Very small voltage from neutral to ground in GFCI outlet

[Frank L. Bartlo]

Last evening I inspected a house in which one of the bathroom GFCI outlets had a tiny (0.01 V) voltage from the neutral to the ground when the outlet was on, according to my voltmeter. There was no voltage when it was off.

I tested it with the voltmeter it because it had difficulty re-setting, and showed "open neutral" on the regular outlet tester when the reset didn't engage.

Since the neutral and ground should connect at the panel, what is the explanation for this?

It does not seem to be nearly enough voltage to indicate a hazardous condition, and I'm not one to make mountains out of mole hills. It seems to me its origin is in the GFCI outlet itself, perhaps in the switching mechanism.

Thoughts, anyone?

[jking2]

With zero load on the circuit, I would see any significant voltage as a problem, but 0.01 is so close to zero that I wouldn't call that significant.

Jim King

[Richard L. Bennett]

GFCI is bad because of problem with reset

A small voltage difference is normal and not related

The report call is the GFCI fail to reset

rlb

[rromoser]

Pinch one lead in each hand or poke both leads into a potato and you will most likely read "voltage" Digital meters can be very sensitive. Sometimes too sensitive that they will give unusual readings.

[Marc D. Shunk]

Originally Posted by rromoser

... Digital meters can be very sensitive. Sometimes too sensitive that they will give unusual readings.

Quick, one-page read on so-called "Phantom Voltage", that every digital meter user should have in mind.

[Greg Fretwell]

If the wires you are measuring are terminated then you can believe what a digital meter says. It is when you have a wire that is not really connected to anything that it becomes a random number generator.
.01v on a lightly loaded circuit is a reasonable voltage delta on the neutral. It can really be up to around 3v and still be within the FPN recomended total maximum voltage drop on a 120v circuit (half of 5%)