Need opinion- whole house fans- attic becomes a plenum?

[macmikeman]

If I wire in a whole house fan for a customer , does all the romex wiring in the attic suddenly become a code violation due to the use of nm in air handling space? Thinking ahead so I can write a proposal that covers this .

 

[GoldDigger]

I am not sure that a stage along a purely exhaust air stream counts as an environmental air space since none of that air will ever return to an occupied space.
The motivation for special treatment of wiring in air handling spaces is to prevent recirculation of flame, smoke and combustion products into occupied spaces.
Not sure whether all of the wording supports that distinction though. Have to look harder at it.

 

[Dennis Alwon]

I hope not as millions of homes are done this way. The air is exhausted out not into the house so there is no issue with toxin from the nm. I also would not call the attic space a plenum. If you did then the entire interior of your home would be a plenum.

 

[GoldDigger]

It is not being called a plenum, since it was not constructed for that purpose.
It is close to the definition of other environmental air space, except for the "environmental" part.

 

[mwm1752]

Attic with an attic fan exhaust does not fit the definition of plenum.


Plenum. A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system.
(C) Other Spaces Used for Environmental Air (Plenums).
This section shall apply to spaces not specifically fabricated for environmental air-handling purposes but used for air-handling purposes as a plenum. This section shall not apply to habitable rooms or areas of buildings, the prime purpose of which is not air handling.

 

[GoldDigger]

And an air exhaust space does not form part of an air distribution system....

 

[Sierrasparky]

I would agree.