Hi All, I built power bank in my basement to act as sump pump back and to power my internet equipment since I work at home. I have Giandel 2000w inverter right now connected to 200ah lifepo4 (will add another soon). My question is do I need to ground my inverter and where is best place. This is in my basement with no easy way to run wire outside into ground? can I ground it to my homes conduit pipes? or water pipes?
Inverter grounding
- Thread starter Raf1919
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I'm guessing original to the house 1989. When you say panel, its the circuit breaker box in the basement right? If so thats doable for me its only maybe 8ft from where I'll have my battery pack.
LakeHouse
Solar Enthusiast
Both of those are things that could happen.
You mention it’s a backup for your sump. How is it tied into the permanent system? If that already has a ground wire and you tie into it, your inverter should be grounded.
ChillnGrill
Solar Enthusiast
When i built my system my lights would flicker like no tomorrow before I grounded the panel. As soon as I grounded my sub panel all work like it should.
I have transfer switch so if power goes out then my sump would run off the inverter. Its only thing plugged in.
Hedges
I See Electromagnetic Fields!
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GFIC outlet is also a good idea.
"Belt and suspenders"
(this idea is now dear to my heart; don't ask why!)
I often ground things with an extension cord to house outlet.
But best practice is where nothing can be powered up unless ground is provided. That comes for free with a 3-prong plug in grounded source, is more difficult to achieve with a portable inverter.
"Belt and suspenders"
(this idea is now dear to my heart; don't ask why!)
I often ground things with an extension cord to house outlet.
But best practice is where nothing can be powered up unless ground is provided. That comes for free with a 3-prong plug in grounded source, is more difficult to achieve with a portable inverter.
LakeHouse
Solar Enthusiast
Does the cable that runs into the transfer switch from your main panel have three conductors or two?
3 conductors from transfer switch on all 3 plugs. to AC, to Inverter, to Load. My pump itself is 3 prong but it plugs into float switch which is only 2 prong.
LakeHouse
Solar Enthusiast
If all three wires on each of the three cables are properly connected, your inverter should already be grounded.
You can test this by measuring the resistance between the ground lug on your inverter (assuming there is one, any bare metal body piece if there isn't) and something you know is grounded, like your electrical panel, which you noted isn't very far away. The resistance should be low; a few Ohms at most, likely much lower.
You can test this by measuring the resistance between the ground lug on your inverter (assuming there is one, any bare metal body piece if there isn't) and something you know is grounded, like your electrical panel, which you noted isn't very far away. The resistance should be low; a few Ohms at most, likely much lower.
Great will test it this weekend. Thanks alot everyone.
The only reason to ground a high frequency inverter that isn't connected to the main electrical system is to try to limit the voltage difference between components imposed by lightning. And then it would have to be a big wire jumped between all the components and the ground at the main electrical service. But grounding for short circuit protection is not going to work with most HF inverters because none of the AC output conductors are referenced to ground anyway.
Not likely that grounding had anything to do with that. Grounding doesn't have anything to do with the normal function of an electrical system. You probably accidentally cured the other problem while working on the ground.
A GFCI is useless on a system whose neutral isn't bonded to ground.
Zapper77
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I understood that a GFCI can function with out a ground. In fact NEC allows replacing an ungrounded 2 prong outlet with a GFCI.
"Section 406.4 (D) (2) provides options to replace the old two-prong receptacle without adding an equipment grounding conductor. One of the methods permitted in 406.4 (D) (2) is to replace a non-grounding type receptacle with a GFCI type receptacle. When doing this, the 2014 NEC required the “receptacle” to be marked “no equipment ground”."
Hedges
I See Electromagnetic Fields!
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I think you're both correct. If AC is floating, you can touch it without getting a shock, no current, so GFCI wouldn't trip.
If it developed a fault to ground somewhere, you'd never know. Then you could get a shock from it an GFCI would trip.
So I would ground it and use GFCI.
Older house wiring may not have the ground wire, but neutral is bonded to ground and line is a shock hazard. GFCI works in this case.
Some of those cheap inverters can't have neutral bonded to ground, or rather if you do, battery would get half the AC voltage on it.
Maybe there is a way to use them safely, but I'd rather have one that puts out true single or split phase, ground it, and use GFCI for circuits where appropriate.
If it developed a fault to ground somewhere, you'd never know. Then you could get a shock from it an GFCI would trip.
So I would ground it and use GFCI.
Older house wiring may not have the ground wire, but neutral is bonded to ground and line is a shock hazard. GFCI works in this case.
Some of those cheap inverters can't have neutral bonded to ground, or rather if you do, battery would get half the AC voltage on it.
Maybe there is a way to use them safely, but I'd rather have one that puts out true single or split phase, ground it, and use GFCI for circuits where appropriate.
