Last night my wife turned on a recessed light in the shower. Shortly after, the light buzzed, got brighter and started smelling so she turned the light off.

I took it apart today and see something I never saw before - a black rubber piece attached to the metal electrical box. I originally thought this was perhaps a sacrificial thing if a wire touches the metal box but the breaker didn't trip. This was the cause of the smell - it was burning.

Will end up replacing all this stuff just in case but what's the black rubberish thing called and what's it's purpose?

My house was built in the US in 1985.

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"GTE RP" https://i.sstatic.net/3y9Kf.jpg

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  • Believe it or not I have found live conductors cut off in attic, walls and crawl spaces the first few times it freaked be out , not safe but sometimes a wire gets cut and it is never disconnected.
    – Ed Beal
    Aug 9, 2020 at 16:19

2 Answers 2


To me it looks like it could be a thermal cutout switch, which is designed to interrupt the circuit if the light fixture overheats.

  • 7
    If true, (i am not saying it isn't) then the irony of an overheat protection device overheating is sweet.
    – Alaska Man
    Aug 9, 2020 at 17:41
  • 2
    Yep, that's what it is! Why it melted is beyond me... I'm reading that they do occasionally go bad. Some of the comments here have also been insightful. amazon.com/gp/product/B00VRN7B4M but @AlaskaMan has a great point lol Aug 9, 2020 at 18:30
  • Might also be a badly blown fuse holder. Aug 9, 2020 at 19:41

The piece to the left is a cord that has been cut it looks like it had a strain relief / clamp but that’s what it looks like to me I say cord because the cable looks to me to be a cord and the conductor colors not normal for my location U.K.? Possibly. The wire nuts not normal for the U.K. I think. The new photos don’t look like cut cord. I have never seen a thermal cutout not part of the fixture. But getting several down votes now that more photos show up we will have to see what it is. There is fixture going in the flex but again I have not seen a thermal cutout not part of the fixture or even in the j box.

  • 1
    It's not a cut cord. The end has "GTE RP"... Like a brand stamped into it. It was definitely something made like this by design. There's no electrical tape or anything wrapped around it. I'll add another picture. Also my house was built in the US in 1985 (added to question), Thanks Aug 9, 2020 at 17:18
  • Then I would guess a surge suppressor I have never seen a thermal overload for lighting that large. It it is a surge suppressor it is not unusual for them to blow when they take two large of a hit. This in the wall or behind the Sheetrock would not make sense for a humidistat but that is another possibility.
    – Ed Beal
    Aug 9, 2020 at 18:02

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