Guidelines for Fibre Optic Cable Installation

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Guidelines for Fibre Optic Cable

  1. Never directly pull on the fibre itself. Fibre optic cables have Kevlar aramid yarn or a
      fibreglass rod as their strength member. You should pull on the fibre cable strength
      members only!

  2. Never exceed the maximum pulling load rating. On long runs, use proper lubricants
      and make sure they are compatible with the cable jacket. On really long runs, pull
      from the middle out to both ends. If possible, use an automated puller with tension
      control or at least a breakaway pulling eye. Know and observe the maximum
      recommended load rating of the cable.

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3. Never exceed the cable bend radius. Fibre is stronger than steel when you pull it
    straight, but it breaks easily when bent too tightly. These will harm the fibres, maybe
    immediately, maybe not for a few years, but you will harm them and the cable must
    be removed and thrown away!

4. Always roll the cable off the spool instead of spinning it off the spool end. This will
    put a twist in the cable for every turn on the spool! Never twist the fibre cable.
    Putting a twist in the cable can stress the fibres too.

5. Make sure your fibre cable is long enough for the run. Fibre splicing make things
    complicated and expensive. And it needs special protection. Try to make it in one
6. Indoor cables can be installed directly, but you might consider putting them inside
    inner duct. Inner duct provides a good way to identify fibre optic cable and protect it
    from damage, generally a result of someone cutting it by mistake! You can get the
    inner duct with pulling tape already installed.

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7. Plan the Installation. Create a detailed, written plan of installation. You can eliminate
    95% of the problems installers can encounter by simply creating this plan. The plan
    should include equipment and supplies, fibre cable specification, location of
    equipment, testing requirements, data forms for testing, personnel experience level
    and assignment, installation methods, identification of potential problem areas,
    safety issues, etc.

8. Pull, do not push cables. Pushing can result in violation of the bend radius.
9. Monitor the supply reel. Monitoring the supply reel during installation is necessary to
    prevent violation of minimum bend radius.

10. Communicate along the path of installation. When installing long runs, communicate
    and monitor along the path of the installation. Fibre cables can and do jump from
    unmonitored pulleys. The minimum crew should have one person monitoring the
    pulling equipment, one monitoring the supply reel, and one coordinating all involved
    in the installation.

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11. Use proper tools and techniques. A vehicle for pulling the cable is not a proper tool,
    unless a breakaway swivel is also used. Proper techniques depend on the cable
    design and the location of the installation. For example, proper technique is pulling a
    cable into a conduit. Proper technique is placing or laying a cable in a cable tray or

12. Use fibre optic cable lubricant. Lubricate the cable when installing in conduits.
    Lubrication reduces the pulling load and the chance of breakage. The lubricant has to
    be compatible with the cable jacket material.

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13. Train installation personnel. Properly train and instruct the people who will do the
    installation. Proper training reduces expense through reduction of breakage and
    excess attenuation.

14. Use the figure 8 technique. Divide long pulls into several shorter pulls, using the
    figure 8 technique for storing cable at the intermediate locations. The cable is placed
    on the ground in a figure 8 pattern. This pattern is large, at least 10-20 feet from top
    to bottom of the pattern. When all the cable is placed in this pattern, the pattern is
    lifted and flipped over, so that the loose end is on top. This loose end is pulling into
    the next section of conduit or duct. This technique prevents twisting in the cable.

