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View Full Version : Capacity of dimmer switches and how many can go in a 3 gang box?


larry5275
Jan 26, 2009, 08:37 AM
I am lighting my basement with a good number of canned lights. I'm trying to determine how many lights can be put on one dimmer and how many dimmers can go in a 3 gang box.

If I have read correctly I can get up to 1000 watt dimmers and I should only load that up to 80%. I have no idea how many dimmers can go in a 3 gang box. I know there are heat considerations to account for.

Any input would be appreciated! Thanks!

WallyHelps
Jan 27, 2009, 06:30 AM
Well, if you load a dimmer to 80% (800 watts) that would allow for 800/65 = 12 typical 65 watt floods. I would think for sure you could put two dimmers in a 3-gang box, but I am not sure what the NEC says.

Unless you have a HUGE basement, two dozen lights ought to be enough.

That's my 2 cents anyway,
WallyH

ceilingfanrepair
Jan 27, 2009, 11:43 AM
You can get dimmers that are 1500 watts, 2000 watts, etc, but they are special order and pretty expensive.

I always plan for the highest wattage bulb the can lights are rated for, because you don't know what future owners will put in there.

KISS
Jan 27, 2009, 11:59 AM
In wall dimmers when placed in multi-gang boxes generally are not rated for full capacity because you have to remove either the left side, right side or both sides the heat sink some to make them fit into the box.

ceilingfanrepair
Jan 27, 2009, 12:17 PM
Good point.

WallyHelps
Jan 27, 2009, 12:35 PM
In wall dimmers when placed in multi-gang boxes generally are not rated for full capacity because you have to remove either the left side, right side or both sides the heat sink some to make them fit into the box.
I found this chart here (http://resi.lutron.com/Portals/3/Product/Install/Local%20Dimmers%20and%20Switches/043-236a.pdf) at Lutron's website. Even if you removed both sides on all 3 switches, it looks like you could go with 3 de-rated to 700W apiece or 2100W. This would allow up to 2100/65 or 32 cans. Technically, you could probably only remove (for example) the right side from the two left switches and leave the rightmost switch alone for (900+900+1000 = 2800W), which would give you another 10 lights, but geeez how many do you really need?? :D

Hope we've helped!
WallyH

Stratmando
Jan 28, 2009, 03:38 PM
The most dimmers in a 3 gang without going Electronic is 3 Dual slide dimmers.
A total of 6 controllable sets of lights, How many lights in basement, and to each dimmer?