ACSS is used for overhead distribution and transmission lines. It is designed to operate continuously at elevated temperatures up to 250°C without loss of strength; it sags less than a comparable ACSR under electrical loadings; it is self-damping if prestretched during installation; and its final sags are not affected by long term creep of aluminum. The advantages make ACSS especially useful in reconductoring applications requiring increased current with existing tensions and clearances, new line applications where structures can be economized because of reduced conductor sag, new line applications requiring high emergency loadings, and lines where aeolian vibration is a problem.
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. Steel core wires are protected from corrosion by a zinc-5% Aluminum - mischmetal alloy coating. Corrosion protection should be selected to suit the environment to which the conductor will be exposed.
• ASTM B 856 Concentric-Lay-Stranded Aluminum Conductors,Coated Steel Supported (ACSS)