Fire Rated wall

[1793]

I have been asked to estimate installing a recess luminaire in a "High Rise" Condo. The wall I need to pull the power form and install the switch is a wall that backs up to another Condo. As I understand this is a Fire Rated wall.

I will be cutting in the switch and fishing the wire, MC, up and over to the luminaire, Walls are constructed using metal studs and I think there is insulation as well.

I am in need of some input on what is required and or how to install the box(s) for this job.

Thanks in advance.

 

[mcclary's electrical]

I have been asked to estimate installing a recess luminaire in a "High Rise" Condo. The wall I need to pull the power form and install the switch is a wall that backs up to another Condo. As I understand this is a Fire Rated wall.

I will be cutting in the switch and fishing the wire, MC, up and over to the luminaire, Walls are constructed using metal studs and I think there is insulation as well.

I am in need of some input on what is required and or how to install the box(s) for this job.

Thanks in advance.

You have a much bigger concern.
That is you are putting a recessed fixture in a fire rated ceiling. You have to box around the fixture with two layers of 5/8" sheetrock. Or they do make a fire rated cap that I've used before. But they're about $200 bucks per fixture. The switch in the fire rated wall cannot be within two feet of an outlet on the other side of the wall. If you use a meatal box you have to put putty on it. Be careful.

 

[infinity]

The switch box will need to be connected to a structural member like a stud. You cannot install a style of box that is only supported by the sheetrock.

 

[ivsenroute]

You need to find out exactly what the rating of the assembly is and install equipment that will maintain that rating. You will have to take into consideration what is on the other side of that wall and where boxes are located on both your and the other side.

This does not sound like a true "Fire Wall", this sounds like a fire rated partition or assembly. You will be penetrating one side only which means you will only be penetrating the "memberane" of the assembly, not through the entire assembly itself. There is a difference with how they are handled.

 

[JFletcher]

Where the MC comes out of the wall needs the correct firestop as well. Hilti FS-One is what I use.

300.21 puts penetrations of fire rated walls on building codes and product specifications, so you will have to check those to be sure. I believe most metal boxes have a two-hour rating if properly installed (source). Putty puds, like the Hilti CP617L, allow closer than 24" between devices, but not back-to-back. I'd use one anyway, because in addition to the fire rating the wall is probably sound rated as well.

 

[ivsenroute]

3M has a lot of products available

Here are a lot of choices: http://solutions.3m.com/wps/portal/3M/en_US/fire/stop/resources/one/firestop-systems/?PC_7_RJH9U5230OLLB0I4HB8HRT3GS0_nid=8T0J7HRDNNge

 

[infinity]

Where the MC comes out of the wall needs the correct firestop as well. Hilti FS-One is what I use.

300.21 puts penetrations of fire rated walls on building codes and product specifications, so you will have to check those to be sure. I believe most metal boxes have a two-hour rating if properly installed (source). Putty puds, like the Hilti CP617L, allow closer than 24" between devices, but not back-to-back. I'd use one anyway, because in addition to the fire rating the wall is probably sound rated as well.

Is the 24" dimension dependent on there being no stud between the boxes on opposite walls?

 

[ivsenroute]

Even with 24" oc framing you cannot get two boxes 24" apart between a stud bay. We rarely see 24" oc framing anyway.

 

[JFletcher]

Is the 24" dimension dependent on there being no stud between the boxes on opposite walls?

Studs have no bearing on the 24" rule. Even if separated by one or two studs, boxes that are <24" apart horizontally in fire rated walls will need some sort of added fire protection, whether it be mineral wool batting, sheetrock partitions around the boxes, or putty pads.

Here's a link from 3M that is very informative.

 

[infinity]

Studs have no bearing on the 24" rule. Even if separated by one or two studs, boxes that are <24" apart horizontally in fire rated walls will need some sort of added fire protection, whether it be mineral wool batting, sheetrock partitions around the boxes, or putty pads.

Here's a link from 3M that is very informative.

Nice link. I wonder why they use the size of the box and not the size of opening cut into the wall? A 2 gang cover on a 4" box would have a much larger hole cut in the wall then say a 4 11/16" box with a single gang cover.

