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Nobadays
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# Posted: 9 Dec 2025 05:17pm - Edited by: Nobadays
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Okay smart people! I need help with this one!
No good place to mount a Victron 12/1200 inverter in our campervan - and I wanted the option for a stand alone power station - so I have built two boxes that fasten together. One has the inverter and outlets, the other two 100ah lithium batteries, scc, fuses etc. Both have Anderson plugs so they can be connected.
I wired an Anderson plug to the battery busbars in the van to have power accessible to plug just the inverter box into. (NOTE: The inverter box powered by the van or its companion battery box will power anything I plug into it, without any problems.)
Here is the problem: When I plug the shore power cable from the van into the inverter box outlets it immediately trips the GFCI breaker on the Victron inverter. I have the van's converter/charger turned off but it trips it with it on or off. I turned all the breakers in the van off except the main thinking one circuit might be bad, nope still trips.
I started the generator and plugged a circuit tester into all the 120v outlets, all good. Next I plugged the van into shore power and checked the outlets, all good.
Next I ran a ground wire from the inverter and clipped it onto the tailpipe figuring that should be a good ground. Same thing, tripped the GFCI.
Edit: This Victron inverter is default floating ground.
Any thoughts? Thanks!
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MtnDon
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# Posted: 9 Dec 2025 10:23pm
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It sounds like there may be two neutral-ground bonds in what you have as a system. Two separate bonds could cause an imbalance in current flow. If a GFCI senses an imbalance between current flow in the hot and neutral wires it is connected to, it will trip. By design it only takes 4 to 5 milliamps to cause a trip.
The second bond could be a short somewhere between a neutral and a ground. An accidental short, not an intentional bond.
A reversed ground/neutral would also trip the GFCI. The circuit testers should find any error, BUT, banging around in my head is some vague recollection that there can be situations when the three light testers can fail. But no details come to mind. I am a sometimes handy person and sometimes don't recall the details.
The inexpensive three light testers have their limitations and can deliver false results.
There are testers, costing more, than can detect these tricky things.
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Brettny
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# Posted: 10 Dec 2025 07:48am
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GFCI is looking for equal parts power in/out. So of your neutral is grounded any where this can happen. You will need to open up the 120v power box in the camper and make sure the neutral and ground wires are separate.
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Nobadays
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# Posted: 10 Dec 2025 09:48am
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Quoting: MtnDon It sounds like there may be two neutral-ground bonds in what you have as a system.
This was my thoughts too.
Quoting: Brettny So of your neutral is grounded any where this can happen. You will need to open up the 120v power box in the camper and make sure the neutral and ground wires are separate.
Thanks guys... I hope this is what it is and not somehow related to the transfer switch. They put solar inverters in RVs all the time but usually they use another/different transfer switch so there can be three power sources. I'm just hoping to get away with plugging the shore power cable into the inverter box I built.
I guess I dig deeper! Thanks for a direction to turn!
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travellerw
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# Posted: 10 Dec 2025 11:28am
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Are you sure you are tripping GFCI and not AFCI?
I'm pretty sure Victron inverters have AFCI protection. Its possible that its detecting an arc from something in your van, or even from the act of plugging in the cable.
I would try plugging in with the Victron powered down (with the battery disconnected), then powering it up. If that works, then its AFCI for sure.
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Nobadays
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# Posted: 10 Dec 2025 02:41pm
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Thanks again! My brain was leaning towards a neutral-ground or ground-neutral. Turns out it was the ground wire to the plugin for the converter/charger that was tied to the neutral busbar. (See picture) Why this was I don't have a clue because there is a ground busbar there as well. I just moved the wire to the ground busbar and presto! my inverter box now powers the van!
Travellerw.... some Victron inverters may have an AFCI, this 12/1200 has a GFCI.
Thanks for the help guys!
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Brettny
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# Posted: 11 Dec 2025 09:16am
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Awesome job! Easy fix and no parts needed.
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travellerw
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# Posted: 11 Dec 2025 09:55am
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Quoting: Nobadays Travellerw.... some Victron inverters may have an AFCI, this 12/1200 has a GFCI.
It dawned on me that you meant the Physical GFCI on the inverter. Some Victron don't have Physical GFCI outlets, instead its in software. Both GFCI and AFCI. When tripped an output light will blink and you need to power the inverter down for about 30 seconds to reset. The blink pattern tells you which one tripped.
Anyway.. Glad you got it solved.
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gcrank1
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# Posted: 11 Dec 2025 10:11am
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Another WIN for our Amazing Brain Trust here 
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