Dave Plowman (News) wrote:
In article ,
The Natural Philosopher wrote:
I suspect its a subspecies of this:

http://www.barbadosrc.org/misc/blackwire.php

which is well known, if not so well understood.

I suspect myself its electrochemical attack of copper due to three
things: damp, a salt, and a voltage.

Since I do quite a bit of work on old cars, this is common. But how or
why I dunno. One cable in a loom will have it - another not. Cable from
the same maker. But not as bad as shown in that article - more just a
coating on the individual strands. Which makes a good insulator...


the key is whether the insulator allows wet salt in, and whether its in
the negative side of something that can leak..