140 volts at AC outlets

[PictureMeFree]

Hi all,

I am installing a Giandel 24V 2000 watt inverter into my camper van, and I am attempting to install a gfci circuit. The problem is that I’m getting 140 volts at the 2 outlets (gfci is first outlet in the circuit and feeds a 2nd non gfci outlet).

The inverter is supplying power to a circuit breaker box, and the multimeter reading coming out of the inverter outlets, at the hot and neutral busses in the box, and between the circuit breaker hot screw and box’s neutral- all read a perfect 120v. So, the issue is occurring between the circuit breaker and the outlets.

Does anyone know what could be causing this? I have ensured all connections are very tight and secure.

Also worth noting- the neutral and ground wires are bonded to one bus in the breaker box. Giandel told me there is no neutral/ ground bond inside the inverter and that I would need to bond neutral and ground in order for the gfci to function properly. I suspect something here is causing the issue, but again, the voltage reads 120 at all points inside the breaker box. It’s only high at the outlet terminals.

Thanks in advance for your experience and advice.

 

[GLC]

Try plugging in a light or something in that receptacle and then read what the voltage is then at the receptacle. I connected my neutral and my ground out of the inverter to the breaker box also, I am having no issues.

 

[PictureMeFree]

Try plugging in a light or something in that receptacle and then read what the voltage is then at the receptacle. I connected my neutral and my ground out of the inverter to the breaker box also, I am having no issues.

Thank you for your quick reply! Did you happen to run both the ground and neutral wires from your inverter and outlet circuits to the same bus bar in the breaker box?

Or, did you keep the neutral and ground busses separate but only use the bonding screw on the neutral bar?

I will try the outlet with something cheap plugged in and test voltage then. I just don’t want to charge my laptop or use my cooking devices at 140v…

 

[GLC]

Yes I did this, neutral and ground busses separate but only use the bonding screw on the neutral bar.

 

[PictureMeFree]

Yes I did this, neutral and ground busses separate but only use the bonding screw on the neutral bar.

I connected them all to one bar, thinking “bonding”… I picked up an additional bar and am going to separate neutrals from grounds, except for the one bonding screw, and I believe that will fix it. I’ll report back if it doesn’t…

 

[MrNatural22]

Don’t know if this is relevant but in my trailer I kept neutral and grounds separate in my breaker box. I run my inverter to a separate power strip and haven’t used the ground lug on the inverter.

 

[PictureMeFree]

So, I installed a ground bar terminal, and I separated neutrals from grounds inside the breaker box. The neutral bar has a bonding screw that I screwed all the way in. Everything in the box reads a perfect 120, but the two outlets are reading between 140 and 150 volts ?. How is this happening? How is the voltage rising 20-30 volts from the breaker to the gfci outlet? The hot screw on the circuit breaker reads 120 to the neutral and ground bars inside the box when it’s flipped on. The next stop is the gfci, where the voltage jumps.

I am thoroughly perplexed now.

 

[GLC]

Hmmm, still something goofy going on. Have you tried to plug something in and then check the voltage? Still is sounding like a ground issue somewhere. But when something is plugged in and makes a circuit does it clean up to 120?

 

[PictureMeFree]

Hmmm, still something goofy going on. Have you tried to plug something in and then check the voltage? Still is sounding like a ground issue somewhere. But when something is plugged in and makes a circuit does it clean up to 120?

I am hesitant to try it for not wanting to destroy whatever I plug in. The inverter outlets, and all power inside the box read a perfect 120, so I trust there is a significant increase happening at the outlets… if I’m missing something in my rationale, please let me know. I just don’t really want to sacrifice any of my electronics when it seems sure that the voltage reading is accurate…

 

[PictureMeFree]

The inverter is grounded to the chassis via the grounding screw, if that makes any difference…. Just trying to think of what the heck could be causing the voltage raise at the gfci and 2nd outlet, but not before them….

 

[A.Justice]

Try a multimeter with a low impedance mode, it will say something like LoZ on the selector knob.

Sometimes I get odd voltage readings when there's other wires nearby, it can be a "ghost" voltage. Worth a shot at least...

 

[PictureMeFree]

Just went to test the outlets with a load attached, and they are now magically at 120 V before I connected the load! Wtf?! I changed nothing, and now they are reading a perfect 120. If my wife hadn’t witnessed me test the inverter and box connections at 120 and then move to reading 140-150 at the outlets, like 10x in a row, I’d think I was going crazy. If anyone knows why this happened, I’d love to learn.

 

[GLC]

As A Justice noted above there was some "ghost voltage" registering. Normally when you pull energy off that line it will straighten out. That is why I was trying to get you to plug something in. I am guessing that it is something in the grounding setup that was causing that reading. Probably if that outlet was not a GFI then it would be reading what it should be. I am sure that there may be a brain-e-ack that could explain it scientifically but the main thing is that it has been addressed.

 

[A.Justice]

If anyone knows why this happened, I’d love to learn.

When a hot wire and a not hot wire (or, less often, two hots) are near each other for a distance, the hot can induce a voltage on the other wire. It's JUST a voltage, and doesn't normally have current behind it.

I'm making a bit of an educated guess here, but what I think happened is that your hot was near your neutral and / or ground wire, and induced ~20v over the neutral. 120v on hot + 20v on neutral, = 140v.

Ghost voltages pretty much always disappear when you attach a load.

 

[PictureMeFree]

As A Justice noted above there was some "ghost voltage" registering. Normally when you pull energy off that line it will straighten out. That is why I was trying to get you to plug something in. I am guessing that it is something in the grounding setup that was causing that reading. Probably if that outlet was not a GFI then it would be reading what it should be. I am sure that there may be a brain-e-ack that could explain it scientifically but the main thing is that it has been addressed.

Agree on all counts, and I really appreciate you taking the time to offer solutions to a stranger. This forum is awesome. Thanks again to you and A.Justice