When people began using electricity in homes, copper wire was used. Then in the 1970s aluminum wire largely replaced copper. After a few years, aluminum was replaced by copper again. Why did each change occur?
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ANSWERS: 4
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Aluminum was--and is--used because it is less expensive than copper. Aluminum does take some special handling, and it got a bad rap as a fire hazard. The problem is that the aluminum surface can oxidize into a poor conductor, compromising the quality of connections at outlets and switches, leading to heat buildup. It is necessary to coat the aluminum which is exposed by insulation stripping with an oxidation resistant material, and to use devices which have been designed to be compatible with aluminum. Aluminum is rarely used in smaller guage branch circuit wiring, but is frequently used for the heavier guage service wiring. So long as it is installed according to good practice, it works quite well.
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Aluminum wires tend to expand and contract to a far greater degree than copper. As a result wires would ''creep'' (move) under screws and wire nuts loosening the connection. A loose electrical connection leads to ''arcing'' igniting fires.
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It was thought that alum wiring was cheaper to install in homes and it was. But the electrical trade didn't take into account is alum doesn't have the same ampacity rating article 310 nec explains the differences it also is subject to expansion due to it alloy is much softer than copper and can't dissipate heat caused by resistance or lighting loads.
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I think they started using aluminum because it was cheaper. They stopped using it when they found out it is a fire hazard years later..
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