Fiber Optic Cable in Classified area

[SJII]

I am new to desinging fiber optic infrastructure into classified & Hazardous areas. In the past I have suggested sealing fiber optic cables and their tubes via silicone foam when said cables are broken out (that is, outer jacket/sheath is stripped back) for splicing & routing.

In other words, as a cable enters a classified area and the cable enters an enclosure, the jacket is stripped back to access the individual fiber strands. In this scenario, the tubes (encasing the strands) are sealed to prevent gas from traversing one side of the cable to the next.

I am being told this is not in accordance with NEC, in particular Ch.5 - 501.15 (E) (3). That the individual tubes (or duct or innerduct) must be encased in a vaportight sheath or sealing and the process above is a violation of OSHA.

Can someone explain for me how to comply with this code?

Thanks,
SJ

 

[petersonra]

I don't recall that silicon is approved for sealing in such cases.

 

[rbalex]

Since your reference is to a Division 2 application, it is very likely the cable isn’t required to be sealed at all.

Cables Capable of Transmitting Gases or Vapors. Cables with a gas/vaportight continuous sheath capable of transmitting gases or vapors through the cable core shall not be required to be sealed except as required in 501.15(E)(1), unless the cable is attached to process equipment or devices that may cause a pressure in excess of 1500 pascals (6 in. of water) to be exerted at a cable end, in which case a seal, barrier, or other means shall be provided to prevent migration of flammables into an unclassified location.

rbalex - underline added