I know how to test polarity in receptacle wiring, but how can I test polarity in lamps or installed ceiling light fixtures? (Without actually taking the fixtures down again!)

  • 1
    You can use a voltmeter with one lead connected to ground. The center contact should be hot and the rim neutral. Of course, you have to remove the bulb.
    – BillDOe
    Commented Jul 22, 2017 at 22:46
  • @BillOertell -- make that an answer and I'll upvote it for you :) Commented Jul 23, 2017 at 1:58

1 Answer 1


Connect one lead of a voltmeter (since we're probably speaking AC here, which lead doesn't matter) to ground and measure for voltage at the center contact of the light socket and the rim. The voltage at the rim should be at or near ground (zero) and the center contact, hot.

As always, make sure you know how to handle test equipment and high voltage properly. If in doubt, hire someone.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.