Aluminium wire armoured cable Steel wire armour is only used on multicore versions of the cable. A multicore cable, as the name suggests, is one where there are a number of different cores. When cable has only one core, aluminium wire armour (AWA) is used instead of steel wire. This is because the aluminium is nonmagnetic. A magnetic field is produced by the current in a single core cable. This would induce an electric current in the steel wire, which could cause overheating.