mulit strand copper wire

Throw it away and pull in new.

Take measurements afterwards and verify ampacities/voltage.

Copper is not cheap, but sometimes it is necessary to replace conductors.

You can clean up terminations and such, but if the insulation is gone, get new wire.

K T

_{Lets see. Brittle. No longer malleable?} Result of high heat or chem contamination.

_{Insulation burnt over some portions?} Result of high heat or chemical exposure.

I suggest the following: Your wire is being used to carry Hydrochloric acid. The temp required to make it possible to move HcL through the wire is just too much.

Use larger wire. Reduce load. Call electrician. Do not call chemist - he will think you are nuts. (I pass no judgement)

Do so soon. Potentially serious hazards await.

To a little degree yes, but much of it would depend upon its' manufacture. IE: Bad or out of spec wire would throw this way out of wack. I pulled this from the first site I saw so I'm not sure if it's accurate:

So if these numbers are correct(AWG), and the wire(s) are to these specs; then the wire(s) in question where probably pushing around 10A's or more for them to get burnt and brittle - and it probably was for some period of time. Any higher current would probably melt the insulation fairly quickly but that would be dependant upon what type of insulation was used. Also, I thought that there was a temp range, but can't think of it now - but that would be a factor too especially since you've noted that it was burnt. There are many factors which I don't know about which could determine it's past performance. Oh, then there's the 'time' factor - IE: How long they've been installed and then how long they where under the 'fault conditions.'

I agree, replace the wire with same and check current draw.If you are getting high current, find out why and fix it, don't just put in heavier wire. ( I've seen this done. Really bad idea!) Be sure ALL connections are tight,as loose connections can cause high resistance (and sparking). High resistance = high current draw and heat. Also sparks cause lots of other problems.

BTW is this wire stationary?

<...infer anything from its past heating and/or current carrying capacity?...>

Certainly: it has carried more current than it is able to do without overheating, and requires replacement.

Persistence may include fire, injury and fatality among the outcomes.