Why outlet makers warn against aluminum wires?


Hi
I am looking for an answer as to why there are always warnings on high-end outlets regarding using them with aluminum wires?I use mine (Shunyata Venom) with al.wires and felt the quality jump right away compared to PS Audio i used before.Both outlets manuals say:Do not use with aluminum wires!Why?Thank You for your responses.
overhang
Two issues: Aluminum is more likely to oxidize (corrode or rust) when in contact with certain materials like certain other metals. The oxidation presents increasing resistance at the contact points which causes heating and can lead to fires. Studies have shown aluminum wiring in houses is statistically more likely to lead to fires than copper.

Secondly, aluminum tends to expand and contract more than other materials with changes in temperature, which can lead to loosening of connections over time. To prevent this, either use aluminum-to-aluminum connections or fasteners that resist this type of loosening.

Both of these issues are potential problems that become concerns as time passes. We should weigh them against any sonic benefits that may be audible immediately.
IIRC, aluminum in-wall wiring has been implicated in fires due to oxidation of wires where they attach to outlets. I would GUESS that this is a cya statement
Hope this helps
http://www.cpsc.gov/cpscpub/pubs/516.pdf
BTW I was UL tester during this time of my life and I remember the stir that AL and AL clad wire caused.