This is a very enlightening article on aluminum conductors. http://www.mikeholt.com/download.php?file=PDF/IA08703001E.pdf
I have been saying for a long time that they are trying to rehibilitate the reputation of aluminum wire. I was at an Alcan pitch at an IAEI meeting where they were pumping us hard about how wonderful the new aluminum alloys are. They handed out samples of the old stuff and the new so we could play with it. I will admit it is tough. We also got the “using a steel screw was the problem” story.
Baloney from the aluminum guys. However you constitute it, aluminum will still expand and contract more than copper, cause loose connections and start arcing.
Have you seen these connectors?
All we need now is double-gang boxes for single receptacle.
In Texas we call this a Blivit “cram ten pounds of sh*t in a two pound sack”
If you look at the expansion rate table you see
so you can see why aluminum with a steel screw failed. Brass screws actually tend to fall right in the middle. The new aluminum alloy is closer to brass than the pure aluminum that is 22. The other thing that Alcan points out is the regular lugs you see (the silver ones) are aluminum and they actually perform better with aluminum wire than with copper.
That is probably whjy you are told not to be concerned with stranded aluminum (8ga and up) since that will temrinate in a lug, not a bonding screw.
The same is true with the aluminicon device. It may seem bigger but the guys who have tried them say they use about as much space as a purple wirenut. Since you are pigtailing it is not really that hard to get it all back in the box. Barry’s GFCI example is certaily worst case. I have seen suggestions that fat devices (GFCIs and dimmers) should get a bigger wire count when computing fill.