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annular space around rated light fixtures & diffusers in rated ceiling

syarn

syarn

Silver Member
Joined
Jan 20, 2010
Messages
251
Location
Philadelphia, Pennsylvania, United States
gypsum wallboard ceiling 1 hour fire rated horizontal shaftwall 4" C-H stud w/1" sheetrock & 5/8" sheetrock.

four fire-rated downlights and a fire-rated supply diffuser in this ceiling.

the annular space between the edges of the downlights & the diffuser - is there a code section or UL # that specs how this "gap" is filled to maintain the fire rating?
 
I don't know which code cycle you are under but, Did you try the 2012 IBC

714.4.1.2 Membrane penetrations.

Penetrations of membranes that are part of a horizontal assembly shall comply with Section 714.4.1.1.1 or 714.4.1.1.2. Where floor/ceiling assemblies are required to have a fire-resistance rating, recessed fixtures shall be installed such that the required fire resistance will not be reduced.

Exceptions:

4. Membrane penetrations by listed electrical boxes of any material, provided such boxes have been tested for use in fire-resistance-rated assemblies and are installed in accordance with the instructions included in the listing. The annular space between the ceiling membrane and the box shall not exceed 1/8 inch (3.2 mm) unless listed otherwise..
 
syarn said:
It's not a membrane penetration it will be a "through" penetration for each light fixture.....
Click to expand...
Okay, per listing:

714.4.1.1 Through penetrations.

Through penetrations of fire-resistance-rated horizontal assemblies shall comply with Section 714.4.1.1.1 or 714.4.1.1.2.

3. Penetrations by listed electrical boxes of any material, provided such boxes have been tested for use in fire-resistance-rated assemblies and installed in accordance with the instructions included in the listing.
 
syarn said:
It's not a membrane penetration it will be a "through" penetration for each light fixture.....
Click to expand...
Huh????

I look up at the cieling and see the recessed light ,,,

And then I go to the floor above, directly over said recessed light and I see the top of the recessed light sticking out of the floor???
 
CDA it's a new "false" ceiling (basically an elevator shaft wall turned on it's side) so it's below the actually structural ceiling/floor.

The new ceiling is about 5" thick and the new recessed light fixtures are about 9" deep...

trying to get more detailed info from phillips lightolier FD2IC6V2632U & the diffuser is a titus FR-PAS-FR
 
syarn; per your image, it appears the fire caulking is required at "red" juncture between fixture and ceiling board UNLESS the fixture listing for installation in fire rated assemblies shows otherwise.

If the fixture listing doesn't show the exact assembly being used, then a fixture listed for the actual fire assembly must be used. I poked around the phillips and titus websites, did not find anything for a shaft wall type assembly. Usually fixtures are membrane penetration only. The Artichoke or Engineer appears to have a tough design problem.
 
syarn said:
CDA yes but it's full through penetration NOT a membrane...so per attached image it's the "annular space" between the ceiling material and the fixture/diffuser (in red) should that be fire caulked?
Click to expand...
You do not what I would call a through penetration , in my mind, it goes through the Entire assembly.

What I see you have is just thorough the ceiling or one portion of the assembly

For that install per manufacture.

I saw one that required fire stop material and one just snap in place
 
syarn said:
Cda that's a good point does the topside annular space of the horizontal ceiling have to be sealed as well....???? because the diffuser & the lights do penetrate through the entire ceiling...
Click to expand...
Check the manufacture install instructions

I would say normally NO

as seen in the examples, I take the red stuff to be fire stop material

http://www.archtoolbox.com/materials-systems/thermal-moisture-protection/through-penetration-firestop-and-fire-resistive-joint-systems.html
 
The flange around the grill covers the annular space and should be part of the listed assembly. Most fire damper assemblies require 2" X 2" angles around the sleeve and prohibit the installation of expandable fire stop materials as it may interfere with the operation of the damper.

Follow the manufactures installation instructions. They will specify the maximum annular space allowed
 
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