full power dissipation occurs when the triac is full on (full brightness).
The triac has only 2 states (on and off) and dimming is controlled by where
in the AC cycle it turns on. Compare the wattages of the bulbs on the 3
dimmers, the warmer dimmer should have the higher wattage bulb.

"HA HA Budys Here" wrote in message
...
From: indago

031108 0129 - Blake Patterson wrote:

I have 3 dimmers in my house that are the same model dimmer. Have them
controlling ceiling lights. Two give of very minor warmth generally
during operation, while one gives off so much heat that the screws
holding in the face plate are almost too hot to touch.

Is this likely a bad switch? Just get a new one? Worrisome as it's
housed in a plastic box, not metal.

Thanks.



bp

The Triac -- the semiconductor device in the dimmer that does all the
work
-- is fastened to the metal strap of the dimmer for heat sink function.
It
is obvious that the dimmer is at its maximum with the lights on full
bright.
If you turn the lights on the dimmer on dim, the heat should diminish.

Isn't that backwards? When the lights are full bright, the dimmer is doing
nothing and the triac should be completely bypassed. At the very least,
it's
doing no work whatsoever.

When dimmed, the dimmer the lights, and the higher the total wattage, the
more
work the triac is doing and therefore, the hotter it gets.

Maybe you should consider getting a new dimmer with a higher wattage
rating.