Victron MultiPlus II trips GFCI

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rsicade asked May 20, '24

Victron MultiPlus II trips GFCI

I installed a Victron MultiPlus II 12/3000/120-50 2x120V in my trailer to charge 400AH of LiFePO3 batteries. When I plug everything in and try to charge the GFCI circuit faults. I've tried 3 different GFCI circuits.

With the MultiPlus off, there is no ground fault and I have AC power from the same GFCI outlets.
As soon as I turn on the MultiPlus, the power light blinks, steadies, then I hear a relay click as it tries to charge. GFCI faults immediately
The input current matches the outlet, it is not blowing the breaker on the curcuit.
It happens with all AC output from the inverter off (downstream breakers).
I configured the Inverter's ground relay to 'off', made no difference.
It works normally from a non-GFCI outlet, and from my Honda EU2000i generator.

I can't find enough information from Victron to understand what the ground relay checkbox does from an elecrical standpoint to know if unchecking it should have made a difference. Not sure whether to return this unit as defective and get another one or if I will have the same problem. My dealer says they don't know enough to even have a conversation with victron about this and, in their experience, victron won't talk to customers. Anyone have any insight into this issue?

Multiplus-II

2 |3000

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Answer 1 · 2024-05-20T22:36:37Z

derrick thomas answered · May 20 at 10:36 PM

This is a known issue with the 120v MP2 units unfortunately. The ground relay has no effect on the issue, but it does need to be enabled for mobile installations.

There have been a few people mention success with GFCI outlets by using a dogbone adapter with the ground prong clipped. Not ideal or suggested, but it might get you by in a pinch.

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Alistair Warburton commented · May 21 at 01:01 AM

Absolutely not true in the UK, and likely Europe... Sorry Derrick

There are plenty of folk reading this stuff who simply wouldn't know that things differ around the globe, and sadly a probably couple who will read this and take exception at 'GLOBE'.

Respectfully, general advice on subjects that differ from place to place needs to be qualified as regional, which is why I am not commenting on US REGS.

I would be interested to know what the US REGS are though.
Grounded mobile installations, really?
Would a GFCI be mandatory in that case?
How are fast trip times for sockets handled, an MCB isn't going to work, at least not quickly, not enough fault current potential. We call that Prospective Fault Current in the UK.

I am sure you can google the rest of the acronyms.

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derrick thomas Alistair Warburton commented · May 22 at 03:22 PM

The op has a 120v device, which is marketed and sold for North American markets, so not applicable to UK or Europe, so those standards do not apply. Standards and requirements here in North America are different then they are 'there'. You stick to your knowledge on your side of the pond and I'll stick to mine.

Edit: reading the end of my response here seems like it might come across a little harsh. Not my intention at all. My apologies.

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rsicade commented · May 21 at 03:52 AM

That is consistent with what I have read. It appears it is a difference in GFCI thresholds vs european equivalents. Annoying that I bought this in the US for US use and it it going to have problems with newer electrical installations. Was going to put one of these in my boat next year but my marina is replacing the electrical with the newer ELCI breakers, this thing has no chance of working with shorepower with ELCI's. Since I posted the dealer was going to send the unit to the regional repair facility to have it bench tested but after discussing with the Victron regional manager decided the unit isn't faulty. Waiting for their response, they delayed by asking for a wiring diagram. Only way to ensure this will work with GFCI's and ELCI's would be to install an isolation transformer. Not likely to clip the ground to make it work. Thanks for the confirmation.

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Alistair Warburton rsicade commented · May 21 at 06:27 AM

I am pretty suer that Victron actually sell transformers, for galvanic isolation in marine environments, but a transformer is a transformer, whatever the intended use case.

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Alistair Warburton rsicade commented · May 21 at 06:40 AM

Have you guys got into the GFCI type changes mire and had to deal with AFD's yet?

Type AC RCD's/RCBO's are basically useless now for anything other thana dumb heater.

Type A so AC with half wave detection but only one half and only at 50 Hz are the minimum now here, and its getting worse.

Even a budget RCBO, combined RDC/MCB in Type A at 30mA costs £150, want a type F with AFD, Arc Fault Detection, added, you cam more or less double that.

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Answer 2 · 2024-05-21T00:38:59Z

from... 9. Configuration (victronenergy.com)

Ground relay (see appendix B)

With this relay, the neutral conductor of the AC output is grounded to the chassis when the back feed safety relays are open. This ensures the correct operation of earth leakage circuit breakers in the output. If required an external ground relay can be connected (for a split-phase system with a separate autotransformer). See appendix A.

(I assume that this means is the AC input relays being open)

This whole topic confuses me, 120 0 120 / 240 who cares... If your electrical installation is TNS/TNCS/TNC and you have removed the grid connection with a two pole switch and added another source of power, be that a generator or an inverter then you MUST create a new N-PE bond to ensure there is a low impedance pat that will allow MCB's fuses to operate.

That is what the ground relay is doing, well mostly, chassis was a poor choice IMHO but it is what it is and workable at least. Weather a fuse or MCB has ca cat in hells chance of ever tripping fast enough with such a limited PSC seldom ever gets mentioned. In practice the only way to ensure a fast trip during an earth fault is by protecting everything with an RCD, either separately or using an RCBO.

For TT systems, there is no N-PE bond, in fact the floating neutral is a regular annoyance, causing RCD's to trip when badly designed, lets say Easton derived, equipment creates a path between N and PE.

Additionally, in the UK at least, probably all of Europe, mobile hookups get their own section on earthing.

In essence all mobile installations must be treated as a standalone TT system and have a dedicated earth electrode only for that for that single connection and proximal to it.

Even when the system supplying the mobile connection is itself TT, the site system PE is NOT coupled to the mobile unit.

SO... Unless your standards differ for some reason...

The ground relay is not needed on a TT system and 'could' cause an MCB/GFCI to trip.
Moreover enabling it would mean your system was not compliant, even if it still worked.

For any system...

Everything must be earthed, all earths must be bonded back to the same earth electrode, or grid of electrodes.

If we were talking about a fixed installation, that is not TT, the ground relay would need to be closed when the grid was disconnected to create a N-PE link to replace the one that just disconnected.

Disclaimer... I an NOT an expert on the REGS in the UK and have even less knowledge of REGS elsewhere but I do know what is in play, technically.
You need to check this stuff just to be safe, never mind compliant.

Victron's routes are marine, a whole other ball of wax when talking shore power and boats. I don't know so I am not going to comment on details, but I wouldn't be at all surprised ground connection switching, galvanic isolation and even IT systems made it into that conversation.

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