"Dave Plowman (News)" wrote in message
...
In article ,
John wrote:
I'd say free particles of a contaminant such as iron in the copper
would be a more logical cause

Presumably then that tube wouldn't meet the appropriate BS?


Probably not but IIRC there was a choice of cheap imported (Polish I
think) stuff or none at all at the time so it was used. Its only after
a number of years that the chickens are coming home to roost

But surely the copper shortage was many, many, years ago? Rhodesia
declaring UDI in the Harold Wilson era?


Whatever the reason Dave it became "bad to get hold of" at odd times since,
and yes I recall the shortage you mention which affected everything and
resulted in a lot of aluminium cable being sold. There were various failures
with surface corrosion and "Copperclad Aluminium conductor" small sized
cable was introduced but it seems to have died out again fairly soon after.
Large CSA cables and busbars employing aluminium are still used today but it
requires competent installation.