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switch loop problem


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Switch loop to control ceiling outlet is hot on both ends. I thought I had a bad switch, but switch makes no diff.

Somewhere along length of loop (romex) the two legs have joined, like maybe a nail through cable or the like?

Are you using a non-contact voltage detector to determine this? If so, don't. They are worse than useless in troubleshooting switch loops. You'll always get "hot" readings everywhere.

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It's a fluke brand "sniffer" that reads hot or not...no continuity with circuit off.

Set it aside, it won't work in this situation. You're picking up "phantom" voltage from the adjacent wires.

Get a multimeter or a wiggy for this particular job. It won't lie to you.

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As coincidence would have it, this showed up in my email box today. It relates directly to this conversation:

http://www.fluke.com/fluke/usen/communi ... oltage.htm

They left out magnetic coupling. Either capacitive or magnetic coupling could induce stray voltages.

Marc

From the story attached by Jim, the Fluke Stray Voltage Adapter is a 3,000 ohm resistor. Not that complicated.

A bit of resistance in the probe reduces the stray voltage but would not have that effect on a live circuit.

Marc, I think magnetically induced voltage would be stronger and not affected by the little resistor. But not something we would encounter in residential, AFAIK.

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