black wire jacket with rainbow sheen

I've got this wire running through my wall that has a bit of a rainbow sheen to it. I feel like that's probably an indication the wire has gotten a bit toasty in the past and should be replaced.

Is this a sensible reaction, or is this wire pretty normal? The house was built in the 70s and I'm assuming this wire is the same age.

  • Groovy! Toasty wire usually looks toasty. if it's not stiff and brittle it's safe. It could be leaching plasticizers or oils. A cheaper fix, if you're dead-set on it, would be to upgrade the breaker with AFCIs so that if any insulation did one day fail, your wiring (the metal stuff inside) would be protected, and thus your whole house.
    – dandavis
    Jun 18, 2021 at 20:36
  • 3
    Zoom out a bit - not clear what we are looking at - a single wire, a cable, a bare copper wire with a bit of green corrosion, an insulated wire...
    – Ecnerwal
    Jun 18, 2021 at 21:17
  • What color is it in other places? Hard to tell from that photo
    – Ed Beal
    Jun 18, 2021 at 22:14
  • Is this a cable serving a circuit, a grounding electrode conductor, or...? Jun 19, 2021 at 0:01
  • Are you sure it's an electrical wire? does the sheen wipe off ? with water? alcohol? acetone? is it running horizontal or vertical?
    – Jasen
    Jun 19, 2021 at 0:48


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.