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15. Comply with vertical rise limits. Know and observe the maximum vertical rise
    distance limit. Exceeding this limit can result in fibre breakage, excess attenuation,
    and, in loose tube cables, fibres sliding from cables. Cables in vertical installations
    that are longer than the vertical rise limit must be tied off at distances less than this
    limit. Loose tube cables must be looped.
16. Allow for thermal expansion and contraction. In outdoor installations, a common
    practice of 2.5 foot sag for 150 foot span is good for thermal expansion and
    contraction. Failure to allow for thermal expansion can result in increased
    attenuation and breakage of fibres.
17. For tough installations, use loose buffer tube fibre cables. Loose tube cables can be
    more forgiving of abuse than tight buffer cables. The reason is that the excess length
    of fibre in the buffer tube and the ability of fibre to move from low stress region to
    higher stress region.
18. Observe the temperature operating range. Install a cable in locations in which the
    temperature range imposed is within the temperature operating range. Violation of
    the temperature operating range can result in excessively high attenuation.
19. Cap or seal water blocked cables. Cap off or seal the ends of cables with water
    blocking gel or grease. These materials can flow out of the cable, causing
    maintenance problems in cable end boxes.
20. Protect fibres and buffer tubes. Confine fibres and buffer tubes in protective
    structures, such as splice trays and cable end boxes. Fibres and buffer tubes do not
    have sufficient strength to resist breakage due to normal handling of copper cables.
21. Loop vertically installed loose tube cables. Install vertical, unfilled, loose tube cables
    with loops to prevent the fibre from slipping to the bottom of a vertical run. If this
    happens, attenuation can increase and fibres eventually break.
22. Check continuity and attenuation. Check the continuity and attenuation of the cable
    before each operation. These checks should be performed as-received/before
    installation, after installation, after splicing, and after connector installation.
23. Mark cable as “Fibre Optic Cable”. Mark cable as “fibre optic cable” in all locations
    in which it can be easily reached. Such marking will alert electricians to the nature of
    the cable.
24. Make As-Built Data logs. Make as-built data logs on all cables. Keep these data
    available to those who will perform maintenance and troubleshooting. These data
    logs should include both insertion loss measurement and OTDR measurements.
25. Safety precaution – no food, drink or smoke. Do not eat, drink, or smoke in any area
    in which bare glass fibre is created. Bare glass fibres can cause splinters which are
    very difficult to find and remove.
26. Safety precaution – do not look into fibre without checking status. Never look into a
    fibre, cable, or connector unless you know for sure that there is no laser light in the
    fibre. For extensive work with fibre optics, safety glasses with IR filter is
27. Leave service loops. Leave cable and fibre service loops everywhere. You will regret
    not doing so. Service loops allow you to pull excess cable or fibre into a location
    where you have experienced a problem. It is much cheaper to pull in a service loop
    than to replace an entire run of fibre cable.
28. Segregate or isolate the work area. Rope off or otherwise isolate the area of cable
    installation to prevent access to unauthorized or untrained personnel. This will avoid
    safety problems such as fibre splinters and unintentional abuse.

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29. For direct burial installations, the cable should lie flat in a trench, free of any large
    stones or boulders that may deform the cable.
30. Do not allow vehicles to drive over a cable.
31. Ensure that the proper cable length has been installed before cutting off excess cable.
32. Avoid placing cable reels on their sides or subjecting them to shock from dropping.
33. Fibre optic cables should be placed in their own dedicated ducts or trays. Do not mix
    copper cable and fibre cable in the same ducts or trays.
34. After the fibre optic cable is installed into a duct or inner duct, end plugs should be
    installed to provide an effective water seal. The ducts and inner ducts should be kept
    free of debris and maintained watertight at all times.
35. Ducts and inner ducts should be sized to meet present and future cable installation
    requirements. A maximum 40% fill ratio is a good rule of thumb to follow for duct
36. The fibre pulling rope or tape should be sequentially marked (foot or metre) for easy
    identification of distance.
37. The pulling tape should have a rating for greater than maximum anticipated pulling
38. Before the start of any cable pull, all ducts and cable vaults should be carefully
    inspected for damage or deterioration, and to address any safety concerns.
39. The electric spark generated by a fusion splicer can cause an explosion when
    flammable gases are present. Fusion splices should therefore not be used in vaults.
40. To minimize cable tensions, reel vault locations should be set near the sharpest bend
    locations. Pulling and reel locations should also be set at corner vaults where
41. Identify light wave equipment that will be used and ensure that the equipment will
    function properly with the fibre cable being installed.
42. When an outdoor rated fibre cable enters a building, it should be spliced to an
    indoor-type fibre cable within 50 feet from the cable entrance to meet NEC code.
43. All vertical cable must be secured at the top of the run. A split mesh grip is
    recommended to secure the cable.
44. The vertical attachment point should be carefully chosen to comply with the cable’s
    minimum bend radius while holding the cable securely.
45. If future cable pulls in the same duct or conduit are a possibility, the use of inner
    duct to sectionalize the available duct space is recommended. Without this
    sectionalization, additional cable pulls can entangle an operating cable and could
    cause an interruption in service.
46. A small amount of slack cable (20-30 feet) can be useful in the event that cable
    repair or relocation is needed.
47. Cables should be tested after shipping. Damage to cabling can occur during shipping
    or installation. Failing to test fibre cabling after it is delivered is a common mistake
    made by installers.
48. If insertion loss suddenly increases with an adapter or connector, the cause may be
    dirt. You should always clean the connector and adapter before plugging them in.
49. Properly attach the pulling eye and swivel to the cable. Ensure that the pulling eye
    and swivel assembly have no sharp edges and can easily fit through all conduits, pull
    boxes, and cable trays.

