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Discussion Starter · #1 ·
quick question...has anyone had any problems with the backer boxes getting too hot and tripping the can light heat protection circuitry?


my joists are 24" oc so i was planning on making OSB + cement board backer boxes for 6" new construction cans. that would give me boxes approx 12" x 12" x 22.5". surely that's big enough to dissipate the heat, right? and then put a little insulation in there so the box doesn't resonate.


any other thoughts?


thanks as always!
 

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I don't have any data to suggest you will be fine but my gut says it shouldn't be a problem. You also need to consider whether you will be operating the lights with the full bulb wattage at full power for extended periods of time. That would be pretty rare for a theater.


I assume you are planning to get IC cans, I would also grab Air tight cans as they are made "not to breathe"
 

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Discussion Starter · #4 ·
definitely getting air tight IC cans.


i looked at the soundproofingcompany.com site and the dimensions of their box were smaller, but it was for 4" cans. do 4" cans use the same bulbs as 6"?


and when i called the soundproofing company, the "other guy" (not ted) couldn't really give me any info...he said my electrician would have to say how big the boxes have to be, and my electrician has no idea.
 

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if you Google Fire boxes for recessed lighting you get a lot of links for commercial products or site built versions. The pictures should give you and idea of size and from my search there doesn't appear to be a minimum size standard.









 

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I have PAR20 50 watt cans in back boxes. I have had -ONE- heat trip off in two years, with the lights often seeing long hours of constant use at full brightness. The glass trim rings are open on the bottom so they might allow some heat out. Bulb life seems a little suspect.


My fixtures are Bazz 100 retrofit style 4" cans, and while I don't have the exact dimensions of the back boxes, I have some marked cutting notes and dimensions that show up on the first layer of drywall that give some idea of scale. MY floor joists are an unusual 7" of depth.


I planned on using some insulation between the metal box and the back box, but skipped it. If I ever build another theater, I'll keep the double wall construction (with GG) and eliminate the metal boxes (which was most of the cost). I'd use cement backer board as the inner surface, instead of the two MDF layers I used.



 

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BTW, one problem with those sliding arms in the picture Big posted, is they could rattle. They need to be crimped and taped. The fixture's electrical box should also get a few wraps of electrican's tape.
 

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Discussion Starter · #8 ·
thanks for the input, especially pictures. one other question...


- walls are dd/gg, and are decoupled with staggered studs

- ceiling is dd/gg, but is NOT decoupled

- floor (this is 2nd floor) is double advantech with gg (not directly above bedrooms, and celing below insulated)


so the question is, is the lack of decoupling such a flaw that these backer boxes are a waste of time?
 

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Discussion Starter · #10 ·

Quote:
Originally Posted by BIGmouthinDC /forum/post/19601877


What is above this room?

attic over a little part of it, but mostly just open rafters. kids bedrooms are also on 2nd floor so i'm afraid of the sound leakage even with almost a foot of blown insulation.
 

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I suspect that structural vibration from the solidly connected walls and ceiling will be the biggest source of sound in the bedrooms. Having said that I would stick some boxes over the lights anyway since you have easy access.
 

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Quote:
Originally Posted by BIGmouthinDC /forum/post/19602719


I suspect that structural vibration from the solidly connected walls and ceiling will be the biggest source of sound in the bedrooms. Having said that I would stick some boxes over the lights anyway since you have easy access.

I agree
 

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Discussion Starter · #13 ·
thanks for all the input! guess i'm building some boxes...
 
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