> Normal use causes the aluminum to loosen at all connections due to
> thermal contractions and expansions at the joints.
>
> Aluminum is one of those materials that "cold flows".  If anyone ever
> tinned a stranded copper wire and put it under a screw terminal, they
> know about loose connections and cold flow.  It WILL get loose, no
> matter what the fixtures were designed for.

This should be why in USA they use screw and spring connections at the
power outlets. At the first time I saw a solid wire just inserted into
the spring blade contact I thought it was just a faster way to do the
wiring, even representing a very weak contact compared to what could be
if using the screw just aside the same power outlet.

It is some kind of a double fork where the solid wire enters but can not
gets out, it keeps a spring pressure electric contact to the wire.

Of course the screw connection would be much stronger, but... probably
for aluminum wire this is the answer.

Some of my house's power outlets (w/aprox 8 amps consume) needed to be
replaced right after 6 years of use, at the new ones I used the screws.
The previous wires got superheated and the isolation burnt at that
spring loaded contact...

By the way, some experiences with transformers using aluminum wire?  :)

Wagner.