On Dec 31, 2015, at 2:47 PM, Geoffrey Oltmans
<oltmansg at gmail.com> wrote:
On Thu, Dec 31, 2015 at 12:17 PM, Fred Cisin <cisin at xenosoft.com> wrote:
Almost half a century ago, there were attempts to use aluminium instead of
copper for house wiring. It did not go well.
No, it didn't! We looked at several old houses back in 2012 before we
bought the house we're in now. Several of these houses were from the late
60's/early 70's and that concern was forefront in my mind with them. They
still sell special outlets and switches compatible with aluminum wiring in
the hardware stores.
I haven't see aluminum-rated devices in hardware stores in many years. Be careful:
typically they will be labeled either as "copper only" or as "CU/AL".
But that doesn't mean "copper or aluminum" -- it means you're allowed to
user copper-clad aluminum. That's a hack type of wire that was adopted for a while
after the plain aluminum was discovered to be a Very Bad Idea. It's not quite as bad
but there is really no justification for its existence, and indeed it is no longer the
current practice. Copper-clad aluminum can be used with copper without much trouble, but
the wire is thicker and it breaks more easily.
Plain aluminum must only be used with devices specifically rated for plain aluminum. You
may need to use anti-corrosion paste. "devices" includes wire nuts -- standard
copper-only wire nuts are not approved for use with aluminum wire.
My experience is that aluminum-rated devices and wire nuts can only be found at electric
supply specialists, and they are vastly more expensive than regular devices. When I used
up my box of aluminum-rated wire nuts (standard hardware store item in 1980) I found that
trying to buy them now (2005 or so) was possible but I'd have to pay a dollar EACH, if
The only place where you're likely still to find aluminum-rated devices without a lot
of effort is in high current stuff -- main breakers, 100 amp branch breakers, that sort of
thing -- because aluminum cable is still used there at least by some people. Personally,
I never use it; 2 gauge copper may cost more but I prefer the peace of mind it delivers.