Should I have current in my ground

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Old 03-05-09, 12:32 PM
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Should I have Voltage in my ground

Many of the plugs in my house show voltage when I plug my voltage meter into the ground hole on a receptacle. I was replacing a plug with the breakers in a sub panel turned off when I first detected this (felt a tingle in my fingers). I just bought this house and have a fair amount of experience replacing plugs, switches, installing a little wire mold, but I've never noticed that crossing the ground with the neutral creates a circuit in any other house. Usually it's 25-50v, but in some cases, always when I check the ground to the neutral, it's 120v.

Is something horribly wrong with my electrics? Is there any way I can clarify to help you help me?
 

Last edited by variable; 03-05-09 at 02:35 PM. Reason: fixed title for clarity
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Old 03-05-09, 01:07 PM
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Can you tell the age of the house and wiring methods? What type of meter are you using to detect voltage and between what 2 points are you measuring voltage?

It sounds like you may have a bootleg ground.
 
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Old 03-05-09, 01:28 PM
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Wiring

You may have a hot and neutral reversed somewhere upstream from the receptacle in question. I would use a receptacle tester similar to these to check for correct connections at the receptacle:

Ideal Circuit Testers & Receptacle Testers
 
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Old 03-05-09, 01:39 PM
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Your subject line mentions "current" but your question mentions "voltage". These are two very different things.

The reason pcboss asked about the age of your house is that he suspects, as do I, that you simply don't have any grounding.

He also asks what TWIO (yes, two) points you were measuring voltage between. Voltage is a relative measurement and voltage at one point can only be measured relative to some other point. It is important that we understand what that other point is.

You might want to brush up on "phantom voltage". Google that term and read up enough so that you understand it.

You may have any of the conditions mentioned above (no ground, bootleg ground or hot/neutral reverse). We don't know which one until we have the answers to the questions asked by pcboss. Note that he asked THREE questions. Be sure to answer them all.
 
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Old 03-05-09, 02:42 PM
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>Can you tell the age of the house and wiring methods?

It's a 1920 house with a relatively new breaker box. All the wiring that I'm working with fed by new, 10g wires running in conduit from the main panel to a subpanel, then 14/2 Romex breaking out from there.

>What type of meter are you using to detect voltage and between what 2 points are you measuring voltage?

I'm using a GDT-11 multi meter (https://www.hardwareworld.com/Digita...r-p9W7C97.aspx) and I am testing between every 2 points I possibly can.

> It sounds like you may have a bootleg ground.

If it is I can't find it. I ran my own Romex and had the same result, running the hot and neutral from the breaker and neutral bus to the plug. Then I attached the ground wire and it had voltage when I checked it against both. Could a bootleg somewhere else be causing this result on new plugs connected to the neutral bus?

In my main breaker the ground is bare copper wire tied to the neutral bus, but all my plugs do not have this problem.
 

Last edited by variable; 03-05-09 at 02:55 PM. Reason: typo
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Old 03-05-09, 02:53 PM
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>He also asks what TWIO (yes, two) points you were measuring voltage between.

To be specific, I am measuring in the breaker box between the neutral bus and the bare ground wire (clamped to nothing) and getting 120v, then I measure against the hot and get around 50v. At some of the plugs around the house I measure between the neutral and the ground and get 120v and the hot and the ground and get around 50v. Other plugs I get no voltage between ground and the other openings. I pulled a plug out of the wall and touched the wires with the same result. Then I pulled the plug off the wires and only the hot and neutral gave me voltage. This has been repeated across the house, even with a brand new plug I ran from an empty breaker using 14/2 romex. The ground was screwed to the plug, but otherwise touching nothing else.
 
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Old 03-05-09, 04:26 PM
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Turn off all of the branch circuit breakers. Do the voltage check. Then turn them on one at a time and take a voltage reading. Is there a grounding electrode wire connected to the incoming cold water pipe?
 
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Old 03-05-09, 04:46 PM
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I'm using a GDT-11 multi meter (https://www.hardwareworld.com/Digita...r-p9W7C97.aspx) and I am testing between every 2 points I possibly can.
Wrong type of meter. Best to use a test light or analog multimeter. Digital meters can show phantom voltages. Do you have a separate ground bar and neutral bar in the sub panel? Is the neutral bar in the subpanel isolated from the breaker box? Does the sub panel have four wires running to it?

