# Voltage on GFCI ground with no ground wire



## CADPoint (Jul 5, 2007)

Divide and conquer is not the correct technic here.

If you said that the wiring is illegal from the get go why try to 
cure anything else?


> Branch circuit serving former garage finished (not to code) and being used as studio/office.


The only thing I'd do is rollback everything and Meggar everything!
This is going to be the only way to ID what's good and what's bad IMO!


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## mitch65 (Mar 26, 2015)

Junction box covered up in the ceiling or wall hiding bad splice(s) from you? Is N to ground good on the home run?


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## telsa (May 22, 2015)

Draw up a circuit diagram and begin your attack.

Goofy voltage readings -- like yours -- normally pan out as floating neutrals -- but there are other possibilities -- now that we're getting all of our trims from Red China.

I'd start from Line and head to Load... and re-build the few circuits up entirely. That can't take long with exposed runs in a garage.

You're PV array comments ... I can't follow them.

Who was on first?


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## DesertDawg (Jun 6, 2013)

*A little clarification...*

Sorry I took so long to get back. When I said the room wasn't to code, what I meant was that whoever wired it clearly didn't have it inspected so therefore it wasn't permitted and probably not done by a licensed electrician simply because there are not enough receptacles (6'-12') to satisfy code. They used 12/2 NM and approved junction boxes but pulled power from an old ungrounded circuit. In fact, most of the house is still wired with the old romex that has no ground and the panel is also ungrounded (and in a kitchen cabinet). I see these old systems a lot here. 
Also, I first suspected something amiss in the ceiling/roof from roofers or the PV installers but as I broke down the area into isolated runs, I found the same fault in the ceiling as well as a run from the ceiling down to a switch box maybe 5' away, energizing sections one at a time.
I only mention the PV system because it was in my head and if I pull a new circuit, there is room for me to get it from the PV utility and that is the only part of the house with modern grounding.
The thing that is getting me is the weird readings with my meter on a GFCI that had only the hot and the neutral attached, the ground screw left vacant. I was getting 120ish hot to neutral, less than 0V hot to ground (this is all through the face of the recep) and 64V ground to neutral. I would have chalked it up to GFCI weirdness (I don't fully understand how they work) but the client claims he can feel it (voltage?) through the metal chassis of his laptop as a slight buzz when he gently rubs a finger across the casing. I've recommended that he leave the circuit off until we can find a solution but he's pretty cheap and not real patient.


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## don_resqcapt19 (Jul 18, 2010)

DesertDawg said:


> ...
> The thing that is getting me is the weird readings with my meter on a GFCI that had only the hot and the neutral attached, the ground screw left vacant. I was getting 120ish hot to neutral, less than 0V hot to ground (this is all through the face of the recep) and 64V ground to neutral. ...


What are you using for a meter to measure that voltage? It sounds like phantom or ghost voltage to me.


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## Switched (Dec 23, 2012)

Do you have a solenoid tester?


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## readydave8 (Sep 20, 2009)

So you're not getting your voltage reading to ground, you're getting it to where the ground would be if it was there?


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## telsa (May 22, 2015)

1) 0 VAC hot to ground ==> The unconnected ground tab was pulled UP to 120 VAC during the measurement resulting in a reading between 120 VAC (hot) and 120 VAC (unconnected grounding screw) -- hence a reading of 0 VAC between them. Your DMM can pass enough juice to energize the grounding strap... it is not connected to anything... the ultimate 'floater.'

2) Weird mid-range neutral voltages such as those posted strongly imply that the neutral is not grounded back at the Service. It's a 'floater.'

The single, best, way to work this is to kill all hots to the entire zone -- and back feed the neutral with a toner. (Progressive EP-200 -- now Greenlee) and wand the circuit backwards. 

[ The neutral is presumed to be ungrounded or the toner will 'die.' ] 

As you wand/ trace the conductor backwards (flying along when it's visible on the surface) you'll entirely run out of tone where the neutral connectivity ends. (ie Where the problem is.)

Working without a toner and wand is sure to be frustrating and very slow going. You'd have to never miss a junction box and go back and re-make every single neutral connection until you've fixed the open.

BTW, you should run out and purchase a cheesy analog meter. The ones out of Taiwan go for the staggering sum of $13 at Harbor Freight. They also load the conductors enough to drain off induced phantom voltages. (aka capacitive coupling)

The reason why a neutral does not swing all the way UP to 120 VAC as you test it -- to produce a reading of 0 VAC on your DMM is that the EMF can bleed off into other devices. 

Your meter only passes a trivial amount of current. This amount is so feeble that it is dissipated. 

( Very much like charging a capacitor, as it fills up the neutral conductor like it's one pole -- one capacitor plate.) 

Hence the neutral tap is lifted to only (120VAC - 64VAC = ) 56 VAC over ground -- the actual voltage of the un-landed neutral at the point you're reading it. 

