Off grid inverter to residential breaker box? Tripping GFCI?

[ericfx1984]

I have an Aims power 3,000 W inverter...

That is hooked up hardwired to my RV (30 amp)

I'm also building a completely off-grade house and I just finished the 120 side of the electrical

I figured the easiest way to test the 120 circuits was to install a double breaker (normally used for 240v) to backfeed the 120 hots into that breaker effectively bonding both sides of the breaker box

When I first plugged it up even with all the breakers off it immediately tripped the GCFI on the inverter

I also tried this test using my generator which also had the same problem

So I figured it had to be something on either the neutral or ground side of things... I figured this was the case since all of the hots were switched to off

I quickly discovered that it was an issue with the breaker box having a bonded neutral

The only way that I could actually get power to go through the breakers was to disconnect the ground feed going from the generator to the breaker box

Since this is not going to be hooked up to grid ever, what is the best way to do this? I'm guessing I would want to install a proper ground rod for the house and tie the inverter to that ground rod as well as the house to the ground rod? I guess this is the part I'm having a little trouble understanding?

With the RV I simply let the inverter handle the ground side of things and everything just sort of works and maybe that's the answer

Anyway I'm not quite sure I would love to have someone's opinion

 

[Ampster]

I figured the easiest way to test the 120 circuits was to install a double breaker like you would use for 240 volts to backseat both of the 120 hots into that breaker effectively bonding both sides of the breaker box

I am not sure what the term, "backseat" implies and how that bonds both sides of the breaker box. If you are refering to L1 and L2 that is different than bonding the ground and neutral at the main panel. I would disconnect one side of the L1 or L2 legs and diagnose from there which leg is causing the GFCI to trip. There are testers you can buy to identify the faults.
EDIT:
I responded before I completely read the entire post. Yes, I think you need a ground rod at the house for starters. Then test from that standpoint. The ground and neutral should be bonded at that main breaker but if the generator works without the ground then that is part of the solution.

 

[ericfx1984]

I am not sure what the term, "backseat" implies and how that bonds both sides of the breaker box. If you are refering to L1 and L2 that is different than bonding the ground and neutral at the main panel. I would disconnect one side of the L1 or L2 legs and diagnose from there which leg is causing the GFCI to trip. There are testers you can buy to identify the faults.

That should have said backfeed... I fixed the original post

So it's like this

120v Inverter GFCI >>> extension cord >>> USA breaker box

Both hots in the box are bonded via a jumper for testing(basically turns a 240v/120v box into a 120v only box)

Neutral and ground are bonded in the box

With the ground coming from the inverter to the breaker box disconnected everything works

 

[Ampster]

So it's like this

Okay that makes more sense. I have heard of people tying both sides of a panel together to creat a 120 volt panel. Removing the ground at the inverter sounds like it solves the problem. I would still drive a ground rod and connect that to the panel in the home.

 

[ericfx1984]

Okay that makes more sense. I have heard of people tying both sides of a panel together to creat a 120 volt panel. Removing the ground at the inverter sounds like it solves the problem. I would still drive a ground rod and connect that to the panel in the home.

It's just for a temporary test at this point... I'm going to probably start in the next few weeks on building the actual house inverter system

It's going to start out at 6,000 Watts with a 120/240 inverter. I'll probably start with about 2400 watts of panels until I can get around to bringing the other 7600 Watts of panels online

Then I'll eventually add another inverter or two

Venus the fire up will be about 15 kilowatt hours for 39 phosphate and then once that system's up and running safely I can have the next 15 kilowatt hours (all this equipment I have just sitting around right now)

 

[Steve_S]

Your inverter is only giving you 1x 120V circuit, so you can only test 1 LEG not both legs ! 240V requires 2x 120V in opposite phases !
I run on 120V only and use standard Square-D Boxes, which are designed to be 120/240 and without a Mains Breaker ! If you have a Main Input Breaker, that only handles 240V Split Phase, you cannot change that to 120V only.

An A-Typical installation from such an Inverter (Non-AIO) is simple.
[interverter (3000W LF)] -->>[Small Breaker box with 1x30A/40A Breaker]--->> AC Distribution Panel.
{HF= 2x, LF=3x surge}--------{Acts as a Main Breaker replacement}-----{Standard "Sub-Panel" without Mains Breaker}

Inverters like the AIMS have a "Jumper Wire" for Neutral Bonding, this is to allow them for use in vehicles vs fixed land use. When installing into a system with a Ground this needs to be unplugged (Check manual for that model). That allows the single bonded earth ground from your grounding rod to handle everything attached. That even will allow the ground to the Generator through the inverter. You can ONLY HAVE 1 GROUND ! and that should be onto your AC Panel.

This is how I wired my sub-panel with a Bridge wire linking the two sides together for 120V use.

