Digital meters can read voltages at *extremely* low currents. *Any* device that produces a magnetic field can induce an electrical current on wires that pass near it. Unexpected currents of less than line voltage, when read by digital meters, should be verified with an analog meter before leaping to the conclusion that there is "a serious defect in the home's wiring."
-- Regards, Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?
It takes about 70 volts to set off the neon bulb testers. It also takes almost no current for them. Induced voltage will very easy light them up. I use the testers almost every day at work in a large plant. I have seen the tester light up, read about 100 volts on a Fluke digital meter and about 20 volts on the good old Simpson 260 analog meter . While I don't think it will really hirt you, I can tell you that it will make you hirt yourself, especially if you are hot and sweaty.
If a nutral is loose and feeding back on it, you can get almost the full voltage and almost the full current of the circuit it is connected to.
Thanks -- as pointed out in another post, I ended up tracing problem back to loose wire nut (that was just installed by a licensed electrician no less).
I hope that this explains everything, including the dimly lit compact flourescent, so that there are no other problems I need to look for now that everything seems to be fixed and working properly.
Interesting about the Analog meter -- my parents were going through some of my childhood stuff and found my circa 1974 20+ range Archer multimeter (there were no digital ones then). I would have thrown it out other than for sentimental reasons, though it sounds now like I should keep it!
Suggest do the testing as I described anyways just to be certain--though I havent followed this thread completely and so its unclear to me what you did find as the cause.
But yes I do prefer to use the older meters. I dont much care for having to de-cipher phantom readings, or having deal with a scale value that won't settle in to some reading that actually makes sense...with an older meter, the needle generally swings into position reliably and repeatably.
_Even_ with a digital meter. Hint: neutral and ground are _supposed_ to be shorted together at the panel. Unless there's a break in the neutral or ground, even a digital meter shouldn't see that much difference between ground and neutral.
Showing 30V hot to ground or neutral, when the breaker is off, is where the impedance of the meter matters.
[Worst case difference between neutral and ground, assuming the circuit is in operation is about 1.5% (allowable voltage drop at full current thru the neutral).]
The OP's measurement of .7ma is also too high for impedance effects. It'd be a few microamps or less.
Redo your problem Nick, your problem solving for was for a single conductor, and measuring voltage end to end. Not for two(or more) conductors running side by side, and measuring voltage at one end. The voltage induced in one conductor, would be exacly the same as the induced in the others, therefe for no potential would exist between the conductors(as in OP's story) where the voltage should be sensed, between the conductors and an immediate grounding source(not the ECG, since that is one of the parallel conductors).
I'll give you an A for effort, Faraday would be proud. :-P
BTW, the NEC covers taking steps to minimize induced voltages and inductive heating, even for common fokes, it gives enough information about how running conductors close together will reduce/elminate it. Just that I see often that digital meters show voltage, on dead legs, and I've chatted with others about how to ensure you have no juice left. One smart chap said, cind the ECG and Neutral are bonded, why not bond the ungrounded(hot) conductors, we cam up with an idea that you can bond all three with a shorted out three prong plug. Now voltage should be ZERO, but we figured come time to close the breaker, we would forget it in place, and melt it. ;)
Not the way I read it Tom. The voltage measured end to end on that isolated conductor would be zero.
I believe he was describing a single isolated conductor running near one with an ac voltage on it. The 95 V he mentioned would be measured relative to the other side of the ac source swinging that powered conductor (Which would of course be "neutral" and/or "ground" in a home.) That voltage would be the same anywhere along its length.
He really should have described the most likely case; that the isolated conductor in a home wiring system would be a black wire in a length of Romex and the white wire and ground leads in that Romex would be connected to the other side of the ac source (ground). So, there would be a fair amount of capacitance between the isolated conductor and the two grounded ones in the Romex, probably more than the amount per foot he estimated for a "nearby" powered conductor. That would create a capacitive voltage divider, so the voltage measured on the isolated conductor couldn't possibly reach the 95 V level he mentioned.
Not for two(or more)
Twisting the conductors really helps with the inductive heating stuff.
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