dimmer question

[anthony001]

today I was installing a dimmer into a metal box and had a thought. now I'm not talking about any leagalities just plain physics. since a dimmer dissapates untransfered energy through the metal plates that surround it. if that is the case would installing one inside a metal box increase its dimmable wattage or does it have to do with the type of metal that surrounds it. just a thought thanks in advance for the replies

 

[celtic]

Re: dimmer question

since a dimmer dissapates untransfered energy through the metal plates that surround it.

HUH?

I thought the plates were heat sinks to dissapate HEAT.
If they were dissapting untransfered energy - wouldn't a single pole switch also have the metal plates?

if that is the case would installing one inside a metal box increase its dimmable wattage or does it have to do with the type of metal that surrounds it. just a thought thanks in advance for the replies

It has to do with watt is causing the heat ~ I?R loss ( I think that is the term/equation I am looking for).
What is causing the heat is the resistor (variable) that "dims" by creating a voltage drop to the lamp .

Here's another explanation:
http://home.howstuffworks.com/dimmer-switch.htm

EDIT: Missed a word, added a pun - did ya' find it?

 

[anthony001]

I think I understand now, the plates are soley for the purpose of dissapating the heat from the resistor. by removing some of the tabs this derates the abilty of the resistor to preform efficently.for some reason I was under the impression that the resistor was actually the heat plate and by removing the tabs you loose the capability to dim the full wattage. is this how it is just curious, thanks.

 

[celtic]

I think I understand now, the plates are soley for the purpose of dissapating the heat from the resistor. by removing some of the tabs this derates the abilty of the resistor to preform efficently.for some reason I was under the impression that the resistor was actually the heat plate and by removing the tabs you loose the capability to dim the full wattage. is this how it is just curious, thanks.

Removing the plates will diminish the dimmer's capacity ~ it's rating in watts.

Here is a link that shows the capacity of dimmer after removing one or both tabs :
http://www.lutron.com/product_technical/ganging.asp
NOTE: Specific to Lutron.

When roughing in lighting controls - be sure to get as much detail from the client on how they want to control the lighting. A 3 gang box to hold 3 1500W dimmers is simply NOT going to work.

 

[LarryFine]

The active device within a modern dimmer is a special type of transistor called a 'triac'. If you know what an SCR is, this is a bi-directional version of the same thing. If not, just trust me. :twisted:

The dimmer circuit delays the turn-on point within each half wave of the voltage sine wave. The delay time is controlled by the knob, and the chopped wave is averaged by the slow response of the bulb filament.