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Aluminum wire

Dec 20, 2016

Aluminum wire has been used as an electrical conductor for a considerable period of time, particularly by electrical utilities related to power transmission lines in use shortly after the beginning of modern power distribution systems being constructed starting in the late 1880s. In the early 1960s when there was a housing construction boom in North America and the price of copper spiked, aluminumbuilding wire was manufactured using utility grade AA-1350 aluminum alloy in sizes small enough to be used for lower load branch circuits in homes. Aluminum wire requires a larger wire gauge than copper wire to carry the same load or current, but was still less expensive than copper wire for a particular branch circuit.

In the late 1960s problems and failures related to branch circuit connections for the newer building wire made with the utility grade AA-1350 alloy aluminum began to surface, resulting in a re-evaluation of the use of that alloy for building wire and an identification of the need for newer alloys to produce aluminum building wire. The first 8000 series electric conductor alloy, still widely used in some applications, was developed and patented in 1972 by Aluminum Company of America (ALCOA). This alloy, along with AA-8030 (patented by Olin in 1973) and AA-8176 (patented by Southwire in 1975 and 1980) perform mechanically like copper.

Unlike the older AA-1350 alloy previously used, these AA-8000 series alloys also retain their tensile strength after the standard current cycle test or the Current Cycle Submersion Test (CCST), as described in ANSI C119.4:2004. Depending on the annealing grade, AA-8176 may elongate up to 30% with less springback effect and possesses a higher yield strength (19.8 KSI for a coldworked AA-8076 

A home with aluminum wiring installed prior to the mid-1970s (as the stock of pre-1972 aluminum wire was permitted to be used up) probably has wire made with the older AA-1350 alloy that was developed for power transmission. The AA-1350 aluminum alloy was more prone to problems related to branch circuit wiring in homes due to mechanical properties that made it more susceptible to failures resulting from the electrical devices being used at that time combined with poor workmanship.