Re: All circuit breakers off but still have power

[herganorris74]

I have a strange one I’m replacing a lot of switches & outlets down stairs when I cut the power test the outlets and switches all is good however when I was trying to work the up stairs I turned the breaker off and with test plug it into all the outlets tester showed no power so pulled a cover off standard porcelain light to replace it with a switch I test the wires again before starting both the black and white showed red but the flasher was beeping slower than when power was on I decided to check the outlets same thing there. I checked the tester again nothing I put my multimeter on no voltage when I use the power tester all wires show red or hot I have two new testers and checked them both on it and a circuit elsewhere they are working you thing I have another circuit wire in I turned all the circuits off in the rooms around it no difference same problem in my bedroom with bother breaker

[Bob Smith]

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[gfretwell]

replace it with a switch I test the wires again before starting both the black and white showed red but the flasher was beeping slower than when power was on I decided to check the outlets same thing there. I checked the tester again nothing I put my multimeter on no voltage when I use the power tester all wires show red or hot I have two new testers and checked them both on it and a circuit elsewhere they are working you thing I have another circuit wire in I turned all the circuits off in the rooms around it no difference same problem in my bedroom with bother breaker

Short the hot to the ground, if no sparks, you are just seeing induced voltages. No big thing. It is a product of the very high impedance test equipment we are using these days.

[herganorris74]

Short version breaker off all outlets and switches are off when I open the I used two new meters and both white and black short hot according to the meter but outlet and multimeter showed no power this also happened in another room on another breaker but on the same flloor

[chrisgking68]

I have a GFCI that keeps going bad. So this time I put a multimeter to the wires instead of using a voltage tester that just beeps. What I found is the hot (Black) wire from the circuit breaker panel has approximately 12 VAC on it, even when disconnected at both ends. I pulled the wire back and forth in the conduit to try to move it if it was shorted to another wire, but that made no difference. There are 2 other hot wires running through the same conduit. when I shut either one of those off the voltage drops to about 4.5 and when I shut them both off it is zero. I assume this is inductance. Short of running the wire in a separate conduit can I fix this and is it what is causing my GFCI's to fail.

[Ralph Mowery]

it if it was shorted to another wire, but that made no difference. There are 2 other hot wires running through the same conduit. when I shut either one of those off the voltage drops to about 4.5 and when I shut them both off it is zero. I assume this is inductance. Short of running the wire in a separate conduit can I fix this and is it what is causing my GFCI's to fail.

Most anytime you have wires next to each other there will be a small voltage in the wire not connected. Many digital meters will show some voltage, but this is what most call induced voltage. Either by capacitance or inductive coupling. Nothing wrong with the wiring.

That voltage is nothing, you should see it in a plant that has a dozen or more hot wires and in 200 or more feet of conduit. I have seen nearly 120 volts in it, the same as the wires with power on them. Enough current to give a good shock to you.

I doubt that voltage would cause the GFCI to fail. You should probably look for another cause.

[trader_4]

+1

What is the failure mode of these Gfcis? If there was some unusual surge that hits them, then I could see that damaging the electronics.

[gfretwell]

I

it if it was shorted to another wire, but that made no difference. There are 2 other hot wires running through the same conduit. when I shut either one of those off the voltage drops to about 4.5 and when I shut them both off it is zero. I assume this is inductance. Short of running the wire in a separate conduit can I fix this and is it what is causing my GFCI's to fail.

You are chasing ghosts (ghost voltage in this case). This is not why your GFCI is failing. First, what is wrong with the GFCI? You may really have a wiring problem. Does it fail to reset? Is it a breaker or a device box type? Does it fail with the load side wires disconnected? Start there.

[Clare Snyder]

Inductive or capacitive - virtually NO current capacity, and NOT causing the GFCI to fail. 99.9999%

[TimR]

If I get 120 VAC on my multimeter, I trust it. If I get 12 or 37 or anything else weird, I turn the digital off and go get the Simpson. It's not as convenient but the old analog doesn't seem to get fooled by phantom volts the way the digitals do.

If the analog shows the same reading, then I've got a wiring problem. I've never actually had that happen though.

[trader_4]

Some new digital VOMs have dual inputs now, high and lower impedance to solve that problem. I think someone reported here that there were adapters, essentially a resistor bridge that you could plug in to older Flukes, etc too.

[Ralph Mowery]

I have seen my Simpson 260 show close to 115 on some wires that are around the same voltage. However this was in conduit around 200 or more feet long and about 10 or 15 other wires in it.

One thing I found out is that on the 260 that if I started off on a high voltage scale and stepped down in voltage scales, if the meter stayed in the same physical position or near it, then it was the phantom voltage.

[Clare Snyder]

My old analog high impedence meter used to show "phantom" voltages too. Holding one probe in each hand cancelled them out - as it does on a digital meter if it is capacitive or inductive. At 37 volts even if it is NOT phantom - and is real leakage, it is generally not much more than slightly unpleasant - - -

[trader_4]

And if it's not a phantom voltage, it can cancel you out. A resistor across the inputs seems like a better idea.