plenum wiring required, as per NEC code?

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techtalk

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Hello everyone, this is a great site/forum!

I am having a debate (read: delay) with a GC on a project regarding whether plenum communications cabling is required or not. Client's site is a commercial suite space in a single-floor building. As the client's IT Consultant, I created the layout for data and phone wiring, including notes to require plenum-rated cabling. The GC does not think that the cabling will be in a 'plenum' area.

The front-half of the client's suite is typical office space with a drop ceiling. The back-half of the suite is wide open, like a warehouse space, with no dropceiling. The separation between the two areas does not contain a wall that goes up to the building's roof. This means that from the "warehouse" area, you can look back and see the area above the office space. (they use part of it for storage (above drop ceiling above offices).

There are air returns in the drop ceiling in the offices, which leads me to believe that the space above is a plenum area and therefore requires plenum-rated cabling. Is there something that I am missing, or is it that straight-forward?

P.S. The reason why this is important is that I will be completing the terminations. Given that I designed the project's data and phone requirements and will be completing the terminations, I am concerned about the liability factor, should a fire occur in the future.

P.P.S. I work directly for the client, not for the GC.
 
Unless the return air flows directly through the space over the drop ceiling, I wouldn't call it an air plenum. If the returns are ducts from a register/vent in the ceiling grid to the air handler, then the space above isn't be a plenum. (And likewise, AFAIK unfinished space, such as the "warehouse" area, never counts as plenum. OTOH, local codes probably vary on this.)

I'd go with the GC on this, in that it's not required. However, if you want to pay for plenum cable, it's your nickel.
 
The general rule is, if the open space is used as the return for the air handler, then it is a plenum space. If the the returns are ducted back,then not a plenum.

But if you specified plenum cable in the bid,and multiple contractors bid it that way,it should be required.
Rick
 
Note "The general rule is, if the open space is used as the return for the air handler, then it is a plenum space. If the the returns are ducted back,then not a plenum."
This is an Air Handling space, not a plenum. In general no wiring is allowed in a plenum, unless needed to act on the air inside.
 
plenum cable

plenum cable

the state building inspector required me to use plenum cable in the air handling space over a drop in ceiling.....when all the supply and return lines were in duct. i didn't argue..i just priced the job for plenum cable.
 
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