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Old 04-14-2009, 03:52 PM   #1
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Choosing Dimmer Rating for Recessed Ceiling Cans


Ok, here's one that I just can't seem to figure out...

I'm just finishing up the lighting design for my living room remodel. I am installing Halo 6" cans (H7T's) and thus far, the layout is based on 9 fixtures, all to be part of the same circuit. Now, I have already chosen my trims and therein, know the bulbs/wattages that I'll be using. The big question is, as far as sizing the dimmer, does the actual size need to based on my particular application or does it need to be sized according to worst case, i.e. the maximum wattage supported by the limitations of the fixture itself?

To put it another way, while the circuit conductors are more than adequate to handle the worst case/highest wattage lamping, is it a requirement that the dimmer be sized according to maximum wattage as well?

Thanks, peeps!
Jimmy

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Old 04-14-2009, 04:08 PM   #2
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Choosing Dimmer Rating for Recessed Ceiling Cans


Well your using 6" cans and I believe the biggest bulb you can install is a R30 75 watt bulb and you have nine recess so that is 675 watts. The dimmers I use are rated 600 watts and 1000 watts. Even if your not going to put in the maximum wattage bulb its always best to use a dimmer that can handle the maximum wattage that can be imposed onto the dimmer.

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Old 04-14-2009, 04:09 PM   #3
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Choosing Dimmer Rating for Recessed Ceiling Cans


Hey Jimmy,
I would say that if you want your dimmer to last a while, then size it for the worst case. Most of the dimmers that are readily available are 600 W. One thing that may be a drag is that the 1000W dimmers are devices that use two gang openings (even though they are a single device). I may be thinking of a 1200 W dimmer I installed, but if the walls are finished, it could be a bit of a pain reworking the switch box.
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Old 04-14-2009, 04:15 PM   #4
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Choosing Dimmer Rating for Recessed Ceiling Cans


Quote:
Originally Posted by goose134 View Post
Hey Jimmy,
One thing that may be a drag is that the 1000W dimmers are devices that use two gang openings (even though they are a single device). I may be thinking of a 1200 W dimmer I installed, but if the walls are finished, it could be a bit of a pain reworking the switch box.
That is a 1200 wattt dimmer your thinking of. A 1000 watt dimmer is the same size as a 600 watt dimmer
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Old 04-14-2009, 05:06 PM   #5
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Choosing Dimmer Rating for Recessed Ceiling Cans


Goose-Nice to see you back my friend. dSil-thanks for your response as well.

The bulb types and wattages are dictated by the trim used, not simply the can size. I just checked one of my cans (I'm home now) and based on a particular trim, it can be lamped up to 150W. But, that is not my issue since as I mentioned, I already know the lamp ratings that I will be using. And based on the tabs that I'll need to remove from the dimmers (this is a 4-gang box), I have to derate anyway.

This was more a question of code which I don't think has any bearing on my situation. I know that I'm not going to change the trims/lamps after I'm done but since someone in the future could, I didn't know if the dimmer was required to be sized according to the maximum lamp load that could be installed.

Thanks again,
Jimmy
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Last edited by BigJimmy; 04-14-2009 at 05:07 PM. Reason: Mispelled dSil's name. Whoops!
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Old 04-14-2009, 05:50 PM   #6
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Choosing Dimmer Rating for Recessed Ceiling Cans


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Originally Posted by BigJimmy View Post
Goose-Nice to see you back my friend. dSil-thanks for your response as well.

The bulb types and wattages are dictated by the trim used, not simply the can size. I just checked one of my cans (I'm home now) and based on a particular trim, it can be lamped up to 150W. But, that is not my issue since as I mentioned, I already know the lamp ratings that I will be using. And based on the tabs that I'll need to remove from the dimmers (this is a 4-gang box), I have to derate anyway.

This was more a question of code which I don't think has any bearing on my situation. I know that I'm not going to change the trims/lamps after I'm done but since someone in the future could, I didn't know if the dimmer was required to be sized according to the maximum lamp load that could be installed.

Thanks again,
Jimmy

If you look up inside the recess light there will be a sticker that will say what wattage will go with what trim.
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Old 04-14-2009, 10:20 PM   #7
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Choosing Dimmer Rating for Recessed Ceiling Cans


I think you need to size the dimmer for the worst case, just as you would size the circuit for the fact that you could put in 9 150 watt bulbs.
That is how I would do it for a customer, but for my own house, not so sure.
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Old 04-14-2009, 10:26 PM   #8
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I think you need to size the dimmer for the worst case, just as you would size the circuit for the fact that you could put in 9 150 watt bulbs.
That is how I would do it for a customer, but for my own house, not so sure.
I doubt you can put that high of wattage bulb in the can.
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Old 04-14-2009, 10:27 PM   #9
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Choosing Dimmer Rating for Recessed Ceiling Cans


What is the name and model number for the recess lights your using?
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Old 04-14-2009, 10:35 PM   #10
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Choosing Dimmer Rating for Recessed Ceiling Cans


Quote:
Originally Posted by BigJimmy View Post
Goose-Nice to see you back my friend. dSil-thanks for your response as well.

