I am replacing an old light fixture. The junction box has no ground wire coming out of it. The instructions say that if this is the case to attach the ground wire from the light fixture to the green screw on the mounting plate.

Here is a picture of the old light where they have apparently done exactly that:

enter image description here

So how does this work? The ground has to lead back to the breaker box in order to work right? Is this mounting bracket connected to a wire leading to the breaker box?


Here is a pic of the inside of the box:

enter image description here

It does actually appear that the box has an attached ground wire leading out of it, so that's good news.

  • 2
    The hope, in this case is: fixture crossbar touches metal box, metal box is connected to either a grounding conductor or metal conduit leading back to breaker panel and ground rod. The problem is that often there is no such continuous path. That is why grounding conductors (or confirmed continuous path) are now required. Jun 10, 2020 at 5:43
  • Can you get us a photo of the inside of the box with the crossbar out of the way? Jun 10, 2020 at 11:54
  • @JimmyFix-it I see, that makes sense. I will see if I can get a pic of the inside of the box.
    – d512
    Jun 10, 2020 at 13:51

1 Answer 1


So long as there's no corrosion, the metal screws that attach the light's mounting bracket to the metal box are what provides continuity from the grounding wire attached to the metal box through to the ground screw and wire attached to the light fixture itself.

If your new light has this same set up (which is very likely), then you can continue to use the same system for your grounding.

If, of course, the metal box is not properly grounded (older installations often weren't), then this doesn't actually do anything, but it does make you feel better and provides a tidy installation of the ground wire from the fixture.

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