Fiber Optics: Cable Jacket & Fire Rating

Fiber Optic Cables are incredible data transfer mediums with a very fragile core. The fiber cables are built inside out, with everything based around protecting and enhancing the core. The Outer Jacket is designed as a barrier for moisture, mechanical, fire, and chemical defense. In this article, we will review the different Jacket Materials, Color Codes, Fire Ratings, and Purpose Ratings.

Important Terms

Plenum - an Area in a building used for air flow/ distribution such as a drop ceiling or raised floors. This is most common in commercial settings.

Riser - an Area in a building such as a shaft, duct, etc. that runs vertically through the building and passes through one or more floors.

General Purpose- all other areas of the building that are not Plenum or Riser.

Fiber Optic Jacket Materials

There are many different options for fiber optic jacket types. The biggest consideration is the environment of use, as there are different codes pertaining to permitted uses for certain materials.

Jacket Color Code

All Fiber Optic Color codes are according to the EIA/TIA-598 and define the different fiber types. Single Mode Fiber is usually yellow, Multimode Fiber comes in Orange(OM1 and OM2), Aqua(OM3 and OM4) and Lime Green(OM5). Certain manufacturers have also defined MTP trunk cables by a magenta jacket. For outside, industrial plant locations, the standard jacket color is black.

Cable Fire Rating

Under the National Electrical Code, there are 8 levels of fire resistance for both non-conductive and conductive cables. Indoor cables must be marked visibly and installed per their listed use. An important thing to note is the substitutional hierarchy of the fire ratings. Plenum Rated cable can be used for Plenum, Riser, and general purpose. Riser Rated cables can be used in Riser and GP locations, and General Purpose can only be used for just that.