The bulb types and wattages are dictated by the trim used, not simply the can size. I just checked one of my cans (I'm home now) and based on a particular trim, it can be lamped up to 150W. But, that is not my issue since as I mentioned, I already know the lamp ratings that I will be using. And based on the tabs that I'll need to remove from the dimmers (this is a 4-gang box), I have to derate anyway.



Thanks again,
Jimmy
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Old 04-15-2009, 01:32 AM   #11
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Choosing Dimmer Rating for Recessed Ceiling Cans


dSil-

The 150W figure that I quoted was, as JB suggested, straight from the sticker in the can itself (These are Halo H7T's). Maximum lamps size is 150W R40, PAR38 or A21 (I'm not going to bother listing the associated trims). Basically, mine will be lamped at 75W (PAR30) and I'll be using a 1000W dimmer. I guess that, in the absence of any particular code requirement, this will be sufficient for my particular application, as lamped/trimmed, however it will not work if someone ever tries to relamp/trim at 150W. In the end, I see little cause for concern since we plan on owning until the mortgage is paid off!

So in the end, after we sell it, if someone wishes to light up the living room brighter than the surface of the sun, they'll need to upgrade the dimmer from what I've decided to install!

Thanks,
Jimmy
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Old 04-15-2009, 09:24 AM   #12
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Choosing Dimmer Rating for Recessed Ceiling Cans


9 lights x 150w = 1350 max watts
You have to calc the load for the breaker based on the max load possible in the fixture
Seems like you should be doing the same with the switch to meet code
The next person will only replace the dimmer when it melts from overload
I prefer to have less lights on a switch/dimmer
Dimmin by 50% does not reduce the electric used by 50%
Its more like 25%
We had some people do tests on this on a Christmas board
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Old 04-15-2009, 09:45 AM   #13
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Choosing Dimmer Rating for Recessed Ceiling Cans


Quote:
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9 lights x 150w = 1350 max watts
You have to calc the load for the breaker based on the max load possible in the fixture
Dave-

I am not lamping/trimming for that amount (my application is 9x75W=675W or 5.5A calculated at 120V nom.). The branch circuit rating is well above the expected load for the circuit (there is approximately another 3A max on this circuit, but not on the dimmer). Even at 9x150W, the total load will not exceed the branch circuit rating. The question is the dimmer rating.

Quote:
Seems like you should be doing the same with the switch to meet code.
This is the real question however I cannot find a reference.

Quote:
The next person will only replace the dimmer when it melts from overload.
It would be overloaded if the person decided to change all the trims and lamps (why anyone, excluding perhaps a mole, would want 1350W of light for this room would be beyond me). However, I would assume that at that point, they would need to verify that the dimmer was compatible. I have a decorative table lamp that is rated for a 40W max bulb however, the socket accepts standard edison-base bulbs. So there is nothing stopping me from loading it with a 150W incandescent and possibly setting it on fire.
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Old 04-15-2009, 10:42 AM   #14
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I was referring to the Max load, which is what I have always calculated any dimmer installation. Since by load calc you need to go with the highest value to meet code I have to assume code wants the same for a switch/dimmer
I have a lighting circvuit loaded to 1650w by load calc
But with CFLs in place I am only using about 1100 watts
75x9 = 675watts - but that will put out some heat
13w CFL x9 = 117w
But the CFL dimmable bulbs are expensive

But 150w with 9 lights would be a football stadium

The H7T is rated for MAX 100w bulb
The H7 RT is rated for 150w
http://www.cooperlighting.com/specfi...nfopdf/H7T.pdf

Unless someone put the wrong sticker on sounds like you have the RT

I use the 6" Halo cans that are rated for 75w max
But really, how many people read the cans?
Many average HO will just stick a bulb in there
I know when I was 1st renting Apts I never read the inside of a can
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Old 04-15-2009, 10:51 AM   #15
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Choosing Dimmer Rating for Recessed Ceiling Cans


Quote:
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The H7T is rated for MAX 100w bulb
The H7 RT is rated for 150w
http://www.cooperlighting.com/specfi...nfopdf/H7T.pdf
Dave-

Scroll down and look at some of the different trims that are available for the H7T. Since the trim dictates lamp/wattage, you'll notice that there are three different 150W lamps that can be used depending on trim selection. These are indeed H7T's and if I remember correctly, the sticker even indicates H7T (it is noted elsewhere on the fixture, too).

Jimmy

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