120V on neutral

[davidgarrett]

While working in a customer's house, I discovered each neutral has 120V to ground in the panel when disconnected from the neutral bar. I opened a few receptacles and switches to discover the same 120V on the neutrals there also. This is a ML 100A panel located in a finished basement being fed by a MB 100A panel located outside next to the meter. There is also a ML 200A panel next to it being fed by a MB 200A panel outside also. Everything in the house seems to be working fine and no breakers are tripping. I spent about 4 hours trying to figure out the problem with no success. I asked the homeowner to call the POCO to eliminate the possibility of it being a problem with the incoming service. Does anyone have any experience with this and can offer some explanation as well as a solution?

Thanks in advance for your help!

 

[ptonsparky]

You are testing an open circuit. You will have 120 volts to ground. Turn the breaker(s) off and the voltage will disappear. Put the neutrals back on the bar.
What were you testing for when you made this discovery?

You may have lucked out and no multi wire branch circuits were in use. Then again maybe not. Prepare to open your wallet.

 

[texie]

While working in a customer's house, I discovered each neutral has 120V to ground in the panel when disconnected from the neutral bar. I opened a few receptacles and switches to discover the same 120V on the neutrals there also. This is a ML 100A panel located in a finished basement being fed by a MB 100A panel located outside next to the meter. There is also a ML 200A panel next to it being fed by a MB 200A panel outside also. Everything in the house seems to be working fine and no breakers are tripping. I spent about 4 hours trying to figure out the problem with no success. I asked the homeowner to call the POCO to eliminate the possibility of it being a problem with the incoming service. Does anyone have any experience with this and can offer some explanation as well as a solution?

Thanks in advance for your help!

There is no "solution". This is perfectly normal. All I can say is you better get up to speed on basic electrical theory before you do some serious damage to some expensive loads by disconnecting a neutral of live circuit. Maybe you just got lucky and none of the neutrals you lifted were part of a MWBC.

Now that I got the harsh words out of the way, seriously, it is imperative that you understand basic electrical theory or things like this can lead to some serious issues. With a little study you will quickly understand this.

 

[davidgarrett]

There is no "solution". This is perfectly normal. All I can say is you better get up to speed on basic electrical theory before you do some serious damage to some expensive loads by disconnecting a neutral of live circuit. Maybe you just got lucky and none of the neutrals you lifted were part of a MWBC.

Now that I got the harsh words out of the way, seriously, it is imperative that you understand basic electrical theory or things like this can lead to some serious issues. With a little study you will quickly understand this.

Okay, I understand now. But what I forgot to mention earlier was that I also have a black wire reading 0V to ground when connected to a breaker. When disconnected, it reads 120V to ground also. This is what threw me off, I have a 120V feeding back into a panel to me. Any idea how I can find out where?

 

[ActionDave]

Okay, I understand now. But what I forgot to mention earlier was that I also have a black wire reading 0V to ground when connected to a breaker. When disconnected, it reads 120V to ground also. This is what threw me off, I have a 120V feeding back into a panel to me. Any idea how I can find out where?

You can't have 0V to ground at the panel when the breaker is on and the wire is landed on the breaker. Where were you testing?

What was the problem you were chasing? What was the problem circuit powering?

 

[davidgarrett]

You can't have 0V to ground at the panel when the breaker is on and the wire is landed on the breaker. Where were you testing?

What was the problem you were chasing? What was the problem circuit powering?

But I did have 0V to ground at the panel with the breaker on. I took the wire loose, and had 120V to ground on the end of the wire as it comes into the panel.

The original problem I was chasing was a light not working. I measured 120V hot to ground at the light and the switch. I measured ~60V hot to neutral at the switch.

 

[GoldDigger]

You are saying that the hot to neutral and hot to ground differed by 60v?
That should tell you something!

Sent from my Droid Maxx

 

[ActionDave]

You are saying that the hot to neutral and hot to ground differed by 60v?
That should tell you something!

Sent from my Droid Maxx

Tell what? Tell me too.

davidgarrett it sounds like there is more than one problem to fix. I don't see how you can have zero volts unless you have a bad breaker or are missing a phase.

 

[Little Bill]

But I did have 0V to ground at the panel with the breaker on. I took the wire loose, and had 120V to ground on the end of the wire as it comes into the panel.

The original problem I was chasing was a light not working. I measured 120V hot to ground at the light and the switch. I measured ~60V hot to neutral at the switch.

