Fire rated boxes

[Sierrasparky]

Hi
I've come across a lot of TV outlet installs lately where folks are using cut in boxes like this Arlington LVDR2

These have the UL mark for fire rating stamped in the back of the box.
How can these be rated for a 1 hour wall supported by drywall and a open ring?
I have also seen Carlon blue cut in boxes with a 1 hour stamp in the box too.

 

[jumper]

Isn't the open ring part for LV only?

As far as cut in boxes, I think the regular cut ins are 1 hour rated also. Why, IDK, I can only guess that it was UL flame tested and given that listing. Aren't regular fire rated assemblies/walls 2 hour rated and the 2 hour boxes must be secured to framing?

 

[JFletcher]

Isn't the open ring part for LV only?

As far as cut in boxes, I think the regular cut ins are 1 hour rated also. Why, IDK, I can only guess that it was UL flame tested and given that listing. Aren't regular fire rated assemblies/walls 2 hour rated and the 2 hour boxes must be secured to framing?

afaik, yes, yes and yes.

Arlington's spec sheet

http://www.aifittings.com/catalog/s...w-voltage-box-for-existing-construction/LVDR2

says that box is 2hr rated. :huh:

I dont know how the open backed part gets a 2 hr rating on a cut in. It's not the LV that's the problem, it's the hole in the wall.

afaik, exceeding 100sqin of opening per 10' of wall requires extra measures, like putty pads. Extremely common in hotels to blow that 100sqin.

 

[Sierrasparky]

afaik, yes, yes and yes.

Arlington's spec sheet

http://www.aifittings.com/catalog/s...w-voltage-box-for-existing-construction/LVDR2

says that box is 2hr rated. :huh:

I dont know how the open backed part gets a 2 hr rating on a cut in. It's not the LV that's the problem, it's the hole in the wall.

afaik, exceeding 100sqin of opening per 10' of wall requires extra measures, like putty pads. Extremely common in hotels to blow that 100sqin.

We'll maybe this old fart was taught wrong. I was always under the impression that in a rated wall you just cannot cut a hole and put a plate. There needs to be a box. Also the box must be supported by a framing member not the drywall.

If you look at the UL book Metal boxes are rated for fire walls , however they need to be supported by the framing. UL also states that for Non metallic you go by the manufactures listing

 

[JFletcher]

We'll maybe this old fart was taught wrong. I was always under the impression that in a rated wall you just cannot cut a hole and put a plate. There needs to be a box. Also the box must be supported by a framing member not the drywall.

If you look at the UL book Metal boxes are rated for fire walls , however they need to be supported by the framing. UL also states that for Non metallic you go by the manufactures listing

I think we are right, because not once in the 20 or so hotels where I wired the v/d/v did we use open backed boxes anywhere, especially the walls between guest rooms, which, in addition to a fire rating, must also have a sound rating.

 

[north star]

~ @ ~

" How can these be rated for a 1 hour wall supported by drywall
and a open ring? "

The box with a 1 hr. fire rating may not have been intended to be applied
in a true fire rated wall application, but rather, the installer just grabbed
the first elec. box he came to.......Installing in just the sheetrock with no
attachment to a stud, and no ring are, IMO, ...two more strikes against
the application being a fire rated wall application.......Even with putty
pads, the installed box would not be considered a true "tested & approved",
fire rated assembly.

Was the box in the OP installed a true fire rated wall application, or an
interior wall in that room, or something else ?


~ @ ~

 

[Sierrasparky]

~ @ ~


The box with a 1 hr. fire rating may not have been intended to be applied
in a true fire rated wall application, but rather, the installer just grabbed
the first elec. box he came to.......Installing in just the sheetrock with no
attachment to a stud, and no ring are, IMO, ...two more strikes against
the application being a fire rated wall application.......Even with putty
pads, the installed box would not be considered a true "tested & approved",
fire rated assembly.

Was the box in the OP installed a true fire rated wall application, or an
interior wall in that room, or something else ?


~ @ ~

Yes true fire wall separating units in condos. I see this all the time.