Aluminium-sheathed cables

The use of aluminium as an alternative to lead for power-cable sheaths became a focus of attention to cable makers and users as a result of drastic curtailment of supplies and increase in price of lead which took place after the 1939-45 War. During the past six years significant progress has been made in its employment, and to-day several thousands of miles of aluminium-sheathed cables are in service. The paper reviews the development and assesses the value of aluminium as a sheathing material against a background of test performance and operational experience. Beginning with a brief summary of aluminium production and consumption figures, the paper proceeds to discuss qualities of the metal in relation to cable-sheath requirements. The historical background of aluminium sheathing is outlined and a brief description is given of the tube-sinking process originated in 1947. Standard sheath thicknesses of aluminium-sheathed cables manufactured by the tube-sinking process are recorded, their mechanical and electrical characteristics and performance are surveyed, and the advantages deriving from light weight and mechanical strength are presented. An account is then given of installation procedure and operating experience, including analysis of failures encountered in service and methods of dealing with jointing, corrosion protection and sheathexpansion problems. The authors claim that aluminium has been established as a technically suitable and economic sheathing material to replace lead, and that its availability at an economic level constitutes an important asset to the cable industry.