Two dimmers on the same circuit

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Old 04-19-10, 02:38 PM
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Two dimmers on the same circuit

Hi guys,

It's been a while since my last post. I searched high and low for a thread on this and found nothing, so my apologies if this has been covered.

If a dimmer switch is rated at 600 W, does that mean that it's always pulling 5 amps (600/120), whether the fixture it controls is on or off? For example, if I have four 60 W bulbs in a fixture controlled by a 600 W dimmer, is the load 2 amps (240/120), as it would be with a standard switch (assuming nothing else is active on the circuit), or 5 amps (600/120)?

I ask because I'd like to replace two standard switches, on the same circuit, with 600 W dimmers, but if they're both always pulling 5 amps on a 15-amp circuit, that leaves only 5 amps on that circuit, if I understand properly. I'm not sure if that's even a problem, but you never know when something heavy duty might get plugged into a kitchen outlet.

Thanks!
 
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Old 04-19-10, 02:45 PM
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The ratings on dimmers are the maximum watts of bulbs they can control. For example a 600W dimmer can control up to ten 60W bulbs. The amount of power used by a dimmer at 100% brightness is equal to a standard toggle switch switched ON. The power consumed drops as you decrease the brightness. The dimmer consumes no power when off.

Note that if you put multiple dimmers in the same box, the maximum wattage drops. This is called "derating" and is usually covered by the installation instructions. For example a single dimmer may be able to support 600W, but if you put two in the same box they each drop to 400W. (Exact values depend on manufacturer specs).
 
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Old 04-19-10, 02:47 PM
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Great! Thanks for your help Ben!
 
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Old 04-19-10, 08:52 PM
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Originally Posted by ibpooks View Post
Note that if you put multiple dimmers in the same box, the maximum wattage drops. This is called "derating" and is usually covered by the installation instructions. For example a single dimmer may be able to support 600W, but if you put two in the same box they each drop to 400W. (Exact values depend on manufacturer specs).
One thing I want to add is this is because of the heat the dimmers create.
 
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Old 04-19-10, 09:40 PM
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There one trick I always do with mulit dimmer switch boxes if you have more than two dimmers in there my simple trick is get metal switch cover I know they do come in colour verison as well so that will help a bit they will act like heat sink to remove much heat as possbile. { this is true with very high wattage dimmers < above 1000 watts > }

{ Yeah you still have to follow the manufacter instruction for the derating if you remove the fins if have it and two or more dimmers the same thing it will derated the wattage }

Merci,Marc
 
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Old 04-20-10, 12:57 AM
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If you use a multi-gang box and leave a blank space between two dimmers you will not have to remove any fins and therefore you can retain the original wattage specifications on the dimmers.
 
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