Switch Off And 40V...thoughts?

DetailHandyman

Discovered this when replacing a ceiling fan (in my house) last week. This one has me confused...

Overhead pancake box, power fed to this box and passes through to several other OH lights. Two 3-way switches controlling this fixture.

With either switch off, get 40V hot to neutral, or hot to ground, neutral to ground at 0V. Full 120V with switch on.

3 ways are wired correctly. And even with 3 way pulled out of circuit (just checking wires at OH box), same results on hot cable into box.

I don't what is upstream of this box...haven't gotten ambitious enough to trace cables in the attic yet.

All neutrals at main panel are tight and do not read 40V at receptacles in the house. (well, at least the few I checked). I have not pulled apart any other lighting fixtures on this circuit to check for 40V.

What could be causing this?

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480sparky

Illuminated switch. Dimmer and/or speed control.





Why is it a problem?

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Magnettica

I would guess it's just some phantom voltage. I really don't know. I have come across this myself on occasion and what I did was - and otherwise never do - is short the wire to ground. If there's no fault current that you have phantom voltage.

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DetailHandyman

Yeah, that was my thought...there is a dimmer on one other light. But I put the meter on that and I get no voltage leaking through when it's off.


Not really sure if it's a problem. But I figure if there is always 40V on the line, then any light that I install will always be on...wasting electricity. I never noticed if this was a problem with the previous ceiling fan as it had a frosted dome over the lights. They may have been on very low, may not.

I'm just kinda interested in what's going on. And frankly, I like "off" to be "off".

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The cat box ain't gonna clean itself.

DetailHandyman

To be clear, you're saying run hot to ground, if breaker doesn't pop, then I 'm getting voltage, but no amperage, thus no real problem? Makes sense. I'll give that a shot tomorrow.

I know one of the wires running into this box is in a huge ass bundle of wiring strapped to the attic floor. This bundle includes all the 240V cables to range, etc and probably 75% of the other branch circuits in the house. Not a nicely combed and separated bundle either, just a pile of wires basically.

You got me thinking, maybe some induced current on this cable? Although why wouldn't I see this elsewhere in the house?

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The cat box ain't gonna clean itself.

mdshunk

You were using a digital multimeter, weren't you?

http://www.nema.org/stds/eng-bulleti...ulletin-88.pdf

DetailHandyman

Thanks MD.

I was using a Fluke 87 for the testing. But first picked up the "off" voltage with a non-contact tester.

Am I legal here?

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The cat box ain't gonna clean itself.

1mancrew

I bet once the fan is wired up...you will show no voltage between the hot and neutral.

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