 

[zappy]

Nice link. I wonder why they use the size of the box and not the size of opening cut into the wall? A 2 gang cover on a 4" box would have a much larger hole cut in the wall then say a 4 11/16" box with a single gang cover.

Ive never seen a 4-11 single gang mud ring? I guess there out there somewhere.

 

[e57]

The switch box will need to be connected to a structural member like a stud. You cannot install a style of box that is only supported by the sheetrock.

Really - a code ref????

Ive never seen a 4-11 single gang mud ring? I guess there out there somewhere.

Really - got several dozen downstairs - common item for me...

 

[iwire]

Really - a code ref????

UL orange book.

 

[e57]

Anyway most of the high rises around here - at least the newer ones have PT slabs that act as the deck above - poured in pendant boxes - and intumesant paint... The rooms and halls often have a soffeted area for HVAC - sometimes as parts rocked off as plenum - and you can add any cans you want - no additional measures... (Except in the plenum...) And always rocked off from common areas and other units...

Some of the older high-rise have exposed steel - and so long as you don't disturb any - you can add any openings you want - if rocked off from common areas and other units... (Not always so.)

The walls however are a different story. Usually inner tenant walls can be treated as normal. But any partitions between units, or common areas are 1-2 hour rated.

Anyway - the building managment IMO is usually pretty intimate with the fire protection measures and wall/cieling ratings of their building - I ask 'em. Sometimes a good way to start a relationship for more work...

 

[e57]

UL orange book.

Don't have it - so whats it say?

 

[iwire]

Don't have it - so whats it say?

I don't have it either but from what I recall it essentially requires the electrical boxes to secured to a structural member in order to maintain the rating of a rated wall assembly.

 

[roger]

Don't have it - so whats it say?

From the UL Fire Resistance Directory (The Orange Books)

WALL AND PARTITION ASSEMBLIES

Metallic Eletrical Outlet Boxes

Listed single and double gang metallic outlet and switch boxes with metallic or nonmetalliccover plates may be used in bearing and nonbearing wood stud and steel stud walls with ratings not exceeding 2h. These walls shall have gypsum wallboard facings similar to those shown in Design Nos. U301,U411, and U425. The metallic outlet or switch boxes shall be securely fastened to the studs and the opening in the wallboard facing shall be cut so that the clearance between the box and the wallboard does not exceed 1/8 in. The surface area of individual metallic outlet or switch boxes shall not exceed 16 sq in. The aggregate surface area of the boxes shall not exceed 100 sq in per 100 sq ft of wall surface.

Roger

 

[cowboyjwc]

The boxes no longer need to have the 24" seperation, as long as you fire pad both boxes. Also don't forget that since it's unit to unit, the fire pads will be required to have a sound rating also. Not that easy to find.

 

[JFletcher]

The boxes no longer need to have the 24" seperation, as long as you fire pad both boxes. Also don't forget that since it's unit to unit, the fire pads will be required to have a sound rating also. Not that easy to find.

Wasn't easy to find, but I found it. Google led me to this thread:

http://forums.mikeholt.com/showthread.php?t=93201

and post #8 - yours! Pretty cool I think. I didn't know the rating had to be 50 or higher, but once I did it was just a matter of looking at putty pad specs to find ones rated >50. The part # I mentioned before has a rating of 55.

Nice link. I wonder why they use the size of the box and not the size of opening cut into the wall? A 2 gang cover on a 4" box would have a much larger hole cut in the wall then say a 4 11/16" box with a single gang cover.

I don't know, but I thought it was opening size, not box size. I agree with you - there must be some reason why box size is chosen over opening size for the 100in2/100ft2 rule.

 

[cowboyjwc]

Wasn't easy to find, but I found it. Google led me to this thread:

http://forums.mikeholt.com/showthread.php?t=93201

and post #8 - yours! Pretty cool I think. I didn't know the rating had to be 50 or higher, but once I did it was just a matter of looking at putty pad specs to find ones rated >50. The part # I mentioned before has a rating of 55.

Man, I getting up there with Pierre and Bob. It used to be harder to find fire pads with a high enough sound rating. Good job.