I’ve never seen wiring like this before. If this was a switch I’ve seen black to white but this is odd to me. I’ve tested the lines there hot. And I don’t know if this has anything to do with the outside motion light above. If I put a GFI here and run back to gold and neutral to silver, this makes me think I should reverse it on the other side to match this odd wiring?

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  • 6
    You need to trace out the circuit and check the wiring at both ends before you do anything.
    – JACK
    Jun 19 at 12:30
  • 2
    Could be anything from switch loops tied together to deliberate reverse of hot and neutral to???? Need to see the other ends to figure out Jun 19 at 12:33
  • 2
    No, something different and special is happening here. It might even be a 240V circuit. Jun 19 at 19:07

1 Answer 1


That looks simply wrong, from what we can see in this one junction box. But I agree that you have to look further to know what and how it's been done wrong before assuming or jumping to conclusions and screwing things up more.

Black to white on a switch loop is common, but swapping both black and white - no. Not how it's done. Supply hot black joins to switch loop white, (which should be re-marked as a hot) switch loop black switched hot joins to fixture black hot, supply white neutral joins to fixture white neutral.

Also looks very much like 12 AWG to 14 AWG, which means it's OK if 15A breaker and a code violation if it's a 20A breaker. Either 14 AWG needs to be replaced with 12 AWG or the breaker needs to be 15A.

The box appears not to be connected to the ground wires, (no box pigtail, just the two grounds from the two cables, and the grounding lug on the box is empty) so that needs to be corrected as well.

As to your original question of whether you can put a GFCI receptacle here, "Probably, after you sort out this mess by looking elsewhere to find what's connected to what, and probably correct something."

Though we'll recommend putting the GFCI protecting this location somewhere inside (between the breaker and this location, or as the breaker) and protected from weather, as even "weatherproof" GFCIs don't hold up all that well to life outside.

  • The small/thin grey and white seem to be together, which seems odd. If they are from a fixture, can NA fixtures use grey and/or white as something other than neutral?(besides in switch loops)
    – crip659
    Jun 19 at 13:15
  • 2
    @crip659 I would call all the wires I see here black, white (if somewhat aged/filthy) and bare. Nothing here I'd call gray/grey. I think you are seeing an illusion due to the angle of the picture. The fat white passes through the split end of the smaller black/white cable on its way to an obscured entry to the same cable as the fat black. Also, the box needs to be grounded.
    – Ecnerwal
    Jun 19 at 13:22
  • Quite possible, I see the fat black, the shiny thin grey, the dull grey box and the two white wires, plus grounds. Was a picture months ago with a screw, look at it and had a recess slot, next time looking at it, had a high ridge/bar.
    – crip659
    Jun 19 at 13:48
  • @Ecnerwal Yea I think your all right here, I expected I was going to have to do some tracing before I do anything. However what do you mean by put the gfci portion on the inside?
    – Ryan
    Jun 19 at 18:08
  • 1
    @Ryan He means inside the house instead of on the outside. GFCIs don't like weather so much and tend to die earlier when outside. Put the expensive GFCI inside and it will protect a cheaper outlet outside.
    – crip659
    Jun 19 at 19:08

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