Plenum or not

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rcddcabling

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I plan to run OFNR cabling from my data center to another technology space in my facility. In the data center, the cold air is supplied via perforated access floor tiles; my cabling will traverse the data center overhead (no underfloor cabling) in ladder type cable tray and transition out of the room to solid bottom cable tray with a solid cover. The run spans a common hallway, a battery room, back into a common hallway, and then into the other technology space where I again distribute overhead via ladder type cable tray. All of my through penetrations are properly firestopped, as well as are all of the gaps within the cable tray at each point of penetration. Can I run riser rated cabling or do I need to call-out for plenum? Please advise. Thanks.

[ March 07, 2005, 09:30 PM: Message edited by: rcddcabling ]
 
Re: Plenum or not

sounds like you are running cable in some portion of a return air plenum. go into your ahu room and you will see that the return air is pulled from the overhead area between the ceiling grid and the overhead slab? this is return air and is a plenum---you will need plenum rated cable....
 
Re: Plenum or not

and the battery room's enviromental air is common to the rest of the space??? if so, and the other spaces are supplied conditioned air only through the floor vents-- i would say you have no plenum other than the floor....
 
Re: Plenum or not

The battery room and the common hallway are supplied conditioned air via exposed supply ductwork. Can a common hallway be classified as a plenum?
 
Re: Plenum or not

No, you do not have a plenum.

The problem is you do have a plenum, depending on who is looking at it.

Plenum: A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system.

Therefore, if you get any pushback on the issue, just ask why your common or office spaces (or your house) for that matter aren't considered a plenum The wiring (attached computer cords, desk lights, CAT5 cabling) in those spaces are not plenum rated.
 
Re: Plenum or not

Based on that definition and my situation, is it accurate to say that riser rated cabling infrastructure complies with the NEC?
 
Re: Plenum or not

every battery room i have worked in is a separate system due to the production of hydrogen gas. the basic idea here is to protect normal enviromental air from being contaminated by cable jacketing that can produce toxic fumes. i saw an article that said a two foot piece of 2 inch pvc can produce enough toxic gas to kill every person on a typical high rise office floor!

we have had rulings in this area that contend that in a typical high rise apartment, that the area above ceilings and chases is now "plenum". there is no movement of air, but it is open to the enviroment of the apartment??? this was the local interpitation! i am curious, what is the actual difference in cable cost between riser cable and plenum cable?
 
Re: Plenum or not

Riser - $1.45 per foot
Plenum - $1.81 per foot

Total cost did not drive the solution; schedule and availability of material put me in a pinch.
 
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