300.22 exceptions

[Kimura]

Exception: This section shall not apply to the joist or stud spaces of dwelling units where the wiring passes through such spaces perpendicular to the long dimension of such spaces.

Does this mean nm can be run across (perpendicular) through the plenum and NOT be in violation ? The nm I need to run across is for lights in the above room. This nm is not affiliated with HVAC in any way.

The "plenum" in this case is your typical joist cavity, encased with sheet metal

thank you

 

[augie47]

The exception does cover the situation you describe.

 

[infinity]

The "plenum" in this case is your typical joist cavity, encased with sheet metal

How is it encased in sheet metal? That sound like it's a piece of metal duct not a plenum constructed from the stud space created by the drywall and wood studs.

 

[Kimura]

It's sheet metal attached to the bottom of the floor joists. Please see pic. The yellow arrow would be the direction of the nm, but would be behind the metal. The joists run left to right in the pic

I was wondering if I could (temporarily) pull back the sheet metal, run the romex through (perpendicularly) and reattach the metal

 

[infinity]

It's sheet metal attached to the bottom of the floor joists.

I was wondering if I could (temporarily) pull back the sheet metal, run the romex through (perpendicularly) and reattach the metal

Yes you can do that. I was thrown off by the word encased.

 

[Kimura]

Thank you!

 

[Dennis Alwon]

The old way was to pan the joist for cold air returns. You should fire caulk the holes after you put your wires thru

 

[Kimura]

Thank you. Yes plan on using 3m's product for that

Just want to make sure everyone saw that this nm is for lights in the above room and is in no way affiliated with the HVAC system