dimmer switch

[tolbiny]

Is it unsafe to install a dimmer switch on the average dining room ceiling light if the house is older and has aluminum wiring?

[RBM]

No, just be sure the terminals on the dimmer are listed for aluminum, CU-AL

[Pete C.]

...And apply anti-ox compound to the connections and retighten them after a month or so. Then they should be ok.

Pete C.

[RayV]

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

[mm]

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.

[Zootal]

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.

[RayV]

I stand corrected:

sort of: 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.