Nec code clarification

[RBM]

I'd like a clarification of 300.22C (exception).

Can a NM cable pass through a residential heating system return plenum which was created by closing the bottom of the ceiling joists with sheet metal. The cable passes through the plenum perpendicular to the joists

Thanks, rbm

[John Grabowski]

*I picked up my 2011 book today Roy. The exception is still there. I interpret it as such that it is permissible for the NM cable to pass through the created plenum.

[RBM]

Thanks John, that's how I'm reading it as well.

>

[Steve Barker]

My HVAC man says no, unless it's plenum rated cable. but i did it anyway.