1. ## puzzler

While looking at a service equipment panel yesterday, I observed a black lead wire not connected to anything. So I pulled out my voltage sniffer to see if it was live ; it was not.

However, my sniffer pick up a signal from an equipment ground wire from a different branch circuit (lighting) from the above mentioned black wire.
I have one of those \$15 dollar sniffers so I was thinking I was getting a false signal...

...but for the sake of arguement, if I am getting a true voltage/current signal from the equipment ground wire, what would be the causes?

thanks,

b

2. ## Re: puzzler

Originally Posted by brianmiller
While looking at a service equipment panel yesterday, I observed a black lead wire not connected to anything. So I pulled out my voltage sniffer to see if it was live ; it was not.

However, my sniffer pick up a signal from an equipment ground wire from a different branch circuit (lighting) from the above mentioned black wire.
I have one of those \$15 dollar sniffers so I was thinking I was getting a false signal...

...but for the sake of arguement, if I am getting a true voltage/current signal from the equipment ground wire, what would be the causes?

thanks,

b
You are seeing inductive reactants. Current flowing in a wire next to the ground wire is induced into the ground wire. Very little current but enough to alert the sniffer. The other posibility is a reversed ground neutral connection.

Sniffers can fool you if that is all you use. i.e. If the power co. has removed power from the house by installing plastic insulators at the meter, your sniffer will indicate the power is on at the panel SEC. The use of a volt meter will show near 0 volts.

Last edited by Vern Heiler; 09-21-2011 at 08:05 AM. Reason: add other reason

3. ## Re: puzzler

Thanks, Vern.

So assuming the neutral and ground are not reversed, then there is no concern/ need to mention to homeowner?

b

4. ## Re: puzzler

Originally Posted by brianmiller
Thanks, Vern.

So assuming the neutral and ground are not reversed, then there is no concern/ need to mention to homeowner?

b
No need to mention false reading from sniffer.

5. ## Re: puzzler

I am not a fan of digital volt meters either for the same reason. As long as everything is ok with the circuit they work great. If you get a problem such as a loose connection the meter display can go haywire. I still use a analog meter for most of my troubleshooting.

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