outside plant fiber optic cable

Merry Christmas
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New member
North Carolina

When an outside plant fiber optic cable is brought into a building and the route exceeds 50 feet, code says that this cable has to be place in emt or rigid pipe. Does this emt or rigid have to be "air tight"?

I have been asked to investigate the requriments as they apply to this application.

What does NEC write regarding this scenario?


Staff member
retired electrician
Re: outside plant fiber optic cable

Conduit is never air tight. There are no special rules for the conduit used for non-listed fiber optic cables. Just install the conduit per the Chapter 3 Article that applies. Note, that if your fiber has a conductive member, that the conduit msut be rigid or IMC and bonded to the buildings grounding system. See 770.50 and its exceptions.


Senior Member
Re: outside plant fiber optic cable

oh boy did we have fun with this one...

the problem here is that most outside plant cable with certain exceptions [like teck 90] is not rated for riser or plenum applications.

this means that you have only a short length of osp allowed indoors before you have to splice to a plenum or riser rated indoor cable. hence the requirement for emt or rigid conduit.

we have encountered similar problems with osp cat5 and cat3 cable, although the cost of splicing data cable is obviously lower than fiber terminations.
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