Electrical Question for any Guru

[NorthernFocus]

When parked at home on the trailer I have my shorepower cord plugged into a GFI protected 110 receptacle in my garage. If I turn on some of the 12V loads on the boat the GFI in the garage will trip. Anyone have any idea how this can be happening? I assume this means that the 110 circuit on the boat is wired to the same common ground as the 12V system?

 

[scross]

I am not an electrical guru so take this with a grain or bucket of salt. The GFI in the garage will trip if it experiences more current passing through it than is coming back from the appliances turned on. What I have experienced is that the GFI outlets or GFI breaker can also trip it is passing through more current than it is rated to handle. If you plug two hair dryers into the garage GFI outlets and turn them both on to high then the GFI breaker or GFI outlet may trip.
I assume you are not getting a reverse polarity light on your shore power voltage indicator. If you are getting a reverse polarity indicator light then this may well be the problem and needs to be addressed right away. If you are not getting a reverse polarity indicator then something else happening.
You mentioned that you are not using the 110 volt outlets in the boat and the GFI outlet is tripping just by turning on 12 volt systems. On shore power you are using battery for the 12 volt boat circuits but running the battery charger. If you are drawing a lot of current from the batteries by what you are turning on in the boat that might be causing the battery charger to "work harder" and cause the GFI outlet to trip. You may want to test the GFI outlets in the garage. It's been my experience with those that they fail they failed they “get old” by tripping at the slightest load - which is a good way to fail. I've probably replaced 10 GFI outlets in my houses over the years.
Any guru out there please correct me if I have any of this incorrect.

 

[Red Raven]

Not a guru by any means but I think I do know how a GFCI works. A GFCI does not work like a regular breaker. It does not trip due to exceeding a load limit. It trips when the current in the hot wire is different than in the neutral wire. It takes a very small difference to trip (around 5 milliamperes) because it is designed to protect people using a single circuit. It trips in your garage when you turn on loads in the boat because the difference in hot to neutral is exceeded when you turn on all those loads in the boat. It means there is a current path to somewhere other than where it is supposed to be (the neutral). It doesn’t matter whether the safety grounds (bare or green wires) are shared or not. Some amount of current is leaking, somewhere. It may be because your boat is outside and there may be some water or contaminants on or near either end of the shore power plug. In any case, a GFCI is not intended to be used for protecting a whole boat electrical system. That is what the ELCI is for on your boat. An ELCI typically trips at a more forgiving 30 milliamperes and is designed to protect equipment (as opposed to people) and thus the need for additional GFCI’s on the boat itself to protect the people.

Plug your boat into a non-GFCI protected outlet. The ELCI on the boat will protect the equipment and the GFCI’s will protect the people unless incorrect alterations have been done to the boat. Maybe a marine electrician out there can confirm.

 

[Favunclerich]

This problem is common on older R-25's and has been discussed in previous threads. The fix involves unplugging the boat, removing the AC panel and cutting one particular wire. Please search the older posts for a description of how to identify the wire that is to be cut.

 

[knotflying]

I seem to remember having this problem on my R-27 way back when. I resolved it by plugging into a regular outlet. :lol:

 

[BB marine]

There are a few things that can cause this. Bad main breaker, polarity light, any voltage source leaking into the ground lead. If the GFCI senses any voltage on the ground (green) it will trip. From a few post it seems like a issue has been there and not caused any problems I would agree with Knotflying.
.

 

[DBBRanger]

This problem is common on older R-25's and has been discussed in previous threads. The fix involves unplugging the boat, removing the AC panel and cutting one particular wire. Please search the older posts for a description of how to identify the wire that is to be cut.

Same on my 2008 R25. There's a wire connecting ground on the 12v side to ground on the 110V side that needs to be removed. I don't remember the details but there are discussions in the archives.

 

[NorthernFocus]

There are no load issues involved here. For example, turning on the anchor light (1.5W LED bulb) will cause the breaker to trip. Which suggests to me that it's an issue with the ground side of the circuit. Unfortunately the obvious solution of plugging into a non-GFI circuit would require quite a run of cable.

This problem is common on older R-25's and has been discussed in previous threads. The fix involves unplugging the boat, removing the AC panel and cutting one particular wire. Please search the older posts for a description of how to identify the wire that is to be cut.

Thanks I'll see if I can hunt it down.

 

[Red Raven]

This problem is common on older R-25's and has been discussed in previous threads. The fix involves unplugging the boat, removing the AC panel and cutting one particular wire. Please search the older posts for a description of how to identify the wire that is to be cut.

