Dimmer switch heat?

I know dimmer switches run warmer than regular ones, but how much so? Hooked a brand new one ($15) up to our dining room light. On low it's just warm. On full (light tottally on) it's pretty hot (the metal frame) - too hot to put your finger against for more than a few seconds. I haven't put on the plastic cover trim yet.
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It's normal. Your standard dimmer is 600 watts if it's in a box by itself. If it's ganged with other switches or dimmers it must be derated as per its instructions. the metal faceplate of the dimmer is the heat sink and it will get hot. Nothing to worry about as long as you didn't overload the device.

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RBM wrote: It's normal. Your standard dimmer is 600 watts if it's in a box by itself. If it's ganged with other switches or dimmers it must be derated as per its instructions. the metal faceplate of the dimmer is the heat sink and it will get hot. Nothing to worry about as long as you didn't overload the device.
======= What does the 600w power rating of the switch have to do with how much warmer or how safe a dimmer switch is compared to a standard switch?
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Gideon wrote:

Higher rated switches usually use heat dissipation designs and they may have heavier duty parts that have less resistance, hence less heat.
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Joseph Meehan

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They use a triac to shut off the current for part of the sine-wave cycle when dimming,and thus only conduct and dissipate a small amount of heat when the light is low.At full intensity,the triac is on through more of the cycle and has to conduct more current,and it's ON voltage drop means that it dissipates more heat.
Your dimmer may last longer if you use a metal plate behind the plastic cover to help conduct away more heat.
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Jim Yanik
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jeffc wrote:

Hi, They come in at different Wattage rating. Count the lights in the chandelier and see if your dimmer is within spec. I had to use heavier one for my dining room and living room light fixtures. I'd think that's too hot. Tony
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I think that it is too hot, also. A good rule of thumb is that you should be able to touch it for any length of time. I don't like things that are too hot to touch to be installed inside a wall. in a metal box or plastic or plastic one.
Charlie
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Oh good point. There are a bunch of lights in that chandelier.
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Why do you need a dimmer in a chandelier? The old fashioned trick is to slightly unscrew a few of the bulbs (leaving them in place, but not allowing them to make contact). In times of expensive energy (esp mid 1970s) we did this on chandelier & sconces.
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Golly, I can just imagine how much fun that would be to move the kitchen table, get out a ladder, and screw in or unscrew some bulbs every time I wanted to change the light intensity.
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Nah, just stand on the kitchen table and do it from there.
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Its my experience that the switch runs hotter when "dimming"..creating heat instead of light by running the current thru more of the resistance (rheostat) material..When the light(s) are full on, there should be a lot less heat, if any so I'd say there is something wrong.

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The pot should *not* be generating heat since it is in the low power or gate part of the circuit. An RC time constant generates a pulse that fires the gate on the triac causing a chopped sine wave to appear across the load....as the resistance decreases the time decreases the the bulb gets dimmer, since the *on* time of the triac has decreased. The heat is generated by the triac. The more it conducts (on time) the warmer it will be. It sounds like the dimmer switch is just poorly designed. If the dimmer is REALLY poorly designed it will not even have a choke attached and you should hear an audible buzzing .... Advice to the OP....Buy a higher wattage good quality dimmer and toss the charcoal starter......Ross
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heat
The rheostat as you call it is not the problem. It only has a very small ammount of current in it. The SCR or triac (solid state device) is where the heat is being generated. There is a small voltage drop in this device. Around 1 volt. This times the ammount of time the deivice is conducting and the ammount of current being used by the lights determin the ammount of heat. The longer the device is on (out of a 60 hz switching rate) the more heat will be generated.
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