I was changing a light bulb in a ceiling light fixture. I unscrewed the nut and removed the glass cover. When I was replacing the bulb I noticed that there was a copper wire loosely coiled around the center rod (threaded at the bottom...that's where the nut goes for holding the glass cover)

I'm assuming that's the bare ground wire. Is that adequate grounding. Does the wire need to be attached via a screw clamp...similar to what you see in receptacles?

I saw this with a couple of other fixture bases around the house.


Here are pictures of two fixtures.

fixture 1 fidture 2

The one on the right looks like the wire is screwed in AND the remainder is coiled around the post.

The one on the left...don't know where that wire is coming from.

Is there an easy way to test for proper grounding? I know that for receptacles I can plug in a device to tell me.

  • 3
    I don't think coiling a wire around anything is a recognized way of forming any electrical connection, ground or otherwise. Does this "ground" look like a "homebrew" addition, or the way the fixture was manufactured? (If so, that manufacturer needs a spanking) Can you post a picture?
    – AndyW
    Commented Jun 30, 2016 at 18:51
  • 2
    The fixture itself may actually be grounded to the box, but the ground wire was left unhooked. Many older electrical boxes lack the ground screw for it to attach to. Commented Jun 30, 2016 at 20:27
  • Is there a way for me to TEST the fixture that it is properly grounded?
    – milesmeow
    Commented Jul 6, 2016 at 7:40

2 Answers 2


The wire from above in the left picture is most likely coming from the Romex that powers the fixture, maybe attached by wire nut to ground at the end of the Romex.

This fixture looks fairly modern but I can't see the wiring behind it so unless you pull it down some and look (fairly easy) this is not enough info to be sure.

To answer your question, no, coiling around the post is not adequate grounding.


If the fixture is metal it should have a solid connection to the ground wire. There is usually a green screw in the fixture to secure the ground wire to. A photo may help us to pinpoint the best location to secure the ground.

  • 1
    Yes, typically this "ground screw" hole is a slightly different size than the nail holes in the box. It is tapped 10-32. You could drill and tap out a hole 10-32 (or 8 or 6 if you prefer). The thread pitch must be at least -32 because it needs enough threads to get purchase. Using a sheet metal screw is disallowed. Commented Jun 30, 2016 at 22:38

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.