Yes, you don't need a ground WIRE, but you do need a grounded circuit. The NEC is talking about a system that has a neutral grounded at the main service, regardless of whether a ground wire exists in the branch circuit wiring. The grounded point at the service is why the GFCI is able to function with no ground wire. This inverter setup doesn't have a grounded neutral, so a GFCI is just an expensive receptacle with some cool buttons on it.
Hedges
I See Electromagnetic Fields!
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Determine if the inverter allows neutral to be grounded.
Use DMM to check voltages L-N, L-G, N-G
If it makes 120Vrms L-N and each of those are 60Vrms to ground, it is either floating or symmetric, split-phase 60/120V.
Connect a light bulb between N and G. if light bulb illuminates dimly, you can't bond neutral. If voltage N-G drops to zero, it can be bonded.
But check battery(+) to G and (-) to G, both AC and DC. If it now has 60Vrms on the battery, you may not want to bond it.
If battery voltages are acceptable, don't have AC riding on top, then bond N to G at the inverter, ground G, use a GFCI.
If the inverter isn't compatible with bonding of neutral, at least ground inverter chassis and ground wire to sump pump. The AC voltages present are only 60 Vrms which is less hazardous than 120 Vrms, but still a problem if you're standing in water. I'm not going to recommend use of such an inverter for wet applications (nerves and more still frazzled from my recent encounter, fortunately bone dry), but it is your life. Don't expose anyone else to such a setup.
I have suggested isolation transformers to derive a neutral that can be bonded, but many transformers are nasty loads for inverters. It can be done; I would try to use two 240V windings as 120V primary and 120V secondary. I've measured that and it works better.
diysolarforum.com
Use DMM to check voltages L-N, L-G, N-G
If it makes 120Vrms L-N and each of those are 60Vrms to ground, it is either floating or symmetric, split-phase 60/120V.
Connect a light bulb between N and G. if light bulb illuminates dimly, you can't bond neutral. If voltage N-G drops to zero, it can be bonded.
But check battery(+) to G and (-) to G, both AC and DC. If it now has 60Vrms on the battery, you may not want to bond it.
If battery voltages are acceptable, don't have AC riding on top, then bond N to G at the inverter, ground G, use a GFCI.
If the inverter isn't compatible with bonding of neutral, at least ground inverter chassis and ground wire to sump pump. The AC voltages present are only 60 Vrms which is less hazardous than 120 Vrms, but still a problem if you're standing in water. I'm not going to recommend use of such an inverter for wet applications (nerves and more still frazzled from my recent encounter, fortunately bone dry), but it is your life. Don't expose anyone else to such a setup.
I have suggested isolation transformers to derive a neutral that can be bonded, but many transformers are nasty loads for inverters. It can be done; I would try to use two 240V windings as 120V primary and 120V secondary. I've measured that and it works better.
⚡Shock⚡ through the heart,
And you're to blame, You give solar a bad name! Meant to be safer than a cheater cord, power cord with shrouded banana plugs + Similar wire and banana connected to equipment under test. Now it's easy to stack banana plugs and plug in HV scope probe. It's just as easy to mix up Line and...
diysolarforum.com
That's not how I'd determine it. I'd follow NEC. The inverter needs a neutral ground bond period as it's the only source and is not grid tied to ground.. Does it need an additional "earth ground" - yes would be my answer also.
Hedges
I See Electromagnetic Fields!
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However, some 120V inverters are incompatible with neutral-ground bonding. They are basically 60V/120V split-phase.
So you can't do what you want per NEC.
You might be able to, but then a 12V battery would likely have its terminals at 0VDC + 60Vrms & 12VDC + 60Vrms.
I wouldn't recommend that. You don't want battery and any other DC components carrying hazardous voltages.
Best advice would be to use an inverter that is UL listed and connect in a safe and compliant manner. And use a GFCI.
I'm dealing with something similar right now, trying to find GFCI to use on 208V ... 277V from a UPS. I'm not clear yet on how its output is referenced to ground, have some indication it is neither neutral bonded nor balanced. Also not entirely isolated.
So you can't do what you want per NEC.
You might be able to, but then a 12V battery would likely have its terminals at 0VDC + 60Vrms & 12VDC + 60Vrms.
I wouldn't recommend that. You don't want battery and any other DC components carrying hazardous voltages.
Best advice would be to use an inverter that is UL listed and connect in a safe and compliant manner. And use a GFCI.
I'm dealing with something similar right now, trying to find GFCI to use on 208V ... 277V from a UPS. I'm not clear yet on how its output is referenced to ground, have some indication it is neither neutral bonded nor balanced. Also not entirely isolated.
