Mc cable in 2hour fire rated ceiling

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djtazjr

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I am recently installing IC type recessed lights in a 2 hour rated ceiling. What are the requirements for running MC cable through this ceiling? I know this ceiling isnt plenum rated but, does the code require the MC cable to be fire rated?

Further information about this place is that it is an apartment in a commercial building. The ceiling has 2 layers of 5/8 gypsum board and bears wool insulation.

Please help me have a clue? I can not finding any requirements in the NEC, or even what kind class this is under.
 
ryan_618

ryan_618

Senior Member
Location
Salt Lake City, Utah
Re: Mc cable in 2hour fire rated ceiling

You'll have to build a box around the cans that is equal to the rating of the membrane you are penetrating...(2 layers of 5/8 type x with the corners and joints either taped or fire caulked with a caulk meeting the ASTM E119 protocol).

As far as the MC goes, it is listed for penetrations through a rated assembly, so you will just need to fire caulk the annular space around the MC cable.
 
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djtazjr

Member
Re: Mc cable in 2hour fire rated ceiling

Ok? So Type IC recessed cans are not fire rated for 2 hour burn? But if the mc cable is listed it would be blue, I can not remember what it is called. The only thing I can not realize is the fact about the MC cable running through the ceiling from light to light, and through the rest of the ceiling for my branch circuits?

The Mc Cable would have to be caulk when I penetrate the box that I build around the recessed can correct? Which building code if that by the why Ryan. I appreciate the help!
 
ryan_618

ryan_618

Senior Member
Location
Salt Lake City, Utah
Re: Mc cable in 2hour fire rated ceiling

The intent of a rated ceiling is to isolate two areas from each other. With that in mind, the MC cable IN the ceiling is not the problem.

Take a look at the tag that comes on the roll of MC cable and you will find that it is rated for penetrations (at least, all of the MC I have seen is).


This is from the 2000 International Building Code. I am home right now so I don't have it in front of me, but if you would like, I can tell you the section number tommorrow morning.

And you are welcome my friend.
 
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djtazjr

Member
Re: Mc cable in 2hour fire rated ceiling

Yes Ryan I would appreciated any help you give my. And thanks to the both of you. I will have to check with local codes also.

Thanks again. :D
 
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rickg

Member
Location
Rhode Island
Re: Mc cable in 2hour fire rated ceiling

Pardon my ignorance, is romex allowed to connect to these recess cans? The wire compartments are above the ceiling.
Rick
 
ryan_618

ryan_618

Senior Member
Location
Salt Lake City, Utah
Re: Mc cable in 2hour fire rated ceiling

Section 711.3.2 of the 2000 IBC states that:

Membrane penetrtations shall comply with section 711.3.1. Where walls walls and partitions are required to have a minimum 1-hour fire resistance rating, recessed lighting fixtures shall be installed such that the required fire resistance will not be reduced.

To me, that states that the aforementioned box must be built.

Rick: I wish I had an answer for you on the romex question. I think it is ok to penetrate with NM as long as the annular spaced is sealed with an intumescant caulking that complies with the ASTM E119, but I'm not positive.
 
roger

roger

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Retired Electrician
Re: Mc cable in 2hour fire rated ceiling

Ryan is right that the MC is listed for use in "through penetrations".

When the fixtures are "boxed in" it must be approve by the AHJ or a UL assembly listed in the Fire Resistance Directory, or on UL record which can be accessed online if you know the design number.

NM can be used in through penetrations in 2 hour construction. I don't have a ceiling design number on hand at the moment but, here is one wall assembly.

Roger
 
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