[ And, of course, a well grounded neutral would stay at 0 VAC -- so the meter would read ( 120VAC - 0VAC = ) 120 VAC hot to neutral/grounding electrode conductor system. ]


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## backstay (Feb 3, 2011)

This is basic electrical 101. A hot conductor, a neutral conductor and a ground conductor. Like others have said, if you're using a MM, you will not find your problems. You will chase ghosts.


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## DesertDawg (Jun 6, 2013)

Right, this is what I was looking for. Constructive advice. I'm not really a spectacular technician but have some sense of linear logic and deductive reasoning. Yes, I was using a pretty basic Sperry DMM. And I am pretty used to phantom voltages although 64 is a little on the high side of what I've seen. And yes the neutral is a "floater" . The old panel is not grounded. I realize now that I could have just run a "wild" ground out to the solar utility where a proper ground has been installed, for purposes of testing. There are actually a bunch of tests I should run (that I actually know how to run) that I didn't because the client doesn't want to spend a bunch of money on troubleshooting. I already gave him an hour and a half for the price of one just because he is the son of a good client. And because that's how long it took me to tear down and isolate the circuit, test a bit, and reassemble it.
Is the ground aspect of a GFCI somehow electrically connected to other aspects of the device? Could some level of residual voltage potentially leak into the ground lug and ground prong receptacle? Or maybe it's an intentional "feeler" voltage like some dimmers put out that resolves itself when grounded?
Oh yeah, sorry, I read what you guys said and I'm still kinda processing. I think the next thing I do, if I get to do anything, would be that wild ground thing. If there is a short or shorts somewhere that would become clear very quickly.


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## macmikeman (Jan 23, 2007)

DesertDawg said:


> Right, this is what I was looking for. Constructive advice. I'm not really a spectacular technician but have some sense of linear logic and deductive reasoning. Yes, I was using a pretty basic Sperry DMM. And I am pretty used to phantom voltages although 64 is a little on the high side of what I've seen. And yes the neutral is a "floater" . The old panel is not grounded. I realize now that I could have just run a "wild" ground out to the solar utility where a proper ground has been installed, for purposes of testing. There are actually a bunch of tests I should run (that I actually know how to run) that I didn't because the client doesn't want to spend a bunch of money on troubleshooting. I already gave him an hour and a half for the price of one just because he is the son of a good client. And because that's how long it took me to tear down and isolate the circuit, test a bit, and reassemble it.
> Is the ground aspect of a GFCI somehow electrically connected to other aspects of the device? Could some level of residual voltage potentially leak into the ground lug and ground prong receptacle? Or maybe it's an intentional "feeler" voltage like some dimmers put out that resolves itself when grounded?
> Oh yeah, sorry, I read what you guys said and I'm still kinda processing. I think the next thing I do, if I get to do anything, would be that wild ground thing. If there is a short or shorts somewhere that would become clear very quickly.



A 64 v ghost reading is actually below avg. I see lots up in the 90 v arena using a fluke t-25. I keep a knopp wiggy on hand for those times. Try using one of those next time. And go buy a book on grounding vs bonding , from reading your post above regarding the pv system earthing, it sounds to me like you need to read up.


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## DesertDawg (Jun 6, 2013)

Yeah, your right, but ouch! I haven't spent much time actually educating myself in this trade and now I've got one foot out the door anyway so I've got a lot of self education to do that has nothing to do with electrical. And my brain is getting old. But I will say that I fixed a lot of bad stuff and my client list is sure going to come in handy.


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## backstay (Feb 3, 2011)

DesertDawg said:


> Right, this is what I was looking for. Constructive advice. I'm not really a spectacular technician but have some sense of linear logic and deductive reasoning. Yes, I was using a pretty basic Sperry DMM. And I am pretty used to phantom voltages although 64 is a little on the high side of what I've seen. And yes the neutral is a "floater" . The old panel is not grounded. I realize now that I could have just run a "wild" ground out to the solar utility where a proper ground has been installed, for purposes of testing. There are actually a bunch of tests I should run (that I actually know how to run) that I didn't because the client doesn't want to spend a bunch of money on troubleshooting. I already gave him an hour and a half for the price of one just because he is the son of a good client. And because that's how long it took me to tear down and isolate the circuit, test a bit, and reassemble it.
> Is the ground aspect of a GFCI somehow electrically connected to other aspects of the device? Could some level of residual voltage potentially leak into the ground lug and ground prong receptacle? Or maybe it's an intentional "feeler" voltage like some dimmers put out that resolves itself when grounded?
> Oh yeah, sorry, I read what you guys said and I'm still kinda processing. I think the next thing I do, if I get to do anything, would be that wild ground thing. If there is a short or shorts somewhere that would become clear very quickly.


I know it sounds like I'm being hard on you, but I fix this stuff everyday. Open or high resistant neutrals should be easy to spot, harder to find. A open ground doesn't have an effect on how a circuit functions.


