Wiring inverters to breaker box (off grid)

WYtreasure

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With small portable inverters you have to be careful with n/g bonding. Especially when the DC negative is grounded to the inverter shell. They tend to release their magic smoke.
Do we know that both inverters are "Negative" ground? Worst case could be a Positive Ground unit.
 

timselectric

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Whatever you end up doing. I would isolate the inverter case from ground. Using rubber feet. I have had inverters suffer their demise in the past.
 

12VoltInstalls

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Hmmmm. Funny, if I test my surge protector from the inverter now my tester reads no ground.
That’s typical. Check continuity between inverter case bare metal ground lug and 120V neutral directly to remove all doubt.

If it’s truly open then your main panel should have the only neutral-ground in the system.
 

timselectric

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I would check for continuing between inverter case and,
Ground
Neutral
Hot
Positive
Negative

Edit: both, while powered and not.
 

12VoltInstalls

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And what am I looking for exactly? I would like to solve my lack of ground issue.
You want to have zero ohms between a bare metal point on case and the Batt(-) and infinite ohms between batt(-) and both N and Line
The cheapo Amazon inverter had no ground lug.
You want to have zero ohms between a bare metal point on case and the Batt(-)
Check that. If none, throw cheapo inverter away or use some point of bare metal on case to run a separate wire back to batt(-) bus plus main panel ground in case of 120V fault imho
 
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Flip

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You want to have zero ohms between a bare metal point on case and the Batt(-) and infinite ohms between batt(-) and both N and Line

You want to have zero ohms between a bare metal point on case and the Batt(-)
Check that. If none, throw cheapo inverter away or use some point of bare metal on case to run a separate wire back to main panel imho
I'm not sure if this is related, but if my system shuts down (manually or bms senses under temp, etc), the bms sees the cheapo as a short circuit. I have to disconnect the positive lead, wait for the bms to turn the batteries back on, then reconnect the positive (sparks flying). I thought it was drawing too much current trying to restart at the same time as everything else, but maybe that's not the case.
 

12VoltInstalls

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bms sees the cheapo as a short circuit.
That might be when the capacitors charge?
The bms limit may be lower than the momentary surge at startup

I edited this you quoted because it left out a portion of the thought: “use some point of bare metal on case to run a separate wire back to main panel ground in case of 120V fault and another to batt(-) imho”
 

timselectric

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Won't the meter dislike the continuity test between HOT and Ground?
Sorry, don't do continuity on hot, while on. Check for voltage instead between hot and ground. Preferably, you won't have continuity between anything.
Only neutral and/or Ground to case continuity would be acceptable.
 

Flip

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That might be when the capacitors charge?
The bms limit may be lower than the momentary surge at startup

I edited this you quoted because it left out a portion of the thought: “use some point of bare metal on case to run a separate wire back to main panel ground in case of 120V fault and another to batt(-) imho”
I did pull a case screw and run a ground to the main ground bus since there was no ground lug. I didn't know the tech behind it, but seemed like the minimum thing to do.
 

timselectric

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That could be a problem. If the inverter is only designed for a floating ground.
 
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