from the main panel. I would put money on a dirty windlass breaker/wiring or similar one that is not on the main panel. (or fridge, aircon, ect.)

It has already been stated, but this is very important to solve, as stray current of even a few mA can cause drowning by adverse muscle effects to nearby swimmers or bottom cleaners.