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	Subject - 300.22 Dave Nix Hi Guys, Picture a residential attached garage with living room and such next to it and bedrooms and bathrooms above. Often times the plumbing is enclosed by a soffit at the garage ceiling. To help prevent freezing a forced air duct is routed to this closed soffit area to "take the chill off" the plumbing. There is no return air to the furnace or anywhere else. The question is this; Does this soffit now qualify as an area in 300.22 which would restrict the type of wiring methods allowed? Thanks! Scott Vickrey After a reading of 300.22, I would have to say no because the prime purpose of this space is other than air handling. The first thing stated in 300.22 is "The provision of this section apply to the installation and uses of electric wiring and equipment in ducts, plenums and other air-handling spaces". This should be enough to rule out the entire section. We can go down the subsections and further rule out any doubt. (A)Ducts for Dust, Loose Stock or Vapor Removal. Not even close! (B)Ducts or Plenums Used for Environmental Air. This is not a duct nor a plenum, because it is not specifically designed to transport environmental air. (C)Other Space Used for Environmental Air. This is the only section where we come close to fitting into. And we fall off the hook at the statement. "it does not include habitable rooms or areas of the buildings, the prime purpose of which is not air handling". Could they have made that sentence harder to read? (D)Information Technology Equipment. Forget about it. Ryan_J I agree Scott. When you think about the intent of 300.22, it is so that if there were a fire there would not be noxious gases emitted from the non-metallic sheath of the cable. With that said, why worry about a piece of 14-2 if there is plastic plumbing pipe in the same location? Scott Vickrey Thanks for asking the question and forcing me to read this section of the code. I needed it. I have a question. What about the space above a suspended ceiling which is used to transport the return air? Is this included in subsection (C)? What about the tons of Cat 5 cabling in the suspended ceiling which is used to transport the return air. Where is the code governing that? That cable is almost all insulation. Dave Nix Hi Scott, Thanks for your response. I agree, this section would not apply. The area above a suspended ceiling as you describe would be (C). The cables there usually need to be rated with a "P" (for plenum)in their identification to be used in this location. These days, most data installers are aware of this and if there is a question about which cable to use, they usually just install the plenum type to avoid having to pull it all out and start over again. Dave Nix Hi Ryan, I agree. This was also my logic and understanding of the intent. Thanks!