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Dimmer danger?


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I'm concerned about this dimmer I've got in the kitchen. It's on one end of a 3-gang box, derated to 800w. It runs 7 75w halogen can lights (1 currently burned out). There are two other dimmers in the same box that are both generally in use when this one is. Their loads are about 200w each.

After a few hours of running all 3 dimmers at 100%, the problem dimmer's heat sink is very warm. Not uncomfortably hot to the touch, but very warm. The other two dimmer's heat sinks get luke warm. The problem is, when it is hot like this, it doesn't ramp anymore. The other two still do. For instance, if it's on, I'll tap to turn off, the ramp time will pass, but it will then suddenly turn off without dimming the lights at all. Tonight I played with it a little more. Eventually it started to dim, but it would flicker quickly to 100% and back as it ramped. This all has me concerned. I don't need a Control4 fire. Thoughts?

While we are at it, I've got another dimmer that's at the end of a 4-gang box, derated to 800w. There is a keypad next to it, then a dimmer (100w load) then a switch. Typically, this dimmer is the only one in use at any given time. It runs 9 of these 75w cans. At 100% for a few hours, this heat sink gets very hot, like uncomfortable to the touch-hot. Even the buttons are warm. I haven't noticed that it stops dimming though, maybe I should test more. Should I be concerned?

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When you put 3 or more dimmers in a box they all get derated to 600w. This is true even for the dimmers on the ends that only have the tabs broken off on only one side.

This is documented in the install instruction included with the dimmer and is under the heading "Multi-Gang Installations".

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I have a dimmer on one end of a three gang box (all three are Control4 dimmers) and it has been getting hot like that for 4+ years. It controls some of the can lights in my eves. There are 10 65 watt can lights on that dimmer, and it's usually dimmed to about 35% (done automatically).

Actually, let me double check that.

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My experience has been that you have to take Control4's de-rated wattage and then de-rate it by another 30% or so. If you run them near their rated / de-rated limit they work for a month or two, but eventually they begin to fail. I have had them lose their ability to ramp but my most common symptom is that they being to randomly flash. Like any dimmer, Control4 or not, the fins will often become very warm. I would agree that decreasing the total load on the dimmer is your best bet and LEDs are an excellent way to do that.

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  • 2 years later...

Re opening as I have a question since I am going to have 11 cans on 1 dimmer in a 2 gang box.

So the max rating for this setup would be, 600W MAX for all 11 cans?

I plan to run a 65W light bulb however only have it at 80% dimming all the time. If my math is correct this would be 572W on the dimmer. From the people with experience, on mulit gang C4 dimmer switches, is this a bad idea? Or is it OK as long as I don't run the light for days on end...

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I wouldn't do it.

Putting the dimmer close to it's max will cause additional heat, which can prematurely ruin the dimmer, and guaranteeing that it stays at only 80% (maybe someone later will come change that setting) to keep it below the max IMHO is a bad idea.

Unfortunately, it's difficult to break it out to multiple dimmers, but fortunately, as dimmable LEDs come on board and get cheaper, it may not be an issue with one dimmer at some point in the next few years.

RyanE

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Also, having it run at 85% or whatever doesn't in any way decrease the actual wattage rating of the load.

A secondary option, though not always pretty, is to put a lutron booster in-between the loads and the dimmer

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2 gang you're good for 800 W. No problems with your 11 cans, especially at 80%.

Nope - official rating is 600 watt once installed in ANY multigang.

Yes I'm aware this USED to be different in writing - but been this way for a long while now.

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So based on this chatter, you would not do it with a 65 Watt bulb? Or you would not do it because I could burn the dimmer out sooner then not...

If I was to go to a 50 Watt bulb, would you do it then? I would be close to 100 percent dimming and right over 600 Watts...

Thanks for the answers so far.

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With all this chat, I am looking to go to a LED setup. Can anyone recommend a LED that will work with DIM-1 dimmers? I will have a 11 lights, so I guess I should be good with dimming as 11 is a lot of lights...

