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.
Good point! I did indeed find 30 volt both hot-to-ground and
However, I believe I can explain the neutral-to-ground voltage very
simply. The reason I was opening up the junction boxes in the basement
and checking voltages was that I was having some wacky behavior with
most of the circuit out but a few of the compact flourescents dimly
lit. It turns out that one of the neutrals had slipped out of the wire
nut. This could explain the induced current in both the neutral and
the hot since with the breaker off they were both effectively
Let me know though if you think I am missing something.
Roger that, I think you're on track now. If you reconnected that neutral
wire nut and left the breaker open I'd bet dollars to donuts that you'd
still measure "something", but now less than 30 volts, with that meter
between hot and neutral or hot and ground, but nada between neutral and
ground. (Because the capacitance between the hot and neutral in that run
would form the lower leg of a capacitive voltage divider and shunt some
of that stray current to ground.)
Glad you got it fixed though!
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."
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?
No question that magnetic fields can induce voltages Doug, but they are
unlikely to be anywhere near as large as 30 volts in house wiring
because the outgoing and return current carrying conductors are so
physically close to each other that their magnetic fields cancel almost
completely and don't leave much of a net ac magnetic field to induce a
voltage in another nearby conductor. And, I would expect that since the
ground lead is also in close proximity to the hot and neutral leads in
typical house wiring that magnetic field would induce a near equal
voltage in it too, bucking out the voltages induced in the other two
wires, leaving little voltage to measure between them.
It's genberally capacitive coupling which causes those "phantom low
current voltages" on disconnected conductors in houses.
Things can be different in industrial applications where currents can be
much higher and the wire runs a lot longer. For example, running a three
phase circuit between two boxes in three separate pieces of metal
conduit instead of a single larger conduit because a hack installer
didn't have any large enough pipe with him (and didn't know any better)
might not seem dangerous at first thought. But, as soon as some
significant currents are put through those conductors they induce
currents in the three conduits, which, since they're electrically
onnected together at both ends by the walls of the boxes, act like a
shorted 3 phase transformer secondary. The three conduits can get hot
and often will start arcing where they join onto the boxes.
At any event, the OP found the problem, an open connection in the
neutral lead at a wire nut. The degree of "seriousness" of that defect
in his house wiring is debatable.
(W1BSV + Brass Rat '57 EE)
"As long as there are final exams, there will be prayer in public
_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
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.
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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.
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