Understanding Fiber Optic Cable Jacket & Fire Rating


Fiber optic cable is constructed from the inside core, cladding, coating, strengthen member to the outside Cable Gland Manufacturer jacket. As the bare fiber is easily broken, fiber optic cable jacket is needed to provide protection for the shielding and conductors within the cable. The cable jacket is the first line of moisture, mechanical, flame and chemical defense for a fiber cable.Fiber cable jacket is made of various types of materials. It’s important to consider the jacket type when selecting the compatibility with the application’s connectors and environment. The table below contains some of the most common fiber cable jacket material types used both indoor and outdoor cables:According to EIA/TIA-598, the fiber optic cable color code defines the jacket color codes for different fiber types (SMF or MMF).


For single mode fiber, the jacket color is typically yellow. While for multimode cable, the jacket color can be orange (OM1 & OM2 cable), aqua (OM3 cable) and purple (OM4 cable). For outside plant cables, the standard jacket color is black. For more information about fiber optic cable color code, please refer to How to Identify the Fiber Optic Cable Color Code? Typically, there are eight levels of fire resistance for both non-conductive and conductive cables specified by NEC (National Electrical Code). All indoor fiber optic cables must be marked and installed properly for its intended use: plenums, risers and general purpose areas.


As mentioned above, OFNP and OFNR are two types of fiber optic cables that are used in buildings. OFNP cables have fire-resistance and low smoke production characteristics. This is the highest fire rating fiber cable and no other cable types can be used as substitutes. So these cables are mostly installed in plenum areas. Whereas, the fiber-resistance and low smoke of OFNR cables are not good as OFNP. OFNP plenum cables can be used as substitutes for OFNR cables. Through OFNR vs. OFNP, it is worth noticing that OFNR fiber optic cable cannot be used in plenum areas to replace OFNP cables, however, the latter can be used in the riser areas. Both OFNP and OFNR can be used in general purpose areas.