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  1. #1
    Join Date
    Oct 2008
    Location
    Kansas City, Missouri
    Posts
    126

    Question Stray voltage when switch is off

    1935 storybook cottage

    I replaced my bathroom light fixture, wall mount over the mirror. There were several wires that were twisted together in the box and when the wall switch is on, I got 119V. However, when the wall switch was off, I got 18.4V on my Fluke. The wall switch was replaced by an electrician with a GFI switch/outlet combo.

    I'm guessing the reason there are 4 wires twisted together is one set used to go to the outlet that was commonly found on porceline bathroom light fixtures. I'm afraid if I try to twist it apart the wires will disentegrate. They're solid enough the way they are, but it looks like someone actually twisted, and then soldered them together.

    So, is 18 erroneous volts really a problem? Will bulbs burn out quicker if the constantly receive a small stream of voltage? Is it worth messing with or is there a chance I'll create more problems?

  2. #2
    Join Date
    Feb 2009
    Posts
    693

    Default Re: Stray voltage when switch is off

    You are using a digital meter, correct?

    What you are seeing is voltage that is induced in the wire much like how a transformer works. There is no current available to do any damage though. You could short it to a grounded conductor and not see a spark. This is very common when using a digital meter.

    No problem.

  3. #3
    Join Date
    Oct 2008
    Location
    Kansas City, Missouri
    Posts
    126

    Default Re: Stray voltage when switch is off

    Yes, digital meter. Thanks for the reply. I didn't figure it would cause a problem but thought I would ask just in case.

  4. #4
    Join Date
    Jun 2007
    Location
    Shamokin, Pa.
    Posts
    645

    Default Re: Stray voltage when switch is off

    Quote Originally Posted by NEC View Post
    You are using a digital meter, correct?

    What you are seeing is voltage that is induced in the wire much like how a transformer works. There is no current available to do any damage though. You could short it to a grounded conductor and not see a spark. This is very common when using a digital meter.

    No problem.
    NEC, you beat me to that answer.

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