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It has been a while since I worked installing low voltage cabling. When I did, I seem to remember my employer always using / pulling plenum cable anytime we worked above a drop ceiling in a commercial building even if the space was not true plenum space because of the potential for the space to become plenum space in the future or a duct disconnecting, etc.

I recently have rented an office in the lower level of an apartment building that is around 15 stories tall and there is a drop ceiling in the office. I was looking to add a few CAT6 pulls and I have riser cable sitting around. I have observed that the existing cable runs above the drop ceiling all use are using riser cable. There is even a riser PVC tubing type of conduit that is specifically labeled "riser". That tube is a 200 ft run from the telco closet on the other end of the building that Verizon used when they installed the FiOS internet.

I understand this to be all code compliant because the space isn't actually plenum space, but am curious if my former employer was overly cautious or what best practice does.

I googled a little and I also came across an article saying plenum cable was only needed in plenum space if the run in the plenum space was 50ft or more, but do not recall, nor can I find any code reference that allows this. 300.22 says plenum space needs plenum cable or metallic conduit from what I read. Is there an exception in the code anywhere that backs up what I read?
 

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Usually plenum cable has a rating that makes it acceptable to use in most locations, so it was probably easier to stock/order one type of cable than multiples of the same types.

And that's not to say I havent seen non-plenum rated cable in an actual air space, either.
 

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Tables in the NEC allows substitution of Plenum cable for Riser, but does not allow substitution of Riser for Plenum.
 

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Commerical in the bottom of 15 story residential. Just guessing it is all fire rated above your ceiling. Call your local code enforcement folks. FR cable is not that expensive compaired to the libiality of something goes wrong in your unit.
 
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