Shore Power Tripping GFCI breaker

[vineyardgray]

I have moved my boat from the TrentPort Marina in Trenton to the Port Credit Yacht Club in Port Credit and now have an issue with my shore power.

The TrentPort Marina does not have GFCI breakers which I'm pretty sure is the issue. PCYC does. I have to 125V 50A shore power socket inlets to the boat one that has the house-side of the panel on it. The other side of the panel only has two Air Conditioning units and associated water pumps. Shore power is two 30A. This shouldn't be an issue because I can connect the Air side and the breaker for that shore power circuit does not trip, even with both AC units operating.

The house side, however, trips the breaker immediately. I have tried even without all the breakers off and no dice.

Spent yesterday with the multimeter and found DC bleeding into the AC side of the panel somehow between ground and neutral through the Fore Bilge Pump. With that off, I can finally power up the House side of the panel with the Battery Charger switched off and the salon outlets, but it only held for half hour or so before tripping again.

I looked for major issues with the wiring and can't see anything obviously incorrect.



Boat is a 1988 Carver Santego.

[bud37]

Try to completely disconnect your charger AC wiring and see what happens......I had an issue once with another boat , kept tripping the shore off ,had continuity between white and green safety ground...... isolated every AC circuit and tested for continuity ( took a long time ) and found one with short from neutral to ground, was the last one tested ....small nick in white wire was touching the receptacle box ( they used metal boxes )..... fixed that and problem gone.

Check all your appliances as well, isolate as much as possible.

[bud37]

Another read here...this guy has some real good info, well explained.....
..https://gilwellbear.wordpress.com/categ ... for-boats/

[vineyardgray]

Thanks Bud, I did have a read through that article.

I'm here now trying to sort this out.

My results yesterday were short lived. Today the breaker trips immediately.

I also was testing with the shore power cord attached (breaker off) so DUH there was head scratching continuity between ground and neutral. Funny how a nights sleep can highlight the error of ones ways. I also think the DC I was seeing was due to the short power somehow. Or maybe the leaking fwd bilge pump only has somewhere to 'leak' to when the shore power ground is connected?

So I have to say - the layout in this electrical panel is pretty well done. Separate bus bars for neutral and ground per panel side.

So here's what I did to confirm that neutral and ground are separate -

1. Disconnect Shore Power Cable
2. Switch to Shore Power
3. Stick test probes on neutral and ground busbars
4. turn on Line 1 main breaker
5. switch on each circuit breaker one at a time

At no point did I get continuity between ground and neutral.

Any flaws in this approach?

[bud37]

So just a thought, have you made sure the marina pedestal is ok ? On the rest of the site where that info came from is quite a bit of other info/ testing that may help you here.....the relationships on a boat are a bit confusing, it seems at this point you have the right approach. Did you completely disconnect the charger....that is one place where a short can cross over I believe, Im not saying that is it, just what I would try, do you have an inverter ?

How are you getting from the 30amp shore to the 50amp boat side ?

[vineyardgray]

Hi Bud - It's dark now so I'm not going to disconnect the charger today. I'm using an adapter to go from 30a to 50a. I will go meter the marina pedestal now. It is starting to look like the charger as you say... read on:

Scratch what I said about the neutral/grd. The beeper gizmo on my multimeter must have been turned off or something.

I'm going to document this whole journey in the hope that it helps some other poor SOB someday.

So I DO have continuity on the following circuits when the breakers are closed "on":

Range
Microwave
Battery Charger

So my trouble is there somewhere I presume.

Here's the interesting part.

Range - dead short between neutral and ground. Something is wired wrong there.
Microwave - this isn't a short exactly, a varying resistance of around 250 ohms. Strange.
Battery charger. Started as an audible short then started increasing in ohms. The longer I hold the meter, the longer It increases in resistance. WTH?

[vineyardgray]

Spent today messing around with it and wish I had happier news to report.

Symptoms are intermittent but same as before - can only turn shore power on for short periods of time and only for certain circuits. Then for no apparent reason pedestal breaker trips open.

There is about 50 to 85mV of DC between the neutral and ground when connected to shore power. I'm not sure the GFCI takes DC into account but that does seem suspicious.

Also the main breakers on the carver are 3 pole, the top pole of mine being wired into the polarity indicator light. One side of this pole is wired to ground and the other to neutral. This seems wrong, but why do I not show continuity between the ground and neutral with the main breaker closed 'on'? I checked continuity between the breaker and it shows no continuity on this pole in either open or closed position. Tried the other main breaker. Same condition. Are these main breakers euchred?

Tried an unused 50A 125/250 pedestal nearby and no change - immediate trip. The problem is on the boat.

[vineyardgray]

Forgot to mention, I did fully disconnect the battery charger as bud suggested.

[tomschauer]

Check the galvanic isolator. That's where your d/c and a/c meet via ground.

[bud37]

If you are fully convinced you have power in the safety ground then that will trip the breaker in my opinion. You will have to systematically isolate each and every appliance and leg to properly test for continuity between green and white......did the charger test out ok disconnected ( power off ).

Check your panel as to how the bonding system is connected in there and test it for DC voltage.Without being there it is bit of a crap shoot, hope you dont get led in the wrong direction, if so my apologies up front.,,,,good hunting....