My new house in the US has a Harbor Breeze combination fan/light switch with a remote control as seen here (different brand is shown, but it's basically identical). While checking some wiring (unrelated), I pulled the switch out of the wall and saw to my surprise that the wire leads coming out of it appeared to be aluminum (the house has copper wire). The wires aren't visible in the previous link, but you can see the same thing here on the page for the receiver. My understanding is that aluminum wiring is no longer done residentially and that it's a very bad idea to mix copper and aluminum unless you really know what you're doing. So what gives? Are these wires not actually aluminum, or are switches an exception for some reason?
Edit: In response to requests for more information, careful visual inspection doesn't reveal any copper color, even in cross-section, but the wire is braided and the individual strands are so thin that it's difficult to even see the cross section. That in itself probably rules aluminum out. Markings on the wire are:
E108485-S 18AWG FTI -F- REI HSING CSA TEW 105oC 600V LL84687 AWM 1015 VW-1
Those codes led me to this pdf, which says "tinned Strands, copper conductor, 7/0.254mm strands." So I guess that's the answer. Next time I'll know to search for the codes before bothering people here. :)