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Wednesday, February 8, 2017
Question:
Fiber Optic cable routed in a Class 2 Division 1 location. OSP fiber optic cable typically doesn’t have a metallic component to it, so does it require to be installed in rigid conduit and NEMA 9 enclosures when routed through Class 2 Division 1 Location? I believe that it does per Article 502.10(A) (1) (4).
Confusion is added in Article 500.8(F) it states “Optical fiber cable contains conductors that are capable of carrying current (composite optical fiber cable), the optical fiber cable shall be installed in accordance with the requirements of Article 500, 501, 502, and 503 as applicable.” It doesn’t mention nonconductive fiber optic cable.
Please confirm that non-conductive fiber optic cable routed in a Class 2 Div 1 rated area is required installed in rigid conduit and the boxes and fittings shall be threaded bosses connections and the conduits are sealed with electrical sealing putty per 502.15.
Additionally non-conductive fiber routed in a Class 2 Division 2 requires only be routed in rigid, intermediate, emt, dust tight wireways, dust tight fittings and enclosures and sealed with electrical sealing putty per 502.15
Thanks, Jim Gavin
A
Answer:
Hey Jim thanks for your question. Some of the confusion has been addressed because the words "with or without current carrying conductors" have been added to 500.8(F) in the2017 NEC. So yes optical fiber cable in a Class II Division 1 location must be installed in threaded right metal conduit or threaded steel intermediate conduit as stated in 502.10(A)(1)(4). The boxes and fittings in Class II Division 1 locations must have threaded bosses and be dusttight as stated in 502.10(A)(3).
In Class II Division 2 locations electrical metallic tubing, dustight wireways, and cable trays are also allowed to be used as stated in 502.10(B)(1)(8). The boxes and fittings in Class II Division 2 locations must be dusttight but do not need threaded bosses as stated in 502.10(B)(4)
If a raceway is connected to an enclosure that is required to be dust ignitionproof and one that is not, a means of keeping the dust out is required as stated in 502.15. Electrical sealing putty is allowed as explained in the Informational Note.