# Electrical-28 volts through ground

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• posted on February 19, 2006, 3:29 pm
I have one circuit in my home that I am getting 28 vols through the bare copper ground wire. This circuit has severallights on it. Any ideas what the problem could be? Even with the breaker off I am getting voltage. The electrical panel looks ok. Ed
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• posted on February 19, 2006, 3:50 pm
Ed Varin wrote:

First exactly how are you measuring this voltage? Between the ground wire and what?? What are you using to measure it? Why did you measure it? I am suspecting no real problems, but there is one thing that I can think of that could be a problem depending on the answers to my questions.
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Joseph Meehan

Dia duit
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• posted on February 19, 2006, 4:19 pm
Joseph, This circuit operates a light that can be turned on and off from two locations. With the power off I was changing a light switch when I kept getting a little "tickle" every time I toched the ground wire. I took a multi meter and measure the voltage from the ground to any other wire in the switch with all wires disconnected from the switch. The ground was the only wire with power in it. The was no voltage between the other wires. I go through light bulbs often on this circuit (every 6-8 weeks). Ed

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• posted on February 19, 2006, 4:24 pm
Also, I am reading 28 volts at the light fixture, this is between the ground wire and either the white or black wire. There is no reading between the black and white wire when the breaker is off. Ed

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• posted on February 19, 2006, 5:09 pm
Ed Varin wrote:

You probably have a (potentially dangerous) "floating (safety) ground."
If you're a novice, this would be a good time to call an electrician.

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• posted on February 19, 2006, 10:05 pm
Ed Varin wrote:

I don't like that tingle. It is a sign that you could be in for a real shock, maybe the shock of your life. There are several possibilities and two of them can be dangerous and one is safe. I wanted to know exactly what kind of meter you used. The older multi meters would not have picked up on the third type of voltage but most of the new digital meters will. This one can give you a tingle but is very unlikely to do any damage.
I will have to go on with the other two. One is a floating neutral that is transferring over to the ground some how. How I don't know but it would tend to indicate a second fault as well. This one is serious and is often accompanied by lights that seem to brighten and dim for no reason. The other is a failed ground and that could kill if you get between it and a proper ground.
Finding these faults is not all that difficult if you have a good idea of wiring, but if you don't it is best left to the professional. Remember that it is an indication of something that is not right in two out of three cases. That means you can't count on things that might usually be safe being safe. I suggest you call in the pro.

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Joseph Meehan

Dia duit
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• posted on February 20, 2006, 2:27 pm
Ed Varin wrote:

That is a clear indication that your ground wire is not properly connected. If the breaker is on you should see 110V between ground and the black wire, and 0 volts between ground and the white wire. Trace that ground wire back and see if you still get the voltage at upstream boxes.

--
Thank you,

"Then said I, Wisdom [is] better than strength: nevertheless the poor
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• posted on February 19, 2006, 5:22 pm
wrote:

It sounds like the ground is open somewhere between where you are checking and the panel and you also have something leaking back intro that ground from another outlet. You have to isolate every box on that circuit and check them all. It may actually be coming down from a ceiling box and they are notorious for being overcrowded and having bad connections.
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• posted on February 19, 2006, 6:31 pm
:I have one circuit in my home that I am getting 28 vols through the bare : copper ground wire. This circuit has severallights on it. Any ideas what the : problem could be? Even with the breaker off I am getting voltage. The : electrical panel looks ok. : Ed : : It sounds like you're reading a phantom voltage, one which is induced into the wiring by stray fields, and quite harmless. But you really should prove that. You really didn't give enough details to make a sound judgement.
One way to prove phantom voltage would be to turn on one of the light switches on the ckt. If it goes completely away, it's just a phantom voltage. If there is still any voltage left, then it's time to call a repairman or at least a friend who knows how to tell when he's found a phantom voltage: It's very, very common, especially when high impedance meters are used for the measurement. Someone asked a bunch of questions that I don't yet see answered; that would help a lot.
Pop
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• posted on February 19, 2006, 7:15 pm
Pop wrote:

Perhaps but is not an induced "phantom voltage" not enough to give one the "tickle"
IMO anytime you get a stray voltage reading AND the "tickle / tingle" feeeling, the problem is real.
cheers Bob
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• posted on February 19, 2006, 7:49 pm
: > :I have one circuit in my home that I am getting 28 vols through : > the bare : > : copper ground wire. This circuit has severallights on it. Any : > ideas what the : > : problem could be? Even with the breaker off I am getting : > voltage. The : > : electrical panel looks ok. : > : Ed : > : : > : : > It sounds like you're reading a phantom voltage, one which is : > induced into the wiring by stray fields, and quite harmless. But : > you really should prove that. You really didn't give enough : > details to make a sound judgement. : > : > One way to prove phantom voltage would be to turn on one of the : > light switches on the ckt. If it goes completely away, it's just : > a phantom voltage. If there is still any voltage left, then it's : > time to call a repairman or at least a friend who knows how to : > tell when he's found a phantom voltage: It's very, very common, : > especially when high impedance meters are used for the : > measurement. : > Someone asked a bunch of questions that I don't yet see : > answered; that would help a lot. : > : > Pop : : Perhaps but is not an induced "phantom voltage" not enough to give one : the "tickle" : : IMO anytime you get a stray voltage reading AND the "tickle / tingle" : feeeling, the problem is real. : : cheers : Bob :
True enough, but ... 28Vac shouldn't be anything most people would feel, but ... that would be a good indication of another problem. I don't recall anything about it "tickling" the OP, so I must ahve missed that part. Putting a load on the ckt, eg turning on one of the lights should show whether it's got any power behind it though. A solid 28Vac wouldn't light it up, but it would/should draw the voltage down to nothing if it's phantom; if not, then it's a very real problem, for sure. IMO, there's too little info to make any good analysis.
Pop
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• posted on February 19, 2006, 8:41 pm
Pop wrote:
<snip>28Vac shouldn't be anything most people

