Rat Hole Fire Safety

[bobgaggle]

I recently did a load in at a new theater, they have rat holes through every wall to run cables, and a sign above each saying the plug is to always be in place for safety reasons. As I've learned it, these things exist to avoid people from propping open fire doors to run cables through and to eliminate trip hazards. I get their usefulness for those purposes, but since you can't put the plug back in once you've got a cable in there, doesn't the fire safety aspect sort of disappear? Or is it just less of a risk because you've got a 8" opening in the wall rather than a 3'x7' hole where the fire door should be shut?

 

[derekleffew]

Portable cables can penetrate walls, floors, or ceilings through approved "pass-through" chases. (a mouse hole that was not fire-stopped would no doubt be a stretch). That's not the same as installing portable cables permanently inside a wall. ...

http://www.stifirestop.com/products/product-selector/fp-intumescent-firestop-plugs/ or similar/equivalent should be applied around the cable(s) any time the cover/plug is not in place. I suspect the duration of the installation and the attentiveness of the AHJ are factors.

 

[Chris15]

I've always seen fire pillows used to fill the remaining gaps in this situation. In some cases, they are permanently "chained" close to the opening in question...

 

[BillConnerFASTC]

I think of these: http://www.firestop.com/productssheets/pdspillow.pdf

 

[Chris15]

This would be typical of what I'm used to: http://www.wormald.com.au/__data/assets/pdf_file/0006/287349/Wormald_AUS_FirePillow_Sept11_email.pdf

Looks fairly similar to Bill's linked product, though not sure about the intumescent properties...

 

[JohnD]

Intumescent-that is a new word to me, here is what wikipedia has to say:
http://en.wikipedia.org/wiki/Intumescent

 

[derekleffew]

Look up related tumescent. Sort of like/but different http://chemistry.about.com/od/firec...ference-Between-Flammable-And-Inflammable.htm .

 

[StradivariusBone]

Look up related tumescent. Sort of like/but different http://chemistry.about.com/od/firec...ference-Between-Flammable-And-Inflammable.htm .

 

[BillConnerFASTC]

So does tumescence mean in-tumescent, or is in-tumescent what comes before tumescence?

 

[Dan0010]

i was thinking instead of having a plug they should have used this. i had an engineer who only wanted to use this since it easy to just run cables and just pull them out whenever you wanted. forget plugs and pillows. http://www.stifirestop.com/ez-path/

 

[Dionysus]

When I saw this thread I had "nightmares" of fire-caulking, speaking of Intumescents. Yes it is important that these holes are "filled", you must have an intact fire-barrier with the necessary rating (depending on the building, wall in question, local rules, etc). The idea is to prevent smoke and vapours (fire) from spreading unchecked through the building and giving people the chance to escape (not to mention firefighters a chance to save something).

And yes plugs and pillows typically in your instance. For cables or conduit passed directly through the wall (permanent install) fire-caulking is required to seal any crack or seam. The product seals the hole, and when exposed to heat will expand to ensure that the hole remains sealed for as long as possible.

 

[BillConnerFASTC]

I have a hard time getting too excited about the actual safety these afford in many cases, where the hole is low and to the stage. In any stage fire, below the neutral pressure plane, which will most likely be in the middle third of the stage height, the pressure is negative so no smoke is going to be leaving the stage. In most of rhe buildings i work on these are close to the floor and usually the only rated walls are the stage walls. However the holes up high in a corridor, like linking overhead cable trays, is a problem. It just points out the uniqueness of the stage and auditorium and why things like!e this have to be considered in a big picture. Sprinklers is another one, since fires on stages generally start around the lighting and its what above that is burning at first. Using distance above the floor, since in most other occupancies the combustibles start at the floor, need better evaluation when applying to stages.

Just trying to point out that its easy to loom at an isolated close up view and not see the big picture, and a classic error in planning for safety. The Beverly Hills Supper Club fire is one where this cost a lot of lives, addressing additions but not the whole.

