Charlie said:
My folks had an old mobile home that apparently had been made with
aluminum wiring. She complained that half of one side of the house
had no power, so I started testing. Came to one outlet that still had
power, and went back one, and opened it up. It was black inside. It
had come loose and burned, and no one had noticed! I replaced it with
a new Al rated outlet, and started testing and replacing all the
others...
Charlie
There were enough problems with aluminum wiring used for 15 & 20A branch
circuits (used about 1965-1973) that UL pulled all the listings and
issued new standards - that includes CO/ALR ratings for receptacles and
switches.
The CPSC (U.S. consumer product safety commission) appeared to be headed
for a recall of #12 & #10 aluminum wire, which would have been
enormously expensive. In the inevitable court case, wire was deemed to
not be a consumer product. A lot of testing of aluminum connections had
been done for the CPSC by an independent lab. Recommendations, from an
engineer involved in the testing, are at:
http://www.kinginnovation.com/pdfs/ReducingFire070706.pdf
(The recommendations were around long before the manufacturer came out
with a product.)
One major problem is that a thin insulating oxide layer forms very
rapidly on an aluminum surface. Common to most of the recommended fixes
is to put an antioxide paste (which just keeps oxygen away from the
surface) on the wire and abrade it to remove the oxide. This is done,
for instance, before installing a CO/ALR receptacle.
The author does not like the only wire nuts that are currently UL listed
for aluminum. Recommended are:
http://www.kinginnovation.com/products/electrical-products/alumiconn/
which are also UL listed. They have a screw that digs into the wire
through the oxide. I think it is the same style of splice they use in
the UK.