March 1948 Radio-Craft[Table of Contents]
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Radio-Craft was published from 1929 through 1953. All copyrights are hereby acknowledged. See all articles from Radio-Craft.
Aluminum wire's role in electronics and electrical service systems is an interesting case study. Early on, as this article reports, aluminum was seen as a panacea for harder to find copper sources and attendant price increases. Back in the early 1970s when I first began working as an electrician while taking vocational courses in high school, aluminum wire was being installed in low-end tract homes, apartments, and townhouses in order to save a little money. The National Electric Code permitted it at the time because it had not been in service long enough for its cold flow nature to manifest itself through loosening connection interfaces and eventual fires due to sparking under load. Brittleness after repeated stressing also caused arcing and resulted in fires, as did corrosion caused by dissimilar metals interfaces between the aluminum wire and the brass connection screws on receptacles and switches. The situation was/is so dire that some insurance companies will not cover homes built during the brief aluminum wire era unless it has been re-wired with copper. Not willing to totally surrender the use of aluminum, manufacturers began producing copper-clad aluminum wire for residential use. It, too, eventually proved unsafe and the industry returned to what is today's standard. These days copper is used almost exclusively for 10 AWG and smaller wire (30 A circuits), while 8 AWG and larger is most often multi-conductor aluminum. The service entrance cable to your home is almost certainly aluminum, as is the 50 A (or greater) line to your electric stove, the 40 A (or greater) line to your air conditioner compressor.
Aluminum Wire is likely to increase greatly in popularity in the next few years, the American Society of Agricultural Engineers was told last month. Wartime improvements in manufacture and use of aluminum and the increase in price of copper wire were given as reasons.
Aluminum wire is half as expensive as copper, and its light weight makes it especially desirable for many applications. Its conductivity is lower - it has a specific resistance of approximately 17 as compared with 10.4 for copper - but its lighter weight permits running larger conductors.
Posted December 30, 2014