Topic: 0.02 Volt AC

[eigenvector]

Ran into something while repairing an outlet the other day.

Ants got into the outlet box and started making a home   So, rather than give them a chance I opened up the box, dusted them with diatomaceous earth, waited a bit, vacuumed them out, then replaced the outlet since it stopped working (GFCI type).

So I measured the volts before - 120 VAC (to make sure my meter was working), tripped the breaker - measured again - 0.02 VAC.

I have never seen that on this meter before and it scared the heck out of me.

Ultimately the outlet was replaced without incident - but what to do about that 0.02 VAC?  Could that be chalked up to a phantom reading, a problem with the breaker, or problems with two circuits possibly touching each other in the wall somewhere?  (thinking about those ants...)

[Duke McDukiedook]

Did you wire the outlet correctly when you hooked it up?

[eigenvector]

I wired it up incorrectly - but only because I was on LSD and heroin that day.   

 

I have no reason to believe it was wired up incorrectly.  There's nothing complicated about this particular circuit - a single wire run from outlet to outlet.  I have my lights and outlets on separate circuits.  I didn't even do the original wiring - that was done by a competent electrician whom I trust.  I was just repairing the circuit.

I'm willing to accept that this is just a phantom reading.  This particular VOM has been around the block a few times and it wasn't top of the line when I got it.

[Duke McDukiedook]

I was asking because that is the problem when I wired a GFCI outlet in my bathroom downstairs when it kept tripping the circuit breaker.
It is definitely particular about how you wire the outlets up to hot and neutral and could be giving you strange reading on your voltmeter.

[eigenvector]

I don't believe that's it - however I won't discount it.

That said, if the electrician messed it up I'd be surprised.  In fact it would be tough to mess up - this particular outlet I replaced it with actually had on it "black wire"  "white wire". 

I suppose the thing to do now would be to trip breaker for the outlets - measure again.  I have a second VOM that I can compare against.  If it comes up 0.00 or the like - toss the old VOM and get a better/new one.

[CycleRanger]

It's likely just induction.
Your meter is supposed to be sensitive enough to pick that up, that's normal.

[Duke McDukiedook]

Like you said it also could be a voltmeter going wonky on you.
You don't know until you know for sure.

[TwoTired]

As a test, what does your meter read if you hold the probes on the insulation jackets of the white and black?

Are your meter leads laying parallel to the ac wires?

What meter brand and model?  What scale are you using?