In a few boxes in my house, I've found a some of these things that serve the purpose of wire nuts. They are made of rubber and have a loop on the bottom. They wrap between the wires, and then around and up over the top. If you pull them off, the wires inside are held together by a separate a metal clip.

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What are these things called? Are they safe, or should I replace them with regular wire nuts?

  • 2
    These were used for years and unless they are dried out and cracking they are just as effective as wire nuts. They would be more expensive to buy and install now, hence they are mostly obsolete. Oh and the slang term is barrel crimps and diapers.
    – ArchonOSX
    Commented Apr 27, 2018 at 19:49

2 Answers 2


That is a rubber insulated open end crimp. They can be removed without cutting the wires.

  • 1
    Ideal makes them and call them Wrap Caps.
    – Paul Logan
    Commented Apr 28, 2018 at 5:06

If they were loose or otherwise not making good contact, then you would see signs of heating, e.g., burned insulation on the wires or the insulating cover of the crimp cap. Absent those signs, no reason to change them.

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