If there is a connection between the neutral and grounding wire anywhere past the transfer switch (switch to select shore power, gen, inverter, etc.) that would definitely explain the symptoms and would also be a safety issue. Since the panel in homes typically has this connection I can imagine someone making the mistake in the boat’s AC panel. If so, it is a problem and would need to be corrected as it would allow current to travel back to the shore connection in the grounding wire instead of the neutral return and thus setting off the GFCI. The generator and inverter will have this connection (as they should) but they are isolated by the transfer switch When not in use.

 

[NorthernFocus]

This problem is common on older R-25's and has been discussed in previous threads. The fix involves unplugging the boat, removing the AC panel and cutting one particular wire. Please search the older posts for a description of how to identify the wire that is to be cut.

I wasn't able to find the specifics regarding which wire in the AC panel needs alteration. However, in the process of looking for it I read plenty of the detailed explanations that I should be able to sort things out. I have neither generator nor inverter so as I understand it there shouldn't be any AC wiring landed on the DC ground on the boat. The AC system bonding should be via the shore circuit. That should be simple enough to sort out. Maybe not easy, but simple(not necessarily one and the same).

 

[Red Raven]

...so as I understand it there shouldn't be any AC wiring landed on the DC ground on the boat. The AC system bonding should be via the shore circuit. That should be simple enough to sort out. Maybe not easy, but simple(not necessarily one and the same).

To clarify, it is the AC neutral (and obviously the hot) that must be isolated from the bonding system and the AC grounding wire except at the power source (in the shore power system). The boats bonding system and battery negative absolutely should be tied to the AC grounding wire either directly or through a galvanic isolator. It is only the misconnection of the AC neutral to grounding wire at issue here.

 

[knotflying]

Unfortunately the obvious solution of plugging into a non-GFI circuit would require quite a run of cable.

Not knowing the configuration you have for your garage GFCI, but either install a new standard outlet near the GFCI fed from the feed side to the GFCI or temporarily replace the GFCI with a regular outlet. Granted this would defeat the purpose of a GFCI, but at least your immediate problem is resolved until you find the culprit.

 

[NorthernFocus]

...Not knowing the configuration you have for your garage GFCI, but either install a new standard outlet near the GFCI fed from the feed side to the GFCI or temporarily replace the GFCI with a regular outlet. Granted this would defeat the purpose of a GFCI, but at least your immediate problem is resolved until you find the culprit.

That was my first thought but we're in a rental home and I'm not keen on altering something would create a code violation. Plus it just pushes a problem down the road for another time/place. That's certainly the simplest immediate solution.

 

[Red Raven]

Dan,

Here is the thread referred to above:

http://www.tugnuts.com/viewtopic.php?f=6&t=769&p=5283&hilit=Neutral+grounding#p5283

Apparently at one time an incorrect connection was made between the battery negative and AC neutral at the AC Volt meter.

Here are the particular instructions from Andrew on what wire to cut. If you have such a connection or. Your boat it would explain the GFCI trip problem. Remove/cut it if it is there.

...

Re: R-25 120V Panel tripping GFCI Outlet
Postby Andrew Custis on Tue Dec 29, 2009 5:01 pm

The black wire, just as I suspected is the grounding wire that ties into the 12volt meter. This makes the ground connect for the backlighting on the meter. The one I looked at today was able to be cut and left alone. The guys had it grounded into the neutral circuit causing a GFI to break. If you experience this problem, I would cut that black wire and cap it off not allowing it to touch any other wires.

...

 

[NorthernFocus]

Dan,

Here is the thread referred to above:

http://www.tugnuts.com/viewtopic.php?f=6&t=769&p=5283&hilit=Neutral+grounding#p5283

Apparently at one time an incorrect connection was made between the battery negative and AC neutral at the AC Volt meter.

Here are the particular instructions from Andrew on what wire to cut. If you have such a connection or. Your boat it would explain the GFCI trip problem. Remove/cut it if it is there.

...

Re: R-25 120V Panel tripping GFCI Outlet
Postby Andrew Custis on Tue Dec 29, 2009 5:01 pm

The black wire, just as I suspected is the grounding wire that ties into the 12volt meter. This makes the ground connect for the backlighting on the meter. The one I looked at today was able to be cut and left alone. The guys had it grounded into the neutral circuit causing a GFI to break. If you experience this problem, I would cut that black wire and cap it off not allowing it to touch any other wires.

...

Awesome. Thanks for this. The thing that's puzzling about the issue is that there are only certain 12V loads that cause the problem and not necessarily large ones e.g. the 1.5W LED anchor light. Yet I can start the Webasto with associated load of the glow plug without tripping the GFI. But armed with this info I'll check it out.