I'm getting ready to replace the breaker panel in my condo and I found some scary damage in one of the cables coming into the box from the top, just at the knock out hole (see picture). The damage black wire seems to be almost gone. It looks like I would need to add a piece of wire to extend it to the breaker that is connected. what is the best way to do this? I should be able to do whatever is needed since I'll have the old breaker box off.

I've been living here for 18 years and that breaker (not AFCI/GFCI) has never tripped. I wonder if this happened before my time.

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  • Is the white insulated wire in that sheath OK or has it melted as well? – Michael Karas Aug 19 '18 at 15:50
  • This kind of damage would not be expected to trip a breaker. Somehow the insulation and the conductor got damaged, maybe when the outer sheath was cut. One scenario is that this created a high resistance leading to heating at the point of damage. Alternatively, or additionally, it could have arced to ground. – Jim Stewart Aug 19 '18 at 16:29
  • It seems likely to me that it had even ignited into actual smoldering flame at some point due to the black residue deposited on the side of the blue cable retainer. The green corrosion of the damaged wire and on the adjacent safety ground wire leads one to wonder what chemical reactions were going on over time in this area. – Michael Karas Aug 19 '18 at 16:51
  • @ Michael Karas: I don't know. I'm afraid to touch it until I'm ready to replace the panel. – Rodo Aug 19 '18 at 16:53
  • What was on that circuit? I do hope you have shut off the breaker to that circuit as soon as you discovered this. – Michael Karas Aug 19 '18 at 16:55

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