 

[ericfx1984]

Your inverter is only giving you 1x 120V circuit, so you can only test 1 LEG not both legs ! 240V requires 2x 120V in opposite phases !
I run on 120V only and use standard Square-D Boxes, which are designed to be 120/240 and without a Mains Breaker ! If you have a Main Input Breaker, that only handles 240V Split Phase, you cannot change that to 120V only.

An A-Typical installation from such an Inverter (Non-AIO) is simple.
[interverter (3000W LF)] -->>[Small Breaker box with 1x30A/40A Breaker]--->> AC Distribution Panel.
{HF= 2x, LF=3x surge}--------{Acts as a Main Breaker replacement}-----{Standard "Sub-Panel" without Mains Breaker}

Inverters like the AIMS have a "Jumper Wire" for Neutral Bonding, this is to allow them for use in vehicles vs fixed land use. When installing into a system with a Ground this needs to be unplugged (Check manual for that model). That allows the single bonded earth ground from your grounding rod to handle everything attached. That even will allow the ground to the Generator through the inverter. You can ONLY HAVE 1 GROUND ! and that should be onto your AC Panel.

This is how I wired my sub-panel with a Bridge wire linking the two sides together for 120V use.

I am well aware that my Aims is only 120v... But currently the house only has 120v circuits... There are NO 240v circuits to test (at least not yet)

 

[Steve_S]

You said you were trying to test the 240VAC side but with only a 120V leg. Maybe I can't read this early in the morning. Maybe I didn't understand... Good Luck, hope you sort it.

 

[GXMnow]

The neutral and the ground are probably bonded inside of the Aimes inverter, ahead of their GFCI outlet. When you then connect the neutral and ground to the panels that is also bonding the neutral to the ground it is causing some current to flow in the ground wire. It only takes about 20 milliamps of current in the ground wire to cause a GFCI to trip.

The proper fix is to ensure there is only one point where the ground and neutral are bonded together. Not connecting the inverter ground may sort of work, but now you could have a voltage potential on the case of the Aimes inverter. If it becomes high enough, touching the inverter case may give you a small shock, or hopefully trip the GFCI to protect you.

For a permanent installation, you have two options.

The first option (and the correct one if you will use the inverter input as a shore power connection) would be to remove the ground bond in the breaker panel. In most panels, the neutral bar probably has a single screw that extends into the case of the panel to provide the ground bond. The rest of the mounting screws on the neutral bar should be into an insulating plastic mount. If this is an older main panel, it might only have a single combined ground/neutral bar. In that case, you would need to add an insulated neutral bar. Then all of the neutral (white in the USA) wires would need to be moved to the new bar. But any ground wires (bare or green in the USA) should stay on the grounded bar.

The other option (if the system will never be used on grid) would be to look if there is instructions for lifting the internal neutral/ground bond inside the Aimes inverter. There is likely a single wire near the output terminal block where the neutral is connected to the chassis ground. It is probably even labeled as the ground lift. I found this Aimes manual online.

https://www.aimscorp.net/wp-content/uploads/2022/05/3k-bypass-manual-08302022.pdf

On the 24th page of the PDF, it explains how to remove the automatic neutral/ground bond. Your model may be different, so check your manual or search your model number to be sure.

 

[ericfx1984]

The neutral and the ground are probably bonded inside of the Aimes inverter, ahead of their GFCI outlet. When you then connect the neutral and ground to the panels that is also bonding the neutral to the ground it is causing some current to flow in the ground wire. It only takes about 20 milliamps of current in the ground wire to cause a GFCI to trip.

The proper fix is to ensure there is only one point where the ground and neutral are bonded together. Not connecting the inverter ground may sort of work, but now you could have a voltage potential on the case of the Aimes inverter. If it becomes high enough, touching the inverter case may give you a small shock, or hopefully trip the GFCI to protect you.

For a permanent installation, you have two options.

The first option (and the correct one if you will use the inverter input as a shore power connection) would be to remove the ground bond in the breaker panel. In most panels, the neutral bar probably has a single screw that extends into the case of the panel to provide the ground bond. The rest of the mounting screws on the neutral bar should be into an insulating plastic mount. If this is an older main panel, it might only have a single combined ground/neutral bar. In that case, you would need to add an insulated neutral bar. Then all of the neutral (white in the USA) wires would need to be moved to the new bar. But any ground wires (bare or green in the USA) should stay on the grounded bar.

The other option (if the system will never be used on grid) would be to look if there is instructions for lifting the internal neutral/ground bond inside the Aimes inverter. There is likely a single wire near the output terminal block where the neutral is connected to the chassis ground. It is probably even labeled as the ground lift. I found this Aimes manual online.

https://www.aimscorp.net/wp-content/uploads/2022/05/3k-bypass-manual-08302022.pdf

On the 24th page of the PDF, it explains how to remove the automatic neutral/ground bond. Your model may be different, so check your manual or search your model number to be sure.

It was a temporary thing anyway... Just a real quick test to make sure that the circuits in the house were functional... I've already got it sorted out and everything is working. Obviously everything will need to be correctly set up when I install the big inverter with the 16s lifepo4 battery bank