Ceiling Fire Rating - Boxes or Not

[Duncan8943]

I have to install several 4' surface mount fluorescent light fixtures. They will be mounting to the drywall in a vaulted ceiling, as well as, drywall on a horizontal ceiling. I had planned on using octagon boxes for each light with a flat mud ring to be able to maintain the fire rating. I think that I could also use "fire caulk" to seal between the mc cable and the drywall ceiling then use a connector to the light fixture. To me this would be almost impossible to guarantee and could be quite messy. Any ideas on which way is the best or a better way of doing this? Thanks.

 

[Ponchik]

Will the boxes be recessed or surface mounted? Will the wiring method be behind the sheet rock or surface mounted?

Is there another living space above that ceiling? Is that ceiling fire rated?

 

[Sierrasparky]

more info is needed.
as long as you use boxes listed for the purpose and do not exceed the amount of penetration per area of space you are ok.
Also remember in a rated assembly you cannot hang a fixure directly from the drywall itself.

 

[hurk27]

I have to install several 4' surface mount fluorescent light fixtures. They will be mounting to the drywall in a vaulted ceiling, as well as, drywall on a horizontal ceiling. I had planned on using octagon boxes for each light with a flat mud ring to be able to maintain the fire rating. I think that I could also use "fire caulk" to seal between the mc cable and the drywall ceiling then use a connector to the light fixture. To me this would be almost impossible to guarantee and could be quite messy. Any ideas on which way is the best or a better way of doing this? Thanks.

Theres also a company who makes a UL listed putty pad that you put into the back of your boxes that when the heat from a fire hits them they expand and seal off the box to give you a fire rated seal, I can remember who makes them but I'll see if I can find them.

Bing this: putty pads rated for 3hr assembly it will pull up all kinds of links on them for various sizes and purpose, or just click on this link:
http://www.bing.com/search?q=putty+...RM=QBRE&cvid=362da3f0b60b4d129fbf583e487faec1

Heres a PDF to the 3M stuff I'm thinking about:

http://multimedia.3m.com/mws/mediaw...TSeSSSSSS--&fn=3M FB MPPpls StixPDS4620-2.pdf

 

[mgookin]

We always made EC's five-side those boxes. I suggest you contact whoever is going to do your inspections.