I'll echo any reports on not using aluminum wire for a grounding wire. Many
years ago, I used a large diameter (I think 1/10" diameter) aluminum
grounding wire when I lived in San Jose. We had a bad lightning storm in
the middle of the Santa Clara Valley, a very rare occurrence. We took a
direct hit and the grounding wire EXPLODED (as did nearby multi-stranded
aluminum power lines! I still have the samples.) leaving no ground return.
As a result, the bolt ran around the operating table blowing out everything
it could including my 75A4 front end! It also blew holes in the edge strip
on the table where it was near a filing cabinet (sitting on a heating duct)
and left a real foul odor (not to mention the shock of the loud bolt).