7.2KW ProPower for Off-Grid Cabin

[OT66]

It seems like the work was done by "some electrician". They may have done the bonding in the inverter as in my own opinion the way it is done in your panel it is wrong. So even if you unplug the groung in your panel you may achieve nothing. What I would do if it was my situation is to unplug the ground coming from the L14-30 going to the inverter. At least if this work you would know the 7.2KW can work with your system. At the end I would put the ground back to the inverter.

After bring a multimeter and take some measurement in your panel.

1- Measure between the ground bar and the neutral bar, you should have 0 ohm
2- Unplug the ground between the ground rod and your neutral bus, if you still have 0 ohm then your electrical system is bonded somewhere else.
3- If at step 2 you still have 0 ohm, then I think you should move the ground rod to the ground bar but don't connect the ground to the neutral bar as a system should be bonded at one location.
4-If at step 2 you don't have 0 ohm, then I think you should move the ground rod to the ground bar then run a wire from the ground to the neutral bar.

These are the steps that I would do if I was in your situation. Again I'm not an electrician and I can't take any of the responsibilities. I would like the comments from @Gros Ventre and @Hullguy as they seems to be a lot more knowledgeable about different codes and regulations

Removed ground wire from the the L14-30 plug and can confirm the cabin batteries are charging and cabin AC power running from ProPower.

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[Gros Ventre]

There

Your panel is neutral bonded, but your grounding isn't done to code. Your generator and truck are also neutral bonded. The generator's lack of GFCI means you're double bonded when using it (and it works). Your inverter requires neutral bond in the panel.

99% of people back-feeding their home (that have utility w/ manual gen failover) have double neutral bonded systems without issue. The issue arises when you introduce the GFCI as utility. Your situation is more unique than most due to you NOT having a permanent utility.

Code is written in the blood of lives lost due to improper installation causing fire / electrocution. For your system to work you'd I'd suggest floating the ground inbound from the truck at a separate junction box like the scribble diagram suggests....

Speaking of improper box connection, replace the blues with whites or wrap white tape around them. Neutrals should be marked with double white bands.

There is a problem with opening the ground wire between the truck and the house. Specifically it doesn't comply with the NEC. That does allow the truck generator to operate, but a voltage difference can build up between the two ground wires.

 

[OT66]

There
There is a problem with opening the ground wire between the truck and the house. Specifically it doesn't comply with the NEC. That does allow the truck generator to operate, but a voltage difference can build up between the two ground wires.

Now that I’ve confirmed I can at least get the truck to work with the system, what would happen if I hook the ground back to the plug and remove the ground from my panel at the neutral bus? The bond will be at the truck. When I’m not using the truck and running off of batteries/solar do I need a neutral bond in the panel?

 

[HammaMan]

There
There is a problem with opening the ground wire between the truck and the house. Specifically it doesn't comply with the NEC. That does allow the truck generator to operate, but a voltage difference can build up between the two ground wires.

True, it's not to NEC, the NEC doesn't have a solution for this, at all. To be NEC it would have to either be Truck, or solar inverter. There's no way to do this install to NEC with the inverter using excess charge to batts. It also won't allow voltage to build up on the grounds. Grounds serve as a backup to the neutral and for lightning protection. There's no possibility here for any current to show up on the grounds as I've illustrated. It takes 100% the spirit of the NEC from a safety perspective eliminating touch voltage danger.

 

[HammaMan]

Now that I’ve confirmed I can at least get the truck to work with the system, what would happen if I hook the ground back to the plug and remove the ground from my panel at the neutral bus? The bond will be at the truck. When I’m not using the truck and running off of batteries/solar do I need a neutral bond in the panel?

When the truck or generator isn't in use, your system is no longer neutral bonded. Neutral bonding to ground prevents 'touch' voltage deltas if a neutral comes loose.

You need to redo your panel to even make the possibility of removing the neutral bond in the panel. I'd first wire your panel as if the grounds and neutrals are isolated. BUT, and this is a big one, there's a high probability that if you do un-bond the panel it still won't work with the truck's GFI.

What I've suggested is safe, keeps ground protection in-place, and allows you to use the truck as a power source for the inverter that it can also 'scrape' the delta of the loads and charge the battery.

 

[OT66]

If that’s the case would I be better to unbond my panel and hook up the ground wire to my plug?

 

[Gros Ventre]

Now that I’ve confirmed I can at least get the truck to work with the system, what would happen if I hook the ground back to the plug and remove the ground from my panel at the neutral bus? The bond will be at the truck. When I’m not using the truck and running off of batteries/solar do I need a neutral bond in the panel?