At the receptacles where you got voltage neutral to ground did you get voltage hot to ground?
 
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Old 03-05-09, 06:59 PM
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>Digital meters can show phantom voltages.

I understand the phantom problem, but this is showing a full 120v in some cases, and it was strong enough to shock me.

>Do you have a separate ground bar and neutral bar in the sub panel?

No, there is no ground bar. In testing I ran the ground straight back to the conduit that the main breaker ground runs to (which is also tied to the neutral bus). The ground wire is staked to the ground then switches back to the water pipes.

> Is the neutral bar in the subpanel isolated from the breaker box? Does the sub panel have four wires running to it?

If by isolated you mean not touching anything else in the box, yes, none of the power poles show any sign of continuity. There are four wires running to the sub panel, two hot, one ground, one neutral.
 

Last edited by variable; 03-05-09 at 08:00 PM.
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Old 03-05-09, 08:19 PM
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>Do you have a separate ground bar and neutral bar in the sub panel? No, there is no ground bar.
By modern code there must be a ground bar bonded to the subpanel. If no ground bar where are the ground wires in the panel connected?
is the neutral bar in the subpanel isolated from the breaker box? Does the sub panel have four wires running to it?

If by isolated you mean not touching anything else in the box
I mean not touching the metal of the box. Use your multimeter to check between neutral and a bare metal spot on the box. If you have continuity it is not isolated. It must be isolated. Usually there is a bonding screw or strap that must be removed.

I can't say if any of the above is the cause of your problem but the problems with the subpanel must be corrected. If you still have problems then we can go from there.

Edit: When I detailed how to check the neutral bar I forgot to say all neutral wires have to be removed. Sometimes the obvious is not so obvious if your not used to doing it. I need to remind myself of that more often. Thanks DaveC72 for reminding me of that.
 

Last edited by ray2047; 03-05-09 at 10:34 PM.
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Old 03-05-09, 09:45 PM
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Cant test isolation of ground /neutral in a working subpanel (nothwithstanding this odd situ here).. as the neutral and ground are connected at the main panel anyhow.. so zero ohms.
This must be visually verified. In the subpanel, where all the white wires go to, there may/not be a strap wire or solid bar that connects the neutral bus to the subpanel body metal. In a main panel this must exist. In a subpanel this must not exist.

Very odd (and seriously dangerous !!) situation you have.

Sounds like no ground connection, with improper wiring or some fault. Turning off all the circuits and proceeding from the beginning sounds like the best bet.. like what if you kill the whole subpanel feed at the main. Do the main circuits measure properly then ? Then turn off all the sub's branches and just test the subpanel itself, etc..
 
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Old 03-06-09, 05:27 PM
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I added a ground bar to the sub panel and screwed all the ground wires to that. I checked the ground that runs back to the main breaker, where it's tied to the neutral bar. That runs to a ground stake then ran back to the cold water main, but it ended there, so I clamped it to the water pipe.

I also confirmed that the Neutral bus is isolated in the sub panel, its grounding screw is absent and it's insulated with plastic on all sides. Of course, since the ground is screwed into the neutral bus at the main breaker I expected some continuity, but there was none. There is still a bit of voltage, around 25v from the neutral bar to the ground, and from many of the plugs through the house (including both of the plugs running from the sub panel).

That said I bought myself a circuit tester and plugged in in and it lit up saying all was good. No problems with the ground or neutral. Should I be concerned about that bit of voltage my multi-meter is detecting from the neutral to the ground?
 
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Old 03-06-09, 06:55 PM
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If there is no continuity between neutral and ground, then the voltage you are reading between the two is likely phantom.

But something seems inconsistent. If the neutral and grounds are really bonded at the main panel as you suggest, then there should be continuity between the neutrals and ground at the subpanel. So either the bonding is not there in the main panel, or either the neutral or ground is compromised between the panels.

There are many ways a simple outlet tester can be fooled. It's not 100%.
 
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