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stan-moore-rainczuk avatar image
stan-moore-rainczuk asked

MultiPlus-II and GFCI tripping in home backup mode.

I read all I could find about the subject of GFCI tripping when using MultiPlus-II but, I couldn't find any information that would match my situation.

My hope is to use this system as a home backup in case of outage and as a cost cutting during high peak hours. (Use power from my batteries for some circuits during high peak hours and recharge the batteries after midnight in off peak hours)

I have a 4 circuit transfer switch installed next to my sub-panel inside my laundry room by an electrician. The MEN is at the main panel in my condo complex.

MY SYSTEM IS MOBILE (A WOODEN SHED ON RUBBER WHEELS WITH NO EARTH GROUND.

IT WILL BE ALWAYS USED CONNECTED TO THE SAME AC SOURCE AT MY HOME AND NOT MOVE AROUND OR USE ANY OTHER AC INPUT.

Here is my problem:

1-The problem I have is that every time I try to use the GFCI outlet (at my patio) and the AC out1 line of my MultiPlus-II out to my transfer switch together- the GFCI outlet I am using trips.

2-The MultiPlus-II works fine charging the batteries and inverting at the same time as long as I don't connect AC out1 to the transfer switch.

3-The AC out1 from my MultiPlus-II to my transfer switch circuits works fine as long as the AC-in is not connected.

4-The charging of my batteries works fine from my patio GFCI outlet by itself.

5-If I plug in the system inside my home outlet without GFCI everything works fine. I can charge the battery and pass through the AC to the transfer switch without any problems at all, but I have to use the outside outlet and it has to be GFCI protected. (The inside outlet I tested with is on circuit that is not on the transfer switch of course)

6-The system has no errors or any notification of problems.

Do I need my ground relay on or off if I always will be connected to my house outlet?

Even if my grid goes down my ac ground from the house still would be connected to my system, wouldn't it be?

Multiplus-II
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8 Answers
tom w avatar image
tom w answered ·

Does your transfer-switch switch both live and neutral or do you have a common neutral for the grid and AC1 out?

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stan-moore-rainczuk avatar image
stan-moore-rainczuk answered ·

Hi Tom, I am not sure I understand what you are asking. My transfer switch at home is typical Reliance Pro Tran2 and my MultiPlus-II AC line in and AC out1 terminals are connected as recommended.

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tom w avatar image
tom w answered ·

Hi Stan,

The neutral in on AC-In is different from the neutral of AC-1-OUT of a Multiplus and must not be connected together. When you switch a circuit between grid and AC1-OUT you need to switch the neutral wire as well.

From all that I found about the Tran2, it is only switching live wires. The neutral wires are all connected together in bus bar. That can cause residual currents between AC1_OUT and the grid.

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stan-moore-rainczuk answered ·

Thank you Tom for replying so quickly. Am I the only one trying to do what I hoped was a simple use of the very well accepted equipment in the home backup?

I was hoping that the MultiPlus-II would run 4 circuits from the batteries and top them off in a Off peak hours after midnight. My 4 circuits would be powered by the inverter and a AC timer on the line in would connect to my home outlet automatically between 12am and 6am to recharge the batteries (I have limited number of solar panels because it's Condo and I only use solar on my patio.)

Is there any thing I can do to have this configured safely and work as I hoped it would.

Like I said I can charge the battery from my outlet just fine without GFCI blowing. And after I disconnect my AC in I can connect to my transfer switch and it will run my circuits perfectly. But if I connect my AC in while the AC out1 is connected then my AC-IN gfci trips.

Thank you again for taking the time to help me.

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tom w avatar image
tom w answered ·

The Multiplus 2 has an internal transfer switch that can solve your problem. Instead switching the circuits with an external switch, you hook all of your circuits you want to be battery powered to the AC1-OUT and use a Cerbo or Venus GX to control the switching between grid for charging and discharging during the day.

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stan-moore-rainczuk answered ·

How can I do this? My MultiPlus-II is in the outside shed and my circuit sub-panel is in my laundry room. I assume you are referring to the Victron ESS, am I correct?

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tom w avatar image
tom w answered ·

Yes, I'm referring to an ESS.

ESS provides scheduled charging and AC1-Out can be programmed to Inverter only. However, it requires that you have a separate cable from the grid to the Multiplus and another cable from AC1-OUT to your breaker panel, so you don't share neutral in/out. I guess that is not the case for your installation.

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stan-moore-rainczuk answered ·

Yeah, That's not a solution for me. I guess I will have to run my transfer switch circuits alone and disconnect them before recharging the battery. Too bad that Victron can't automate this process for setting like mine.

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