If you can open the neutral-ground bond inside your house that could work. Essentially that is what a transfer switch does. But ensure you open the connection between the neutral and the ground inside your house and not just opening the ground wire inside the house. Depending on the panel you have, many panels come with a green neutral-ground bonding screw in the panel. You could remove that screw effectively doing the above. However look carefully: Some electric service providers require the neutral-ground bond to be made in other places like the service meter box outsdie the house. Since this is an "islanded house" without electrical service, removing that bonding screw may be just the ticket. Just don't forget to reinstall it when disconnecting from your truck.

 

[Gros Ventre]

True, it's not to NEC, the NEC doesn't have a solution for this, at all. To be NEC it would have to either be Truck, or solar inverter. There's no way to do this install to NEC with the inverter using excess charge to batts. It also won't allow voltage to build up on the grounds. Grounds serve as a backup to the neutral and for lightning protection. There's no possibility here for any current to show up on the grounds as I've illustrated. It takes 100% the spirit of the NEC from a safety perspective eliminating touch voltage danger.

Disagree.

 

[HammaMan]

Disagree.

You're free to. Go demand your utility feed you a ground to keep that bare neutral exposed on the outside of your home that also serves as the messenger for elevating L1 and L2 .... for whatever reason you're wanting the utility to provide you a ground.

When the NEC doesn't provide a solution you must look at the variables of the system to make it safe. utilities don't provide grounds and the neutral is exposed --- it's also screwed into the side of buildings and is the lower wire on utility poles (above the telco cables that is).

The truck is acting as utility in this instance, just like a generator. Utility doesn't provide ground.

 

[Paul Neubauer]

I don't understand why people spend this kind of money on a truck with the idea of using it as a power source instead of just buying a dedicated generator to use as needed. If you have to leave, all the stuff that was running off the trucks power is now disconnected instead of just filling the tank on a generator and keeping things going like a refrigerator and chest freezer.

 

[HammaMan]

I don't understand why people spend this kind of money on a truck with the idea of using it as a power source instead of just buying a dedicated generator to use as needed. If you have to leave, all the stuff that was running off the trucks power is now disconnected instead of just filling the tank on a generator and keeping things going like a refrigerator and chest freezer.

Because they don't typically need power where they're not (and the truck is where they're located as it's the transportation), they bought the truck for this feature, and it's the most efficient generator on the market....

The truck can produce 7kWh per gallon of gas used at max load. That's cheaper than some EU countries are now paying for power. Divide the cost of a gallon of gas by 7 and you've got your kWh cost. Gas here right now is $3/gal making the truck's cost per kWh 42.8 cents / kWh. Why spend $4k on a generator of similar specs just to have a 120# piece of equipment to lug around or have stolen.

 

[HammaMan]

I've got the remaining parts arriving this week to tap the HV bus of the truck and the goal is to get it to generate 20kWh of emergency power. Why spend this kind of money on a tool and not get the most out of it???

 

[OT66]

UPDATE… I reconnected the ground at the plug and removed the ground wire from the neutral bus in the panel. The system is working. When the truth is on it works which I expected it too and it also works with the truck off, running on batteries. Is there a safety concern with this? From what I can tell there’s no neutral/ground bond when I’m running off the batteries. My magnum inverter doesn’t bond from what I read so … ??

 

[Yves]

Would be happy to, but when the RV is on shore power (30Amp RV cable), it is grounded in the shore power panel, and the grounding rod that it is wired to. Right?

Correct.

 

[Snakebitten]

I don't understand why people spend this kind of money on a truck with the idea of using it as a power source instead of just buying a dedicated generator to use as needed. If you have to leave, all the stuff that was running off the trucks power is now disconnected instead of just filling the tank on a generator and keeping things going like a refrigerator and chest freezer.

I've been fulltiming in RV's for about 7 years. Admittedly I have been spending most of my time at my home base in coastal Texas because of my youngest grandchildren actually like me, for now. And yes, other than weather related power outages, the Powerboost isn't used nearly as much as when I'm galavantin around chasing sunrises and sunsets without an itenerary. The Powerboost is like a gift too good to be true. I no longer have to heft a 150lb Yamaha 3000 inverter into the bed of a truck. (that's empty of fuel. Closer to 175lbs with fuel) No longer have to tote gas cans. And the Powerboost is quieter, as well as fuel efficient.

It's an AMAZING grid on wheels!

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