<snip>
I disagree. You can get quite a jolt from even a 12 volt source.
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• posted on February 19, 2006, 9:46 pm
How? I have been handling 12 volts and more for all my life and never felt anything. However, I understand that if you inject or puncture the skin with the wire, you can feel it, it can even be dangerous in this manner.
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• posted on February 20, 2006, 4:21 am
wrote:

It all depends on where you get it and the frequency. AC will jolt you more than DC and if you are well grounded taking the shot on soft tissue like yje inside of your arm it will bite you. I damn near got thrown off the fire control deck of a ship getting 36v @ 400 hz in the soft part of my wrist on a sweaty day. It knocked the pee out of me.
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• posted on February 20, 2006, 12:21 am

Under what conditions?
--
Mark Lloyd
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• posted on February 20, 2006, 1:50 am
Mark Lloyd wrote:

moist skin (e.g. sweat)
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• posted on February 20, 2006, 6:15 pm

12 volts can give you an even stronger feeling if applied directly to the tongue. 12V can hurt, but this is a common way of testing 9V batteries. A good one tastes like lemon juice without the lemon.
--
Mark Lloyd
http://notstupid.laughingsquid.com
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• posted on February 19, 2006, 10:18 pm
wrote:

Glad you have the second sentence, because this one had too many "not"s for me to understand it. :)

So all I would have to do in this situation would be to connect a 110V lightbulb from the ground wire to {another actual ground / the white wire / the black wire / ??} and keep the meter at the same points?
If the voltage drops to zero, no problem. If it stay about 10v real problem. ??
I've never noticed this problem so I don't want to buy a wiggy (willy?) for only one use.
Could I just use a low impedance meter, like one with a needle that is 20,000 or 50,000 ohms per volt. Would that load make the phantom voltage disappear?

Remove NOPSAM to email me. Please let me know if you have posted also.
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• posted on February 20, 2006, 12:02 am
First, excercise caution. Avoid touching wires, ensure your circuits are properly disconnected. Sounds like common sense, but a lot of people (especially the experienced ones) ignore it.
I'm not certain what the required methods of running multi-phased circuits using single neutrals are. Perhaps someone can let us know if this is/was common practice for house hold wiring. I have gotten the general impression its not. Just so your informed, it is possible to run multiple hots on various phases using 1 neutral. If you open 1 hot this will not cut the power on the neutral completly.
At this point I'll assume your taking an interest in how to solve the dilemma, or find out exactly what is wrong. So I won't pester you with the "shouldn't do it" concerns others may have.
A suggestion which no one seems to have offered is to compare the resistance of 1 ground with another seperate ground run. It would seem to me that if I had an open on a ground wire then I wouldn't see a low impedance if I checked against another ground wire.
Seeing how I can't stand dealing with stray voltages at the best of timies, I'll simply stay away from this item. (I generally deal with low voltage signalling wire, and find that using a drain wire helps reduce stray voltages for my applications.)
JW
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• posted on February 20, 2006, 3:06 pm

It's fairly common. At least until recently, all Canadian kitchen counter outlets HAD to be done with "multiwire branch circuits" (CEC terminology for multiple hots and one neutral).
The main techniques of importance with multiwire branches is that you ALWAYS pigtail neutrals.

If your ground and neutral are properly connected back to the panel, the most you're going to see (in terms of a neutral voltage relative to ground) is about 2-3V (circuit delivering max load). The ground should be unaffected.
If you _ever_ see a neutral-ground voltage of more than 2 or 3 volts, then something is definately wrong. "stray" (aka "induced" aka "phantom") voltages are indeed common when you use high impedance voltmeters - but these will _never_ occur between conductors that are currently "in circuit".
In a correctly operating circuit, the only time you'll see a phantom voltage is on a switched off hot. You can't conclude anything from such a measurement unless you can load the hot enough to short out the stray component.
In contrast, ground and neutral are supposed to be interconnected (back at the main), and neither are EVER supposed to be switched. Thus, if you see more than a couple volts between a ground and a neutral, then one of them is broken. The voltage _may_ be "stray impedance". Or it may be something with real punch behind it. Either way, there _is_ a problem.
One way to distinguish whether the problem is with the ground or the neutral is to measure the voltage between the offending ground, and something that's grounded on another circuit (or often a copper pipe). If you still see voltage, the ground is broken. If not, it's the neutral. If it's the neutral, the circuit won't be working at all. If it's the ground, certain devices on it (eg: metal-cased 3-wire devices) may have live cases.
Further, anything that gives you a tingle ain't stray impedance. It's been my experience that "tingle" is almost always a sign of "[near] full line current available, the resistance of your shoes are saving you from being thrown across the room".
--
Chris Lewis, Una confibula non set est
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