Are you sure you even have a neutral at the switch?
That 60V reading sounds like phantom voltage or no neutral there.

Why did you measure hot to ground at the light and not hot to neutral?

 

[1793]

Maybe he got a reading from the load.

 

[GoldDigger]

Tell what? Tell me too.

Well, three possibilities stand out:
1. Neutral is not actually connected.
2. Ground (EGC) is not actually connected.
3. Ground is not connected (bonded) to neutral.
Bottom line is that without a known reverence point all of the voltage readings are suspect.

OP: And as ActionDave points out, you will get more meaningful readings in this case with a low impedance meter.

Sent from my Droid Maxx

 

[normbac]

While working in a customer's house, I discovered each neutral has 120V to ground in the panel when disconnected from the neutral bar. I opened a few receptacles and switches to discover the same 120V on the neutrals there also. This is a ML 100A panel located in a finished basement being fed by a MB 100A panel located outside next to the meter. There is also a ML 200A panel next to it being fed by a MB 200A panel outside also. Everything in the house seems to be working fine and no breakers are tripping. I spent about 4 hours trying to figure out the problem with no success. I asked the homeowner to call the POCO to eliminate the possibility of it being a problem with the incoming service. Does anyone have any experience with this and can offer some explanation as well as a solution?

Thanks in advance for your help!

Your post says you disconnected EACH neutral from the neutral bar which is why the replies warned you of possible dangers in doing so. Also everything in the house seems to be working fine?????

 

[ActionDave]

Well, three possibilities stand out:
1. Neutral is not actually connected.
2. Ground (EGC) is not actually connected.
3. Ground is not connected (bonded) to neutral.
Bottom line is that without a known reverence point all of the voltage readings are suspect.

OP: And as ActionDave points out, you will get more meaningful readings in this case with a low impedance meter.

Sent from my Droid Maxx

All true. A bad splice or connection some where on the circuit as another possibility. 60V may be significant, can't say for sure but 0V at the panel with the breaker on.... 120V when the wire is pulled off.. exactly what is going on.....? There is another shoe needing to be dropped before one can know what is wheat and what is chaff.

BTW I do have a low z function on my meter and use it when troubleshooting but I did not mention that. How did you know? What else is your Doid Maxx telling you about me?

 

[GoldDigger]

Not much except what you write. And I have no idea yet what kind of meter davidgarret is using.

 

[Sahib]

but 0V at the panel with the breaker on.... 120V when the wire is pulled off.. exactly what is going on.....?

Perhaps neutral is connected to the breaker instead of phase by mistake?

 

[mbrooke]

When touching the neutral bar did you get shocked? Did the phase reading zero volts shock?

GO to the main panel and test the voltages hot to hot, hot to neutral, then neutral to a known good ground then same with each phase to ground.



Sounds to me like either an open neutral or the poco forgot to ground down the neutral or a hot is grounded down instead of the neutral.

If its a sub panel the panel could be miss fed in that a hot is landed on the main neutral bar and the neutral on a breaker in the main panel or what ever is feeding it.



If this is just at the branch level open EGC or neutral sounds like the culprit.

 

[J.P.]

From my experience with odd problems you most likely have a neutral falling out of a wirenut somewhere. The weirder things are the more likely it is to be a loose neutral.

I am assuming that it is a service call to a building that was working fine until........... are there some new fixtures?

Do you know where the hot and it's neutral end up at from the panel?

If you have the hot turned off and your neutral is hot. You either don't have the right neutral or you are on a circuit with a shared neutral, either by accident or on purpose.

Follow your circuit, I would personally start at any new work.

Also in re-reading your post you say you have 0v to ground with the breaker on?
Are you testing this right at the panel?
On the breaker screw?
Does your neutral bar to ground bar ring through the bonding?
If so your breaker is bad.
If not your ground isn't bonded and also isn't doing much.
If your testing for power in a junction box and getting no power with the breaker on............find every box in the circuit if you have to.

 

[kwired]

Okay, I understand now. But what I forgot to mention earlier was that I also have a black wire reading 0V to ground when connected to a breaker. When disconnected, it reads 120V to ground also. This is what threw me off, I have a 120V feeding back into a panel to me. Any idea how I can find out where?

Did you check to see that you have full 240 volts from ungrounded to ungrounded on the supply? You could have lost an incoming ungrounded conductor based on what you are saying,