non-plenum building w/ a few plenum spaces

[malachi constant]

I am the engineer on a three story office building. Mix of open offices and private offices. About a quarter of the private offices have plenum rated ceilings above them. I have designed the low voltage infrastructure to provide conduit for all wiring as it passes through the plenum space. A building inspector is stating that once you need to use rated cable (or protection i.e. conduit) you need to use it throughout the entire building. This is not my experience, though my experience in plenum areas is limited.

So anyone know that code? If you have to use rated cable or protective conduit once in a building, you have to use it everywhere?

 

[ron]

Different low voltage circuits are handled by different code sections. Overall, I don't see a problem with your design.
For example 725.3(C) directs you to 300.22(C) which indicates that you can put the cable in certain raceway. IT doesn't indicate that the entire circuit must be in raceway, just the area pertaining to 300.22(C) (air handling ceiling).

 

[malachi constant]

That's corresponds with my knowledge and experience. I'm going to say as much to the inspector, see if he knows something I don't. I'll check back in if he does. Thanks!

 

[don_resqcapt19]

Note that if you are using "plenum signaling raceway" you still have to use plenum rated cable within that type of raceway. 725.61(A).