I have repaired lots of underground, almost always is an ungrounded conductor that I have repaired unless someone physically did some damage, like with excavating equipment or driving a post or similar item into it.
I’ve had the opposite experience, almost always the grounded conductor in direct burial cable. Now in conduit, it’s always the ungrounded conductor.
Copper, aluminum, either?
Yeah. I was hoping the cord could be salvaged. I cut back a foot, then 5 feet. After deciding to junk it I even cut into near mid way out of curiosity. IMHO the grounded conductor looks overheated throughout.
Perhaps. I've never seen new cord with one conductor that looks like that but I haven't seen it all. I do feel like I can tell when copper has been overheated. Beside the blackening and duller color you can see in the pic, when I fan out the individual strands and flatten it, it has the darker red color that's always indicated to me excessive heat.
Yeah, same here. I've heard some explanations from guys who have also noticed it happens with the grounded conductor much more often but nothing plausible.
Just a wild guess but wonder if the coloring agent or dye they use to produce white insulation has an effect on the copper. Black insulation might use common lamp black to produce that color. According to a Google search lamp black is very stable & unaffected by light, acids & alkaloids.
"looks overheated" is the point.
Or maybe the white insulation melts at a lower temp.
But that only affects multiwire circuits. Thats why you find an oversized neutral on office furniture.
And mostly only the neutral on systems supplied from a wye secondary.
