discolored branch circuits

[jazzman]

Hi all,
A friend of mine is considering purchasing a home but the home inspector discovered some discolored wiring in the main breaker panel. My friend asked me for my opinion. It appears that the branch circuit neutral copper conductors (white) wiring and the bare ground wires are discolored. They look burnt even though the insulation is perfect. I checked all of the connections and they were tight. Could this be from a lightning strike or worse, Chinese drywall? Your experience is valuable to me. Please enlighten me. Thanks.

 

[jaggedben]

Hard to evaluate discoloration without a picture.

You say the insulation isn't discolored; maybe it's just not discolored yet. When I've encountered charred neutrals it's always been because there was a mutli-wire branch circuit where two of the hot wires were incorrectly wired to the same phase. A charred ground could be because of objectionable current, i.e. grounds and neutrals bonded at a subpanel.

Alternatively, it could just be a natural patina on the copper. (Got a picture?)

 

[junkhound]

If the insulation is flexible it is likely OK, if brittle, it was probably overheated or is very old.

The bare copper is likely simply long term oxidation, if dark black and there are 'flakes' or the coating is powdery, then the ground overheated sometime in the past.

Many years ago, before the day of hand held o'scopes or harmonic analyzers, and old hand told me the way to tell if there were large harmonic on a 3 phase system was if the white wire was brown. Not a condition in a home.

PS: In many older homes which housed heavy smokers, the 'white' wire is often yellow.
In old homes that once had a coal furnace, every wire can look black, including the inside of the box. Last year I redid the main disconnect (100A fuses with knife switch) and everything in the box was dark black, including the fuse housings. Stainless steel wire brushed all the copper and cleaned it up and looked like new, was really no reason to replace as no additional loads anticipated and low income house.

 

[Fulthrotl]

Hi all,
A friend of mine is considering purchasing a home but the home inspector discovered some discolored wiring in the main breaker panel. My friend asked me for my opinion. It appears that the branch circuit neutral copper conductors (white) wiring and the bare ground wires are discolored. They look burnt even though the insulation is perfect. I checked all of the connections and they were tight. Could this be from a lightning strike or worse, Chinese drywall? Your experience is valuable to me. Please enlighten me. Thanks.

chinese drywall would affect all copper in the entire house, i would think... so it's probably not that.