 

[StradivariusBone]

What sort of protocol does one have to go through to install conduit through a proscenium wall? Not to hijack (I think I'm ok since the OP's question was answered), but we currently annoy our AHJ because we run a few cables through a propped door from the catwalks to the pin rail gallery and down to the SM podium. I'd love to put in a 3" piece of EMT through the wall near the door. I'm also not sure of the best way to bore through 1' of poured concrete...

 

[BillConnerFASTC]

Core a hole that is oversized - probably hire a concrete coring company - put in canduit, and seal annular space with fire caulk - usually red or reddish. Best answer - hire a contractor to do it all.

 

[AlexDonkle]

What sort of protocol does one have to go through to install conduit through a proscenium wall? Not to hijack (I think I'm ok since the OP's question was answered), but we currently annoy our AHJ because we run a few cables through a propped door from the catwalks to the pin rail gallery and down to the SM podium. I'd love to put in a 3" piece of EMT through the wall near the door. I'm also not sure of the best way to bore through 1' of poured concrete...

What Bill said, hire a contractor. One addition though, have straight cut threads on both sides of the conduit, and a conduit cap on both sides connected with ~24" stainless steel swivel chain. This lets you seal up the hole when not in use, and use 4" conduit for this type of install, not 3".

Keep in mind that if the hole is cut too large, it must be sealed differently to meet fire code. (may or may not require mineral wool to be packed into the annular space, before sealing with Hilti 601 or similar sealant)

Another interesting company to look at for sealing temp cables through walls is Roxtec. http://www.roxtec.com/us/

 

[Dover]

The ez-path is another good option. I don't know how it would stand up to dally pulling of feeders. But for moderate term temporary and semi-permanent installations they are great.

http://www.stifirestop.com/products/ez-path/

 

[StradivariusBone]

Core a hole that is oversized - probably hire a concrete coring company - put in canduit, and seal annular space with fire caulk - usually red or reddish. Best answer - hire a contractor to do it all.

We're a public school PAC so I put in the query to see if any of our county maintenance teams has the proper equipment. I did once have the pleasure of coring through a pored concrete floor from a IDF closet down to the MDF. I worked as a cable ape for a business telco/data installer in my salad days and we were working at an older building in Orlando adding a fiber backbone, but all the conduit was stuffed and fiber doesn't like to be greased and shoved into pipe so much so the plan was to use a Ryobi drill and a 2" bit to "core" the floor.

After about 90 minutes, almost starting a fire, destroying the drill, and cleaning the melted plastic off my gloves we were almost halfway done.

I figured this is not the correct methodology.

 

[de27192]

The ones I put on an install last year had socks inside which you pushed the cable through. In the event of temperature exceeding a set amount, the sock melts expands and fills the gap providing a seal. Seems sensible. Obviously you can say goodbye to the cable as you will have a sticky socky mess in the middle of it but it should help save the building.

http://www.jcjoel.com/wp-content/uploads/2013/07/Cable-Pass-Datasheet.pdf

 

[venuetech]

as i understand fire prevention theory much of is to prevent oxygen from feeding the flame. so it is important that whatever device is used it must restrict the air flow both ways hot or cold. So depending on heat to activate the device does not stop the flow of oxygen

 

[de27192]

It comes down to your risk assessment and what you see the risk that you are trying to mitigate as being.

Fire doors are not intended to be (and very seldom are) complete air locks. Fire doors are intended to prevent the spread of a fire through the door. So ultimately where you use cable passes to prevent people running cables through doors, your cable pass also only really needs to prevent fire spreading, and not necessarily protect oxygen from being fed to the fire which is already burning.

Bear in mind that the sock will often melt before the fire physically reaches it - owing to (a) how hot the air gets in a building fire, and (b) how hot the cable will be if it is running to a place where the fire is happening.