I am replacing a bathroom medicine cabinet that has a light fixture attached. The old light fixture only had white and black wires. The new light fixture has white, black, and a copper wire. This is a very old home, and I am assuming that nothing has any grounding. What should I do with the ground wire? Can I leave the ground wire just dangling? Or is there some way that I can/should ground it? It's not my home, and the homeowner will likely not want to pay for any extensive electrical upgrades. Suggestions?

  • If power reaches the fixture via solid metal conduit, that may be a reasonable safety ground. If not, and you can't pull new wiring through to provide that ground, another solution would be to have a ground fault interruptor earlier in the circuit... – keshlam Sep 3 '15 at 1:02
  • Another caveat that I ran into is that the fluorescent lamps (long tubes) that I have must be grounded because they use the enclosure as a RF shield. Leaving the case floating caused the light not to turn on reliably. – Pigrew Sep 3 '15 at 4:39
  • Do you have a cold water pipe running through the same wall? Do you have the room to run a copper grounding wire to a clamp on a nearby cold water pipe? – whiskeychief Sep 3 '15 at 11:22

Supplying the fixture from the LOAD side of a ground-fault circuit interrupter (GFCI), will provide protection to the fixture. It could be a GFCI receptacle, standalone GFCI device, or GFCI breaker.


Some electricians say leave it for future renovations when a whole house ground becomes available.

Other electricians say cut out the ground if there is no ground available because it takes up cubic space. In addition it might become energized and become a shock hazard.

I am a little hesitant to cutting it out with expensive dimmers as I might have to return them to the supplier in working condition. But 99℅ of the time I cut them out when there is no whole house ground.

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