marksheivers: Aluminum Alloy - The What's, Where's and Why's

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When first found in branch circuit wiring, aluminum wire was not installed any differently than copper. Because of increased copper costs in the mid 1960's, aluminum wiring became more prevalent in wiring homes. It had been known during the time that aluminum wire requires larger wire gauge than copper to hold the same current.

For instance, a typical 15-amp circuit breaker wired with No. 14 gauge copper requires No. 12 gauge aluminum. Typical connections from electrical wire to electrical devices, also known as terminals, are often produced by wrapping the wire around the screw terminals and tightening the wire or pushing the wire through the rear of the outlet. As time passes, several terminations to aluminum wire begun to fail due to improper connection techniques and dissimilar metals. These connection failures generated heat under electrical load and triggered overheated connections plastic aluminium foil.

Aluminum wires have been implicated internally fires by which people have already been killed. Reports of fires with aluminum wiring generally reveal that poor workmanship led to failures. Poorly made connections were too often the cause. There were several possible reasons why these connections failed. Both core reasons were improper installation and the difference between the coefficient of expansion between aluminum wire and the termination found in the 1960's.

Feeder and branch circuit wiring systems were designed primarily for copper conductors. Aluminum wiring was evaluated and listed by Underwriters Laboratories for interior wiring applications in 1946; however it was not used heavily until 1965. In those days copper shortages and high prices made the installation of aluminum branch circuit conductors a very attractive alternative. At the same time frame, steel screw became more common than brass screws on receptacles. As aluminum wire was installed more frequently, the found that changes were needed to boost the method of connecting and terminating smaller aluminum wire. Installation methods for utility grade aluminum , or series AA- 1350 alloy were also different and workmanship was an important factor to make reliable connections.