How Do You Write Material Specification for Optical Fiber Cables?

Writing specifications and stressing on the properties of the material that shall be used in the construction of fiber optic cables need a lot of technical knowledge about materials, cable and their test methods. For most of the staffs working with cable buyers, this task is troublesome and usually, they look for similar specifications. Here is a help for you. This is a standard format for the majority of the fiber optic cables used in the underground installation. You can modify as per your requirement.

1 Fiber Optic Cable: Provide all-dielectric, gel-filled, loose-tube, low water peak single-mode fiber (SMF), suitable for underground (i.e., in conduit) and lashed aerial outside plant installation. Ensure that all components that comprise a single length of cable are continuous and of the same material. Manufacturers shall furnish only commercial off-the-shelf materials, equipment, and components.

1.1 Optical Fiber: Ensure, the optical fibers used in the cable meet or exceed the requirements in ITU-T G.652D recommendations. Ensure that optical fibers meeting the additional requirements as follows are used in the cables:

(MFD) Mode field Diameter @1310 nm9.2±0.4µm
Cladding Diameter125.0±0.7µm
Coating Diameter (uncolored)245±10µm
Core concentricity error≤ 0.8 µm
Cladding no-circularity≤1.0%
Cladding/coating concentricity error≤ 12 µm
Attenuation Coefficient (At 1310 nm)≤ 0.34 dB/km
Attenuation Coefficient (At 1550 nm)≤ 0.21 dB/km
Attenuation Coefficient (At 1383 nm)≤ 0.30 dB/km
Cable cut-off wavelength≤ 1260 nm
Chromatic Dispersion Coefficient (At 1285 – 1330 nm)≤ 3.5 ps/(nm·km)
Chromatic Dispersion Coefficient (At 1270 – 1340 nm)≤ 5.3 ps/(nm·km)
Chromatic Dispersion Coefficient (At 1550nm)≤ 17.5 ps/(nm·km)
Zero-dispersion wavelength1302 – 1322 nm
Zero-dispersion slope≤ 0.090 ps/(nm2·km)
PMD link design value≤ 0.06 ps/√ km
Proof Test100 kpsi
Coating Strippability1.3 – 8.9 N
Fiber Curl Radius≥ 4.0 m
Permissible Bending Radius≥ 30 mm

Ensure that each optical fiber is glass and consists of a Germanium-doped silica core surrounded by concentric silica cladding. Ensure that all fiber in the buffer tube is usable fiber that complies with attenuation requirements. Ensure that fibers do not adhere to each other. Ensure that the fiber is free of surface imperfections and inclusions. Ensure that all fiber optic core glass is from the same manufacturer.

1.2 Buffer Tubes: Ensure that the fiber optic cable includes loose buffer tubes that isolate internal optical fibers from outside forces and provide protection from physical damage as well as water ingress and migration. Ensure that buffer tubes provide freedom of movement for internal optical fibers. Ensure buffer tubes allow for expansion and contraction of the cable without damage to internal optical fiber. Ensure that fiber does not adhere to the inside of the tube. Ensure that buffer tubes permit intentional scoring and breakout without damage to the fiber. Ensure that each fiber optic cable buffer tube contains 12 fibers per tube unless otherwise noted in the plans. Buffer tubes shall be made of polybutylene terephthalate (PBT) or polycarbonates (PC).

1.3 Color Code: Ensure that the marking and color-coding of the fibers and buffer tubes conforms to telecommunication industry requirements as detailed in the TIA/EIA-598-C or IEC 60304 standards. Ensure that colors are permanent and stable during temperature cycling, and not subject to fading or smearing onto each other or into the water-blocking material. Ensure that fibers are colored with UV curable inks that remain clearly distinguishable as the intended color.

1.4 Strength Member: Ensure that the fiber optic cable contains a dielectric central strength member and dielectric outside strength member to prevent buckling of the cable and provide tensile strength. Ensure that the fiber optic cable can withstand a pulling tension of 2700 Newtons during installation without increasing the fiber strain of 0.6%, without changing other optical fiber characteristics after the tensile load is removed, and without damage to any components of the fiber optic cable.

1.5 Water Blocking Compound: Ensure that the fiber optic cable stranded core is wrapped with a water-blocking tape and included with a water swellabe yarns to prevent the ingress of water within the cable. Ensure that the water-blocking tapes and yarns are non-nutritive, dielectric, and homogeneous, and free from dirt and foreign matter. Use dry water-blocking material for fiber optic cables used for either aerial or underground installations. Apply dry water-blocking compound longitudinally around the outside of the central buffer tubes. Helical wrapping is not preferable. Construct all cables with water-blocking tape that complies with the requirements of the EIA/TIA-455-81B standard and is subjected to water penetration tests as defined in the IEC 60794-1-2 method E5 or EIA/TIA-455-82B.

1.6 Ripcord: Ensure that the cable contains at least one ripcord under the sheath. Ensure that the ripcord permits the removal of the sheath by hand or with pliers.

1.7 Filler/dummy: Filler/dummy rods may be incorporated in the cable stranded core to lend symmetry to the cable cross section if required. Fillers shall be made of suitable materials such as polyethylene.

1.8 Outer Jacket: Ensure that the fiber optic cable is jacketed with Polyethylene such as LLDPE, MDPE and HDPE that is free of blisters, cracks, holes, and other deformities. Ensure that the nominal jacket thickness is a minimum of 1.5 mm. Apply the jacketing material directly over the peripheral tensile strength members (if used) and water-blocking material. Ensure that the polyethylene contains carbon black to provide ultraviolet (UV) protection and does not promote the growth of fungus. The carbon black used in the polyethylene shall be dispersed uniformly and shall comply with ASTM standards.

The outer surface of the cable jacket/sheath shall be marked with the cable manufacturer’s name, fiber type, fiber count, and Year of manufacture, the words “FIBER OPTIC CABLE,” and the sequential cable lengths marked in meters. Ensure that the actual length of the cable is +/- 1% of the length indicated by the marking. Provide legible marking with a contrasting color to that of the cable jacket. White color printing is preferred on a black color jacket. If re-reprinting is unavoidable due to printing errors, Yellow color printing shall be used for re-printing.


Author: Praveen Gupta

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