Bob,
thanks for the answer. Actually, the aluminum oxidizes at the joints or splices. The resistance of these joints can go really high. This translates directly into heat. That means when you fire up your A/C, the wire splice starts to heat up and act like a light bulb, but without the bulb.

There are places where aluminum is used withspecial fittings and such, but I suspect its not for us amateurs. And no, I would not buy a house with AL wiring, nor would I use it in a trailer.

One place it is used is here in ohio, from pole to house....that's AL with some kind of stranded wire that is the ground. At the weatherhead, there is a transition from AL to CU, that uses special compression fittings. The electrician who did mine had a small electrically pumped hydraulic crusher thing that made the actual joint. That's the closest i want to get to AL wiring.
thanks,
denny