Probably is unsafe if the dimmer has copper wire leads that have to be
wire nutted to the Aluminum wire. Dimmers create resistance which
raise temperatures which cause aluminum wire to fail. Make sure
whatever you install is rated for Aluminum wire.
Read up and change the batteries in your smoke detectors
Seems to me it would be "Dimmers create resistance which cause less
current to flow through aluminum wires so they don't get so hot as
they would if there were no dimmer."
What about light bulbs? Even without dimmers, light bulbs create
resistance. Do they cause aluminum wire to fail? Bulbs can get a lot
hotter than a non-malfunctioning dimmer.
Maybe I didn't understand you.
Dimmers are usually triacs, and don't generate much heat. Certainly not
enough to cause problems with aluminum wiring. I lived in a house with
aluminum wiring. I made sure all receptacles and switches were rated for Al,
was carefull not to let copper wire contact Al, and never had problems.
So - if the dimmer is rated for Al wire, then it's not likely to cause
problems with Al wiring. As for using it with a ceiling fan, it's usually
considered a bad idea. Dimmers are not rheostats or potentiometers. They are
usually triacs. They do not gently reduce the voltage, they delay turning on
during part of the a/c cycle so the average voltage is reduced. The output
would be rough on many devices, even light bulbs. Supposedly this can damage
the ceiling fan, but I've not actually tried it.
I stand corrected:
The older dimmers generated heat from the rheostat the newer ones
generate heat from the electronics.
Heat + aluminum wiring = bad thing
It doesn't matter if the heat is generated in the wire or in the
internal electronics of the switch it will still be trapped in the box
along with the aluminum wire. The constant expansion & contraction of
the aluminum wire is what causes the connections to fail. Also keep in
mind that the cheap builder that used the aluminum wire probably also
used cheap/small boxes that make the problem worse.
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