We run a different system over here to you guys, so I am not going to tell you what to do....I will however share my experienced opinion. We use the MEN system here - Multiple earthed Neutral, which means that every installation has it's own main earth (ground) point - rod or bare copper laying in a trench, and the main earth is tied via an MEM Link at the main switchboard....not the Meterbox. This link can be removed for performing a variety of tests. All the points along the National grid use this main earth system, so effectively, the entire country has a grid tie to earth. Particularly useful to determine if a grid supply transformer is at fault rather than your own installation ( I had that happen once) We also have 230Volts at 50Hz for single phase and 400Volts for 3-phase. So our cable sizing is basically half of what the USA sizing is, for the same current carrying effect. This makes for smaller switch-gear and easier installation.
In my experiences of Aluminium cable (we spell it different also) it is seldom used in domestic situations. It is chiefly used where a run of cable is far in excess of the norm. Example was a house I wired about 10 years ago - I needed a 60Amp 3-phase supply. The run was approx 70 meters (77 yards - or 230 feet) I used Aluminium for the bulk of the run and tailed down the last 3 feet at each end. This was done mainly as the cost of Copper the entire run was roughly $10k vs around $3K. The only thing was, instead of running a 4-core 25mm copper cable, I had to run a 4-core 70mm Aluminium cable....so three times the size, as the current carrying capacity is less in Aluminium for the equivalent size in Copper. Way cheaper, but heavier to handle and dress the cable. The trench work was in mixed material - gravel, soil and builders droppings, so the 25 metre run was encased in conduit. Once inside the house it was simply strapped to the framework all the way to the switchboard. Tailing down meant I had to use special Aluminium to Copper barrier links with compound inside the Aluminum side....and resin filled heatshrink, boots and overall sleeving into the underground pit outside - and into the meterbox upstairs. From the meterbox was just a short run of Copper cables.
Having a friendly Inspector and a capable apprentice on that job made for a magical install - apparently it was the first time a real Estate Agent had been able to go to a house and turn everything on, and not trip a breaker to take the photos.
IMHO, for a short run like this ...I would run Copper - for nothing more than making life easier on the job. Nothing wrong with Aluminium, it's just more work, and more care on the job is required.
It's not always about price.
