PVC in Plenum

[JJWalecka]

I over heard a discussion regarding the use of PVC above a Plenum ceiling. It was basically stated that because the suspended ceiling was used as a “return” the PVC would not be Code compliant.
I am looking in article 352 but can not find the discrepancy. Perhaps it is in the building Code?
Any comments would be appreciated.

Justin J. Walecka

[RUWired]

Justin, Article 300.22(B) explains the wiring methods allowed, and pvc is not listed

(B) Ducts or Plenums Used for Environmental Air Only wiring methods consisting of Type MI cable, Type MC cable employing a smooth or corrugated impervious metal sheath without an overall nonmetallic covering, electrical metallic tubing, flexible metallic tubing, intermediate metal conduit, or rigid metal conduit without an overall nonmetallic covering shall be installed in ducts or plenums specifically fabricated to transport environmental air. Flexible metal conduit shall be permitted, in lengths not to exceed 1.2 m (4 ft), to connect physically adjustable equipment and devices permitted to be in these ducts and plenum chambers. The connectors used with flexible metal conduit shall effectively close any openings in the connection. Equipment and devices shall be permitted within such ducts or plenum chambers only if necessary for their direct action upon, or sensing of, the contained air. Where equipment or devices are installed and illumination is necessary to facilitate maintenance and repair, enclosed gasketed-type luminaires (fixtures) shall be permitted.
Rick

[RUWired]

300.22(C) also covers plenums above suspended ceilings

FPN: The space over a hung ceiling used for environmental air-handling purposes is an example of the type of other space to which this section applies.
Rick

[cpal]

Justin

300.22 (C) is titled as "Other Space Used for Environmental Air."

I would explain this as a suspended ceiling where enviormental air is generally returned through a egg crate type tile(s) to the mechanical unit. This type of installation is not a plenumn.

ref to the definition in art 100.

That being said it appears that the general rule would not permit a PVC jacket in such locations this section is stricter for sections 300.22(A) and (B)

Charlie

[marcb]

No shirt, no shoes, pvc located in a plenum....no dice

[iwire]

It's not a plenum to the NEC.

[JJWalecka]

Rick, Charlie, Marcb and Iwire thank you for your time and effort.

I should have done more research before asking the question.


Justin J. Walecka

[ryan_618]

Originally Posted by JJWalecka

Perhaps it is in the building Code?

Actually, it would be in the mechanical code, such as the IMC. Anything in an air handling space must have a certain flame spread and smoke developed index.

[JJWalecka]

Ryan,

Thank you!


Justin J. Walecka