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With all this chat, I am looking to go to a LED setup. Can anyone recommend a LED that will work with DIM-1 dimmers? I will have a 11 lights, so I guess I should be good with dimming as 11 is a lot of lights...

I hear good things about Cree based units

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2 gang you're good for 800 W. No problems with your 11 cans' date=' especially at 80%.[/quote']

Nope - official rating is 600 watt once installed in ANY multigang.

Yes I'm aware this USED to be different in writing - but been this way for a long while now.

Cy, where did you hear this?

im not aware of this change, not to mention what if the dimmer shares a 2 gang box with a keypad, the derating makes no sense to me, 400 watt loss next to a keypad

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2 gang you're good for 800 W. No problems with your 11 cans' date=' especially at 80%.[/quote']

Nope - official rating is 600 watt once installed in ANY multigang.

Yes I'm aware this USED to be different in writing - but been this way for a long while now.

Cy, where did you hear this?

im not aware of this change, not to mention what if the dimmer shares a 2 gang box with a keypad, the derating makes no sense to me, 400 watt loss next to a keypad

Looks like they changed it again ... I have three different install/spec manuals stored, oldest was 1000, 200 for each TAB broken off, next was 600 when in any multi-gang scenario tabs or not, new info on "legacy lighting" again states 1000 - 800 - 600 now sole based on single - double - 3+ gang....

As for why keypad - that would be because the keypad takes up as much airspace in the diminishing relative size of the box...

All of it is rather debatable of course - the original rating of a 1000w would logically be based on the inter capabilities, not how well it dissipates heat, so if you have other ways of dissipating heat (I for instance use slightly oversized stainless steel face plates which very noticeably diminished the heat on my black dimmers/devices once installed), it again would logically become a 1000w.....

But yeah current docs again say 1000 - 800 - 600, no mention of that being dimmers only etc.

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Thanks guys for the information. So what I am hearing is I should be fine...Or if the dimmer burns out it is because I cooked it. :)

Either way I will give it a whirl, prob get a bigger 2 gang box to hold the units so there is some more space for cooling...And my plates are stainless steal so they should take some heat.

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  • 3 years later...

Hoping to revive this thread. My entire home was retrofitted with C4 lighting - I can't tell you how many Adaptive Phase Dimmers I have burned through when well within the operating specifications.

I agree with J4C4 that I have learned over time to always derate the C4 max load another 30% below what it quotes. Otherwise I had loads in the 500 Watt area blowing out after a month of two of continued use. (Usually 4" cooper or halo MR 16 high hats with 65 Watt Bulbs). And if I need to control more wattage than it can handle - C4 recommends the adaptive phase Lutron Booster (that way you cant blow it up no matter the load type you put on it). I have these all over my home - it brings each zone's total wattage available up to 2,000 AND takes the work off of the dimmer. Only downside is they run $300+ a pop...

Anyone else have a crappy experience with the C4 Adaptive Phase Dimmers? 

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From the range of responses I gather I was not clear enough in my original post: I've never had dimmers installed against manufacturers specs / recommendations. Rather, I have found the derating suggested by the manufacturer not to be in line with what Adaptive Phase Dimmer can really do on high voltage loads.

It seems that most people have had a pretty good experience with the recommended 600W maximum, but that a select few have seen the same results as me IE staying well below 600W is better long term practice practice and that Lutron Boosters help avoid splitting a load onto multiple dimmers.

Knowitall - can you explain further the meaning of 'bulb list' and where to find it so that I can confirm my integrators are following this recommendation? Thank you.

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25 minutes ago, Lone Pine Farmhouse said:

@knowitall Found it - thank you.

If you're using incandescent bulbs, you might want to try the Forward Phase dimmer. It's rated at 1000 watts in a single gang configuration. Honestly, this is the max you'll find in a smart dimmer. Anything above that requires a booster, which you already know about.

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