# Cat 5e above drop ceiling commercial



## drspec (Sep 29, 2012)

Is the ceiling a plenum space?


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## Bbsound (Dec 16, 2011)

drspec said:


> Is the ceiling a plenum space?


If it is, don't forget to use plenum ty-wraps.


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## mikeh32 (Feb 16, 2009)

Bbsound said:


> If it is, don't forget to use plenum ty-wraps.


not a requirement till 2013 i thought?


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## Bbsound (Dec 16, 2011)

mikeh32 said:


> not a requirement till 2013 i thought?


Not a requirement where? NEC
We still have all those other pesky building codes, mechanical codes, specs, etc.


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## FlyingSparks (Dec 10, 2012)

Bbsound said:


> Not a requirement where? NEC
> We still have all those other pesky building codes, mechanical codes, specs, etc.


Don't forget those local ordinances too!


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## newspark80 (Feb 20, 2011)

Found this very helpful site
http://www.telcodepot.com/information/3/24/when-plenum-rated-cable-is-needed.html


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## don_resqcapt19 (Jul 18, 2010)

Some IT specs require the use of plenum rated wire above all drop ceilings. Something about slight performance loss with non-plenum rated cable in a high heat/humidity area. (at least that is what they told me when I asked why we had to use plenum rated cable in a ceiling that was not used for return air)


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## FlyingSparks (Dec 10, 2012)

don_resqcapt19 said:


> Some IT specs require the use of plenum rated wire above all drop ceilings. Something about slight performance loss with non-plenum rated cable in a high heat/humidity area. (at least that is what they told me when I asked why we had to use plenum rated cable in a ceiling that was not used for return air)


I call bs on that. It its all about distance, proper termination, no insulation damage, and xtalk. Plenum rated cable resists a fire longer, preventing a release of toxic plastic chemicals during an fire evacuation. You can read about the mgm casino fire.


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## halfamp (Jul 16, 2012)




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## don_resqcapt19 (Jul 18, 2010)

FlyingSparks said:


> I call bs on that. It its all about distance, proper termination, no insulation damage, and xtalk. Plenum rated cable resists a fire longer, preventing a release of toxic plastic chemicals during an fire evacuation. You can read about the mgm casino fire.


I know what the plenum rating is for and I have a copy of the fire investigation report for the MGM fire.

I was told that the plenum jacket keeps the humidity out better that the standard jacket, and higher moisture in the cable increases cross talk, but as you say, probably BS.


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## don_resqcapt19 (Jul 18, 2010)

Carol cable says that the "velocity of propagation" changes between their CMR and CMP Cat5e cables. 70% for the CMR and 72% for the CMP.


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## TLinSTL (Nov 28, 2011)

I've never understood, and maybe this is how it is everywhere, but here they don't consider open ceilings to be plenum. So if the return air is being sucked from a room that's only ceiling is the metal or concrete above it, and cat5e is run through rings or J-hooks, you don't have to use plenum rated cable, but if a drop ceiling is added and everything else remains the same, plenum cable is now required.

To me, that doesn't make any sense because the toxins are still being sucked into the air return either way.

What I also don't understand about it is the HVAC system is shut down when there is a fire so it really is irrelevant.

I will admit that burning, non-plenum cat5e sucks though and basically takes your breath away.


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## mikeh32 (Feb 16, 2009)

the thing about plenum cable ties, and velcro is going to be in the new code


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## Ty Wrapp (Aug 24, 2011)

TLinSTL;1040006
I will admit that burning said:


> I once asked an inspector why plenum cable was required. He said that in a fire plain pvc cable gives off toxic fumes, whereas plenum does not. I asked who is going to stick around in the burning building, breathing the fumes.


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## FlyingSparks (Dec 10, 2012)

That's silly. In the MGM fire, people were unaware of the fire in the restaurant in the first place. So toxic fumes made their way up the building creating disoriented individuals and killing some.


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## chewy (May 9, 2010)

The guy at the Belden seminar said he cannot stress enough the use of plenum cable and if he had his way it would be mandatory. He was from Australia and said a friend of his was a firefighter in Brisbane and was clearing a building without scba on and noted a mist on the floor into his comms then walked back outside and dropped dead in the stairwell.


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## FlyingSparks (Dec 10, 2012)

chewy said:


> The guy at the Belden seminar said he cannot stress enough the use of plenum cable and if he had his way it would be mandatory. He was from Australia and said a friend of his was a firefighter in Brisbane and was clearing a building without scba on and noted a mist on the floor into his comms then walked back outside and dropped dead in the stairwell.


My facility uses plenum for everything, even patch cords. But I have a huge problem believing it helps transmission reliability/performance.


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## chewy (May 9, 2010)

FlyingSparks said:


> My facility uses plenum for everything, even patch cords. But I have a huge problem believing it helps transmission reliability/performance.


I dont believe/care if it does or not, CAT6a will transmit at CAT6a performance or we find another supplier plenum or non plenum. From a safety standpoint it seems sensible though.


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## don_resqcapt19 (Jul 18, 2010)

FlyingSparks said:


> That's silly. In the MGM fire, people were unaware of the fire in the restaurant in the first place. So toxic fumes made their way up the building creating disoriented individuals and killing some.


Yes, but a very very small percentage of those fumes came from the wiring or other building systems. The vast majority came from the building finishes and furnishings. The volume of toxic smoke produced by the finishes and furnishings is orders of magnitude greater than that produced by building wiring and piping systems.


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