electrical help please

eabyrd

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If the grey lines are denoting neutrals, they shouldn't be tied together(paralleled) anywhere in the images, beginning with the one above the word main in the upper left panel. The neutral buses shouldn't be bonded to the panels. Grounds, under normal conditions, shouldn't carry any current.
Phase conductors must be run adjacent to their neutral conductors.
(I probably have no idea what those images represent.)
You’re the first to suggest that. Everything I know about residential electric service says that neutral and ground are to be bonded in one and only one location in a system, generally this is at the main distribution panel / service entry. That is the bond shown in the main panel The neutral and ground bars in the subpanel are kept separate but tie back to their brothers in the main
 

FilterGuy

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If the grey lines are denoting neutrals, they shouldn't be tied together(paralleled) anywhere in the images, beginning with the one above the word main in the upper left panel. The neutral buses shouldn't be bonded to the panels. Grounds, under normal conditions, shouldn't carry any current.
Phase conductors must be run adjacent to their neutral conductors.
(I probably have no idea what those images represent.)
I agree, the 'as implemented' has big loops in the neutral circuit that should not be there. However, the line between the ground bus and neutral bus is, in NEC parlance, the Main Bonding Jumper and is appropriate. It is the neutral connection between the Grounding busbar in the Main panel and the Neutral Bus in the critical loads panel that is concerning (and I think should be removed).

1629146444877.png

However, I would not want to run the system without the inverter tied into the ground system.

It would be helpful to know more about the auto xfer switch. (Does it switch neutral or does it only switch the two hots?)
 

eabyrd

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I agree, the 'as implemented' has big loops in the neutral circuit that should not be there. However, the line between the ground bus and neutral bus is, in NEC parlance, the Main Bonding Jumper and is appropriate. It is the neutral connection between the Grounding busbar in the Main panel and the Neutral Bus in the critical loads panel that is concerning (and I think should be removed).

View attachment 60420

However, I would not want to run the system without the inverter tied into the ground system.

It would be helpful to know more about the auto xfer switch. (Does it switch neutral or does it only switch the two hots?)
It is the neutral connection between the Grounding busbar in the Main panel and the Neutral Bus in the critical loads panel that is concerning (and I think should be removed). Agreed. It makes me nervous too.
 

eabyrd

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I agree, the 'as implemented' has big loops in the neutral circuit that should not be there. However, the line between the ground bus and neutral bus is, in NEC parlance, the Main Bonding Jumper and is appropriate. It is the neutral connection between the Grounding busbar in the Main panel and the Neutral Bus in the critical loads panel that is concerning (and I think should be removed).

View attachment 60420

However, I would not want to run the system without the inverter tied into the ground system.

It would be helpful to know more about the auto xfer switch. (Does it switch neutral or does it only switch the two hots?)
I would not want to run the system without the inverter tied into the ground system.again agreed. I do not plan to
 

eabyrd

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I agree, the 'as implemented' has big loops in the neutral circuit that should not be there. However, the line between the ground bus and neutral bus is, in NEC parlance, the Main Bonding Jumper and is appropriate. It is the neutral connection between the Grounding busbar in the Main panel and the Neutral Bus in the critical loads panel that is concerning (and I think should be removed).

View attachment 60420

However, I would not want to run the system without the inverter tied into the ground system.

It would be helpful to know more about the auto xfer switch. (Does it switch neutral or does it only switch the two hots?)
It would be helpful to know more about the auto xfer switch. (Does it switch neutral or does it only switch the two hots?). The ATS switches both hot & neutral

bottom line is MPP solar needs to fix whatever is causing the unit to choke on the wiring shown in the first diagram. That layout is true to their manual
 
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eabyrd

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Eabryd, can you ground the inverters chassis back to the main panel?
Good thought, but I tried that as part of the diagnostics, and it creates the same problems for the device. Looking inside you can see that the input ground and output ground connect to each other and the chassis
 

Cheap 4-life

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Good thought, but I tried that as part of the diagnostics, and it creates the same problems for the device. Looking inside you can see that the input ground and output ground connect to each other and the chassis
Im not saying it would fix your issue. I’m saying then the inverters chassis would then be grounded. The inverters ground output still could remain disconnected
 

eabyrd

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Im not saying it would fix your issue. I’m saying then the inverters chassis would then be grounded. The inverters ground output still could remain disconnected
True, but no different than having an input or output ground since there is continuity betweebn them and both being tied to the chassis
 

eabyrd

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It would be helpful to know more about the auto xfer switch. (Does it switch neutral or does it only switch the two hots?). The ATS switches both hot & neutral

bottom line is MPP solar needs to fix whatever is causing the unit to choke on the wiring shown in the first diagram. That layout is true to their manual
I had an error in the post above which I've corrected. The ATS switches both hot and neutral.
 