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## telsa (May 22, 2015)

He stated 64V ground to neutral.

He also stated the ground was unconnected.

He never stated that he took the 64V reading from a true ground -- but he might have.

His apprenticeship is incomplete, indeed.

*backstay*

"Open or high resistant neutrals should be easy to spot, harder to find"

They are freaking obvious with a toner and wand. It can't pass a decent signal past an open... nor a _highly_ resistant neutral connection. 

( Beyond a certain point (of conductivity) the toner can't even get up enough signal to follow, granted. Truth to tell, I've never run into that kind of circuit fault. )

Based upon my local experiences, very, very, very, few j-men have a toner and wand in their tool suite. It has not caught on. The typical j-man assumes that these are strictly for signal and telephone circuits.

{ On every job I've ever been on, I was the only fellow who had one. Not having touched one, worked with one, most don't have a clue as to what I'm talking about.

Recently, drastically inferior circuit finders have been sold into the trade. Not knowing better gear, most j-men take these 'electronic cripples' to be the best on offer. A circuit identifier is not rigged to find open neutrals... which is the overwhelming need that a toner and wand scratches.}

At about $120 for a set, you can't afford to NOT have yours. 

They are such an obvious addition that Greenlee bought out Progressive so as to offer them to the wider trade.

None-the-less, their utility goes right over the heads of most. 

It only takes the first demonstration... then every j-man wants one.

Yes, they've been out on the market for decades.

Doh!


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## RIVETER (Sep 26, 2009)

backstay said:


> > [ A open ground doesn't have an effect on how a circuit functions.]
> >
> > I like the way you speak.


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## Bad Electrician (May 20, 2014)

Without seeing the job, I am having trouble putting together in my mind the exact layout.

BUT it seems a small room with a small amount of boxes.

Open all the splices and ring continuity between hot, neutral and ground, and end to end make a drawing of the wiring, as you clear it remake each splice.


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## kg7879 (Feb 3, 2014)

Unless I missed something how can you get a voltage reading from one point that is connected to another point that is not connected to anything? It is impossible.


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## macmikeman (Jan 23, 2007)

Ancient Electrical Scripture- it goes something like this- '' with a digital multimeter and no low z switch, all readings are possible.''..........


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## bkmichael65 (Mar 25, 2013)

kg7879 said:


> Unless I missed something how can you get a voltage reading from one point that is connected to another point that is not connected to anything? It is impossible.


It's not only possible, it's straight textbook electrical theory


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## kg7879 (Feb 3, 2014)

bkmichael65 said:


> It's not only possible, it's straight textbook electrical theory


I must of missed something then because I can not see how the OP could of got a voltage reading from a neutral to the grounding terminal that was not connected to a grounding conductor.


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## backstay (Feb 3, 2011)

kg7879 said:


> I must of missed something then because I can not see how the OP could of got a voltage reading from a neutral to the grounding terminal that was not connected to a grounding conductor.


We'd really question a voltage reading from ground to neutral with a ground wire connected!


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## telsa (May 22, 2015)

backstay said:


> We'd really question a voltage reading from ground to neutral with a ground wire connected!


High impedance D.M.M. produce such bizarre readings (of phantom voltages/ capacitive coupling) every day of the week.

Indeed, the way the OP wrote -- none of us is quite sure WHAT tests and connections he's made.

Everything about his predicament is consistent with an over confident handy man -- someone who's never been apprenticed.:whistling2::no::whistling2:


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## Ibewye (Apr 24, 2012)

telsa said:


> He stated 64V ground to neutral.
> 
> He also stated the ground was unconnected.
> 
> ...



I got one !!! You it use for not only what your mentioned but speakers (it'll actually play a tone through the speaker your wired to, and tracing out existing thermostat wiring behind walls. Like you said, no one seems to get the benefits like I do. 


Sent from my iPhone using Tapatalk


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## Black Dog (Oct 16, 2011)

Switched said:


> Do you have a solenoid tester?


A low Z tester would get rid of the phantom voltage too.


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## Newintowntoo (Sep 28, 2012)

But a real electrician uses a "wiggy"


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## RIVETER (Sep 26, 2009)

telsa said:


> High impedance D.M.M. produce such bizarre readings (of phantom voltages/ capacitive coupling) every day of the week.
> 
> Indeed, the way the OP wrote -- none of us is quite sure WHAT tests and connections he's made.
> 
> Everything about his predicament is consistent with an over confident handy man -- someone who's never been apprenticed.:whistling2::no::whistling2:


What do you think a PHANTOM VOLTAGE is.


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## telsa (May 22, 2015)

RIVETER said:


> What do you think a PHANTOM VOLTAGE is.


Don't post while drinking. :no:


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## RIVETER (Sep 26, 2009)

telsa said:


> Don't post while drinking. :no:


How did you know?


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