March 1948 Radio-Craft
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Craft,
published 1929 - 1953. All copyrights are hereby acknowledged.
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.
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
Posted December 30, 2014