Re: very low voltage -- dangerous?

benjunk@xxxxxxxxxxxx wrote:
I'm doing some rewiring and have run into some confusion. I have a
240V circuit, which, when on shows about 240V on my multimeter. When
I flip it's breaker, though, it shows some number of mV (instead of
0). This confused me.

I mentioned this to someone else, and they asked what the amperage was
when the breaker was off. Seemed like a good question. So I went and
picked up a clamp meter that detects amperage. It showed 0. This
seemed strange, so I called the company (Ideal) and they said I had to
put a load on the circuit to detect any amperage. Ok, but that
defeats the point...

Or does it? Maybe that it says 0A when the breaker is off, combined
with a few mV means it's not a problem at all?

Put a load on the circuit, turn off the breaker, then measure -- it will almost certainly show you 0 volts as it should. If you see voltage under these circumstances _then_ you have a problem of some sort. As others have pointed out, you can not blindly rely upon a high-impedance meter in home-wiring situations since they can measure capacitive leakage across open contacts and between adjacent conductors.

--
John McGaw
[Knoxville, TN, USA]
http://johnmcgaw.com
.

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