That was a very well written, focused and informative comment…lot of good info in one tightly wound package..thx…
J.
Live Ground Shocked 5 Year Old
- Thread starter Joshua787
- Start date
J.
I’m making assumptions and they can be dangerous, especially remotely.
You have two Growatts, single phase in parallel to Growatt auto transformer for split phase. Correct me if I’m wrong but the neutral and ground must come together(bonded) one place and that’s after the split phase transformer in the main breaker box. All inverters, breaker boxes and auto transformer chassis must be grounded. Ground at transformer appears missing. Neutrals from inverters should not have any bond to ground before the transformer. If you tied the inverter neutrals together on a buss at the inverter breaker box, is there a bonding screw in place by accident? Be aware if that’s the 5000 watt version auto transformer it may be on the small side and won’t tolerate much phase imbalance. Again have a qualified electrician look at these points.
You have two Growatts, single phase in parallel to Growatt auto transformer for split phase. Correct me if I’m wrong but the neutral and ground must come together(bonded) one place and that’s after the split phase transformer in the main breaker box. All inverters, breaker boxes and auto transformer chassis must be grounded. Ground at transformer appears missing. Neutrals from inverters should not have any bond to ground before the transformer. If you tied the inverter neutrals together on a buss at the inverter breaker box, is there a bonding screw in place by accident? Be aware if that’s the 5000 watt version auto transformer it may be on the small side and won’t tolerate much phase imbalance. Again have a qualified electrician look at these points.
Vigo
Solar Addict
I admit it's been so long that i've already forgotten but what is it about the ground screw needing to be removed in SPF5000ES's? I did mine, but ive already forgotten if this was changed along the way and no longer needs doing on newer versions?
Connect 60w light bulb to same spot where you measured 120V. If it lights up then you have a problem. If it does not and voltage drops to near zero then ground the container to your ground rod. It would help us figure out your problem if you drew a circuit diagram of how you have everything hooked up.
Where is neutral to ground bond? When you say autoformer , it's job is to nudge the neutral around so it stays centered between the two 120v hots. If you had only a small load on one leg and a heavy load on the other 120v leg (unblanced), then the autoformer would be moving the neutral around (voltage wise, please bear with my analogy).
Rule is ground and neutral bonded at ONLY one point, usually the first load center in the structure. This gets aggravating when off grid because the "ground neutral bond" needs change when you run on grid vs on a generator.
The other rule is all metal boxes are GROUNDED. Remember , ground should never be a current carrying conductor. That's the neutral's job.
Years ago I was in a communications trailer and it was plugged into a plug on a lamp post. Well, turns out someone had climbed the pole and tapped off one leg of the nightlight for the plug we were using. This meant the trailer chassis was floating at 120v just as you've described. My solution was to ground rod the trailer for our event. The correct solution was to provide ground neutral bond at that plug (it was the first point of service).
And finally.... cute kid. Mine used to be that little.
Hey I just read your oringial post again... those growatt inverters are not for the US market. They have a ground neutral bond on one end, not correct for split phase. I think there's a screw in the chassis that needs to be removed. Check will prowse youtube for that screw. It was all the rage about 2 years ago.....
More info: If your autoformer were to fail or pop it's breaker, you would apply 240v to all your 120v appliances... is it worth it? A wife flipping the wrong breaker for example could cause the microwave and fridge to get fried.... is it worth it?
Hedges
I See Electromagnetic Fields!
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There can be ways to make the auto-transformer work and not fry things, at least if not also connecting to grid.
It involves shutting off all loads if auto-transformer gets overloaded. Victron auto-transformer takes care of that. Some Growatt configurations may also. Can also be done with small 120/240V loads panel and large 240V only panel.
But done wrong, could fry 120V loads, brown-out (and fry) 240V loads, overheat transformer, etc.
Better to get US equipment meant for split phase, but it may be possible to safely use the 240V European models.
(There are US products which also rely on external auto-transformer.)
It involves shutting off all loads if auto-transformer gets overloaded. Victron auto-transformer takes care of that. Some Growatt configurations may also. Can also be done with small 120/240V loads panel and large 240V only panel.
But done wrong, could fry 120V loads, brown-out (and fry) 240V loads, overheat transformer, etc.
Better to get US equipment meant for split phase, but it may be possible to safely use the 240V European models.
(There are US products which also rely on external auto-transformer.)
wpns
Solar Joules are catch and release
Is this because the generator has a N-G bond? Hence not true when the generator isn’t bonded? My Honda EU3000iS does not have a bond…
robby
Photon Vampire
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Normally I would not agree with this statement but Growatts, Autransformers and a metal shipping container plus a Child involved make this one kind of unique.
I AGREE: Get a professional electrician in and have him check this out. Either that or get your Wife and Daughter out of there while you work this problem.
finite
New Member
Im of the opinion that it is a completely resonable statement givin the circumstances, ive smacked an old lady who was about to touch a live buss bar. Id bet hed rather have hurt feelings and bruised ego than a dead wife/daughter
Joshua787
New Member
Thank you for the concern, much appreciated. I disconnected completely the outlet and wire that ran to the metal box screwed to the shipping container to limit the circuit to just the inverters, circuit breaker panels and transformer. This would allow me to trouble shoot within that specific space. Ive been reading up and the issue seems like its a ground/neutral bond from the inverters. Apparently there is a US version and a European version.
