Like I have said before, I have never seen Al conductors of small cross section in domestic wiring.
There used to be a reference to copper clad aluminium conductors in an older edition of the wiring regs.
I think they may have been used during a copper shortage in the early 70's.
I have seen a Cu clad Al conductor once only in my 20 years in the trade. It was used as a main earth bonding conductor to the water service in a house rewired around 1970, this cable was sized 10mm at a time when 6mm Cu would have been the norm.
