Any Exception in a Plenum ?

[mstrong1]

I have a situation where I want to run a truly insignificant length of non-plenum cable in a plenum and am wondering if there is any exception for this sort of thing.

I have a low voltage sensor installed in a ceiling tile, I need to run it to an interface box on the plenum side of the tile via a shielded 30ga wire jacketed in PVC. The total run is about 1 foot and the cable is less than 1/10th of an inch OD.

I can find plenty of 24ga wire that is rated plenum and am using that for the interface box to the destination, however anything over 30ga is too big to safely solder to the delicate sensor.

Any exception for a tiny bit of non-plenum cable ?

 

[hbiss]

In a situation like that, the box would be located directly above the item being mounted and integral to mounting and supporting the device.

-Hal

 

[JFletcher]

Welcome to The Forum

You do not have a plenum, you have a "other space used for environmental air", which is covered by 300.22 (C). Look under 300.22(C)2 for the answer. I would say your one foot of wire, if it is part of the equipment, or looks like it is a factory part of the equipment, is okay. PVC is not an approved raceway for plenum or air handling spaces, nor is any plastic, see 300.22(C)1.

 

[hbiss]

From your profile I see that you are designing this? I would not want to see a device poked through the ceiling tile with a "tail" coming out of it into a splice box that is laying on the tile above the ceiling.

If you take care of that issue you automatically take care of your original question.

-Hal