Ground short problem.


Old 03-16-05, 09:38 PM
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Ground short problem.

Here is a problem that is absolutly driving me crazy.
I have wired a few houses of my own so I am familiar with wiring.
Here is my problem.
I am using a small tester with a light,it has a red and a black wire with 2 pins on the end.They are very common and cheap.
I was testing my ground circuits and found my cheap test light about 1/2 bright on one of my ground circuits.There is a possibility that that circuit wasnt grounded back to the box.On my Fluke I got about 50 volts but not enough amps to actually shock you.
This is on 10 ft of 14/2 romex with all 3 wires unhooked and exposed.
Is this normal.I also hooked up 20 ft of rRomex and put power to it and got 100 amps on the Fluke but no shock potential.
When I fully ground the ground wire back to the panel the test light goes out but then I dont know how to see if there is anything at all flowing back to the panel.
Is this just incidental voltage jumping across to the ground wire due to the fact that the wire has full voltsge to it but no where to go?
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Old 03-16-05, 09:43 PM
Join Date: Sep 2000
Location: United States
Posts: 18,497
No, it's not normal. But you really didn't tell us what two points you put those two pins on, so I don't really know what test you conducted. It would also be interesting to know why you even were doing this testing. Did you have some sort of operational problem?

You got 100 amps?? I don't understand that at all. Did you mean 100 volts instead?

What do you mean "no shock potential"? Does that mean you touched the wire and didn't get shocked?

Are you familiar with the concept of "phantom voltage"? If not, google the term.
Old 03-17-05, 05:24 AM
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
I suspect you are seeing phantom voltages. And I too hope you meant 100 volts, not 100 amps.
Old 03-17-05, 09:39 AM
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I think the "phantom voltage" is what I am seeing.
Here is a clearer picture.
I had a box with multiple wires running to it.It had 2 switchs for lights and 2 wires that just basically ran the power through it to another set of lights that were switched in another box.I just had one home run running to this box.
There were so many ground wires that I didnt make a complete hookup of one of the grounds back to the panel though i though I did.
Apparently the circuit that I got 50 volts on the ground side was a circuit that had power but no ground return.
This confused me.The 100 amps I mentioned was actually 100 volts!
And yes I did touch the ground wires that showed the 50 volts and 100 volts and I got no shock.
What I did was basically put a 20' and a 100' wire with the black to power from the panel and the white and ground unhooked from anything at both ends.The 20' gave me a Fluke reading on the ground (this is between the ground on the test wire and the ground going back to the panel, the tester was between these 2 wires) of 50 volts then the 100' (actually it might have been 200' because it was the roll of wire I was using out of the package) the same test gave me 100 volts.Neither had enough amps to shock me or even fell anything.
I am sorry about this odd thread but I spent 2 days chasing this thing not realizing that electrons can jump through the insulation on a wire with power to it but with no place for them to go other than the tester.
Old 03-17-05, 09:58 AM
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Touching electrical wires that may be live is not a good idea. If the wires are live, you may end up dead.

The electrons don't actually pass through the insulation. Rather, the voltage reading is induced by an electromagnetic field. It's not an easy concept to grasp, and many people get caught by it when trying to find a problem with their electrical wiring.
Old 03-21-05, 09:55 AM
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Thanks for the advice.
Sorry about the late thank-you but I had to jump on the rest of the wiring.
You definitly were right on.

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