Joshua787
New Member
Where did you find instructions on how to do this? did removing that ground screw help your system?
Joshua787
New Member
Thank you for the concern, much appreciated. I disconnected completely the outlet and wire that ran to the metal box screwed to the shipping container to limit the circuit to just the inverters, circuit breaker panels and transformer. This would allow me to trouble shoot within that specific space. Ive been reading up and the issue seems like its a ground/neutral bond from the inverters. Apparently there is a US version and a European version.
Access to the shipping container has been revoked for both my wife and daughter till this issue is solved! Thank you everyone for the concerns.
Please…
Before you attempt ANY troubleshooting, get good lighting, and take detailed pictures of everything connected to the container, let us see the boxes, wires junctions everything.
We may see the issue right away, and save you a lot of headache.
hwy17
Anti-Solar Enthusiast
I think we could still use detailed wiring pics. There's all sorts of possibilities and people jump to conclusions especially about grounding and bonding.
Auto transformer looks hard wired into 120v loads panel (right panel). Flipping its breaker (left panel) would remove both L1 and L2 so no chance of 120V loads being unbalanced.
Big question for @Joshua787 is the ground rod connected to Growatt's ground and is there a neutral to ground bond at the breaker panel? My guess is the neutral to ground bonding screw is in place inside Growatt and no N-G bond in the panel. This will bias the neutral to 120Vac in relation to earth ground. So L2 is actually at earth potential, N is at 120V and L1 is at 240V. This is probably why you were measuring live voltage in the outlet with breaker turned off. Your neutral to ground had 120V.
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Mike 134
Solar Enthusiast
Just a quick follow-up to my advice I offered. I fed my family working as an electrician giving me enough knowledge to know I can't walk you through this online and be 100% certain of your family's safety.
To those posting help do you feed your family doing electrical work? or is this a hobby? The OP has a right to know just how much you really know.
hwy17
Anti-Solar Enthusiast
DIY is the name of the forum. Everyone here is tacitly accepting the risk of their own actions and understanding the nature of the advice received.
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Hedges
I See Electromagnetic Fields!
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Nope.
But how many electricians understand inverters? Or the nuances of auto-transformers?
Besides, I'm "experienced".
I agree it is best to have someone who understands these things to check it over and debug in person.
For many of us here, that would be ourselves. Even better to get a second opinion.
But how many electricians understand inverters? Or the nuances of auto-transformers?
Besides, I'm "experienced".
I agree it is best to have someone who understands these things to check it over and debug in person.
For many of us here, that would be ourselves. Even better to get a second opinion.
Hedges
I See Electromagnetic Fields!
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"grounding" the container will not stop it from being a shock hazard. Bonding and grounding could.
That's why we keep telling people they need a wire that bonds PV panel frames to inverter chassis. Not just a separate ground rod at the frames.
The two most likely issues with OP's system are
1) PV frames have AC capacitively coupled to them because inverter imposes AC on PV+/-
2) Inverter has one of its two 240V legs bonded to chassis, and auto-transformer center tap ("Neutral") has a path to earth (i.e. is "grounded"). As Antron describes.
Adding a separate ground for the container could mean two ~ 25 ohm connections to earth, with current running through them.
Ideally we would get to see a schematic of entire system.
That's why we keep telling people they need a wire that bonds PV panel frames to inverter chassis. Not just a separate ground rod at the frames.
The two most likely issues with OP's system are
1) PV frames have AC capacitively coupled to them because inverter imposes AC on PV+/-
2) Inverter has one of its two 240V legs bonded to chassis, and auto-transformer center tap ("Neutral") has a path to earth (i.e. is "grounded"). As Antron describes.
Adding a separate ground for the container could mean two ~ 25 ohm connections to earth, with current running through them.
Ideally we would get to see a schematic of entire system.
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robbob2112
Doing more research, mosty harmless
First, this is DIY.
Second, it is pretty arrogant of you to assume nobody here knows anything about this sort of problem.
Many here have practical experience and more than enough education to know what they are saying. I know I wouldn't give advice in here until the OP posts back pictures and a wiring diagram so I wouldn't give a wrong answer.
I can see your point that the OP should carefully consider the advice he is given before doing things. And be double careful about testing before letting his famliy near. But it doesn't take a certified master electrician to track down an issue like this.
Partimewages
Solar Addict
34 year licensed electrician. Let me be the first one to say I don't know it all.
I know an abundance of trade people. Most electricians don't understand low voltage high current circuits.
WE CAN ALL LEARN FROM EACH OTHER!
I know an abundance of trade people. Most electricians don't understand low voltage high current circuits.
WE CAN ALL LEARN FROM EACH OTHER!
timselectric
If I can do it, you can do it.
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Short answer.
Your system is not properly grounded.
You don't have a N/G bond.
Your system is not properly grounded.
You don't have a N/G bond.
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