> The stranded Al wire doesn't have the same propensity for failure as
> 'solid conducter' Al, I'm not a physicist so I don't know why.
It has to do with what is known as "cold flow".
When you make a connection using solid conductor Al, you have a good
solid mechanical connection; however, the Al oxidizes which increases
When current flows thru the wire, the Al wire heats up slightly and
the Al wire softens slightly and begins to flow or ooze, thus reducing
the amount of clamping force provided by the termination which causes
increased electrical resistance.
Increased resistance causes increased "cold flow" which causes
increased resistance, etc, etc, ultimately leading to the wire
melting, and then a fire.
BTW, the wire usually melts about 2"-4" from the termination, usually
up inside the insulation. Don't have a clue why.
There are many variables to the above process, so the amount of time
req'd varies greatly.
Infrequently used circuits may not malfunction for many years, perhaps
never, but you never know.
Stranded Al cable OTOH, uses special terminations, potted with "sheep
dip" to prevent Al oxide from forming, and special crimping tools to
insure a good termination.
It is a totally different world, but the increased termination cost is
quickly recovered by using lower cost Al vs copper for large cable
Same can not be said for small, 30A max, branch circuits found in a
home, for example.