ACSS is a composite concentric-lay stranded conductor. Steel strands form the central core of the conductor with two or more layers of aluminum 1350-O wire stranded around it. The steel core carries most or all of the mechanical load of the conductor due to the “O” temper (fully annealed or soft) aluminum. ACSS (Aluminum Conductor Steel Supported) is very similar to ACSR (Aluminum Conductor Steel Reinforced). But, as their names imply, ACSS depends primarily on the steel core for support, whereas the ACSR is supported by both the aluminum and steel components.