With the primary purpose being power distribution, the aluminium conductor cables are more often specified over copper conductors in 6/10kV networks in external installations not restricted by space, whilst cables running inside buildings tend to be copper as space is limited.
10kV cables have a copper wire screen (often with a copper tape in counter-helix) offering a degree of mechanical as well as limited electromagnetic protection, but it's main purpose is for earthing. The cables are unarmoured - any installation direct into the ground would need to be subject to national regulations.