FilterGuy

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Surge Guard 40100 - It's an 50-amp RV switch, UL listed for mobile, but not for residential service.
Nice!! Be aware though that with that transfer switch, when the inverter is fed from the panel it 'sees' the N-G bond of the panel. However, when the inverter is being fed by the generator, the input to the inverter does not 'see' the N-G bond.

BTW: Can you tell if the inverter input neutral is tied directly to the output neutral?
 

eabyrd

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Nice!! Be aware though that with that transfer switch, when the inverter is fed from the panel it 'sees' the N-G bond of the panel. However, when the inverter is being fed by the generator, the input to the inverter does not 'see' the N-G bond.

BTW: Can you tell if the inverter input neutral is tied directly to the output neutral?
Yeah, I realized that too. In this case switching neutral is actually unneeded and a bit of a bother. :) Its always something, isn't it.

Here's my current concept, I'm now just passing hots through the ATS to the inverter. Inverter then creates its own neutral (tested this and it does work that way) I also added a service path as you suggested (Reliance TCA 0606 thanks for that idea). but until MPP gets back with a solution to the grounding issue I'm only theorizing
 

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eabyrd

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BTW: Can you tell if the inverter input neutral is tied directly to the output neutral?
Another good question.
Utility connected, unit off - no continuity
Utility connected, unit on bypass mode - continuity
Utility not-connected, unit on battery mode - no continuity
Utility connected, unit on battery mode - no continuity

So my initial idea of passing neutral back through the unit to the main panel wouldn't have worked too well.

Thanks for asking these questions.

E
 

FilterGuy

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Another good question.
Utility connected, unit off - no continuity
Utility connected, unit on bypass mode - continuity
Utility not-connected, unit on battery mode - no continuity
Utility connected, unit on battery mode - no continuity

So my initial idea of passing neutral back through the unit to the main panel wouldn't have worked too well.

Thanks for asking these questions.

E
OK.... it sounds like the output Neutral on the inverter is separated from the input neutral. That is important for a couple reasons
1) You definitely want to remove that neutral between the two distribution panels.
2) The neutral for the existing Phase 1/2 critical loads should be connected to the critical loads panel, not the main panel.

1629223565355.png

After you make these changes, try hooking ground to the inverter again.
 

eabyrd

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OK.... it sounds like the output Neutral on the inverter is separated from the input neutral. That is important for a couple reasons
1) You definitely want to remove that neutral between the two distribution panels.
2) The neutral for the existing Phase 1/2 critical loads should be connected to the critical loads panel, not the main panel.

View attachment 60538

After you make these changes, try hooking ground to the inverter again.
What about leaving the neutral between the panels, but not passing neutral into the inverter, see my latest diagram. I'm trying to not have to pull 15 neutrals to go with the 15 hots. (OK 8 or 9 neutrals since I'll need to pull neutrals for the Arcfault circuits regardless)


Right now there is no connection between the subpanel and the main panel, and I've tried connecting input ground to the inverter. Even with the sub-panel completely isolated from the main, in fact even with the battery and the output terminals completely disconnected it starts to do its cycle thing as soon as I "turn it on". If the battery is connected it starts to cycle even when off (which I presume is because it wants to go into a charge cycle)
 

FilterGuy

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What about leaving the neutral between the panels, but not passing neutral into the inverter, see my latest diagram.
From what you describe, it sounds like the inverter wants to isolate the output Neutral from the input neutral when in inverter mode. That tells me you should *not* tie the neutral of the two panels together.

I'm trying to not have to pull 15 neutrals to go with the 15 hots. (OK 8 or 9 neutrals since I'll need to pull neutrals for the Arcfault circuits regardless)
Yup, a real pain in the butt!!!

Warning: The following may not be to code..... but it could make things easier.

Would it be possible to mount a 2nd isolated neutral bus bar in the main panel and run a single large Neutral to it from the critical Loads panel? Then your critical loads neutrals can tie to it.

 

FilterGuy

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Right now there is no connection between the subpanel and the main panel, and I've tried connecting input ground to the inverter. Even with the sub-panel completely isolated from the main, in fact even with the battery and the output terminals completely disconnected it starts to do its cycle thing as soon as I "turn it on". If the battery is connected it starts to cycle even when off (which I presume is because it wants to go into a charge cycle)
Can you return it?
 

eabyrd

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Can you return it?
Haven't yet asked. I spent a couple hours on the phone with MPP support out of Utah friday. He was going to get back to me after talking to Taiwan. He thought there was a firmware upgrade for the issue of the ground sense. I nudged him this morning on the issue. I bought it from SanTan solar, not directly from MPP, and I have asked about an RMA yet
 
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