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50. When pulling the fibre out of a section, coil the cable on the floor in a figure 8
    pattern to avoid twisting. Continue the cable pull until all the cable has been pulled
51. Identify the exact fibre optic cable route and ensure that it meets all installation
    specifications. Obtain all required fibre cable installation authorizations and permits
    along the route.
52. Record all required fibre optic facility details, including proper route drawings, fibre
    assignments, loss readings, OTDR traces, etc.
53. Prepare emergency repair plans.
54. Only remove connector and adapter duct caps prior to making the connection. Do not
    let the connector tough any surface once the duct cap has been removed.
55. When making a connection, the connector should attach to the adapter smoothly. Do
    not rotate the connector when making the connection.
56. For screw-in connectors such as FC connector, tighten them only “finger tight”.
    Never force a connector onto an adapter.
57. A fibre optic cable should be tested three separate times during an installation: on the
    reel, the splicing test, and the final acceptance test.
58. Extreme caution should be observed when performing an aerial installation. The
    proper personnel should be contacted so that they are on the site when work is
    performed near high-voltage lines.
59. Cables that are installed in the vicinity of high-voltage power lines should be
    grounded, including all-dielectric cables.
60. Maintain proper clearance between the fibre optic cable and power cable at all times.
    Always make allowances for power cable sag due to weather and current conditions.
    Cable sag increases in warm weather or when power cable is passing heavy current.
61. When a steel messenger wire is used for aerial installation, avoid zigzagging the
    messenger wire from one pole side to the other. Instead, make sure it is kept on one
    side as much as possible.
62. Follow Building Codes: Always obey all local, and national, fire and building codes.
    Be sure to "firestop" all cables that penetrate a firewall. Use plenum rated cable
    where it is mandated, etc., etc.
63. Do make every effort to pull cables from a conduit in as straight an angle as
    possible. Pulling on an angle can cause damage to the cable.

64. Use a generous amount of cable pulling lubricant on the entire run, especially on the
    leader (pulling eye & mesh). The person may stop the cable pull from time to time to
    prepare and apply more lubricant. Use only lubricant that is expressly designed for
    cable pulling. When working in freezing temperatures, use a lubricant that is
    designed not to freeze.

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65. It is important to use a rope size that give minimal stretching during the pull.
    Stretching of the rope is undesirable for several reasons including that it makes for a
    very unstable pull, and takes away control from those doing the pulling.
66. Use extreme caution when removing the pull eye. Do not use a blade to slit the mesh.
    Instead, use a pair of electrician’s scissors or diagonal cutters. Work your way from
    the back of the cable toward the pull eye, while lifting the mesh upward, away from
    the cable.
67. It is extremely important to take an accurate measurement when planning an order
    for a custom pre-terminated fibre optic cable assembly. These custom assemblies
    cannot be returned unless out of box defective.
68. Optional pulling eyes are highly recommended. The pulling eye (and associated
    cable netting) will protect the pre-terminated ends during the pull.
69. Underground conduits, if newly installed, should be a minimum size of between 1.5"
    to 2". If the run is long, or if you anticipate the possibility of additional future pulls;
    Then you may want to install a conduit of up to 4" (or greater).
70. Try to design the conduit run with a few bends as possible. If there are too many
    bends in the run then you may consider installing junction boxes in lieu of bends.
71. Cable may be placed in a Figure 8 pattern if it needs to be removed from the reel.
    This pattern minimizes the accumulation of cable twist. Care should be taken to
    prevent cable damage while the cable is in this configuration.

72. The cable should not be installed in environments exceeding its specified maximum
    and minimum installation temperature. For loose tube and ribbon cable this is
    typically specified for an installation temperature of -30C to +75C.
73. Riser cables are generally required for vertical applications and plenum cables are
    required where there is a positive air pressure space.
74. The cable weight in an unsupported vertical rise shall be less than the specified long
    term operating load. Your manufacturer’s specification sheet should be consulted for
    specifics. Intermediate cable attachment points however are recommended for
    optimum performance.
75. Bonding and Grounding: Follow your company and local/national bonding and
    ground procedures when using fibre cable with metallic components.
76. When pulling the cable off the reel onto messenger mounted cable blocks, special
    care should be given to size and location of the 1st and last pulley. The reel should
    be placed as far as practical from the 1st pulley to minimize the angle of the 1st
    bend. A cable shoot/pulley larger than the specified bend radius is recommended to
    minimize the cable bend at the first and last pulley locations or at any location with a
    change in direction.

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77. On runs from 40m to 100m, use proper lubricants and make sure they are compatible
    with the cable jacket.
78. On runs over 100m, use proper lubricants and pull from the middle out to both ends.
79. If possible, use an automated puller with tension control or at least a breakaway-
    pulling eye.
80. Avoid placing fibre optic cables in raceways and conduits with copper cables to

    avoid excessive loading or twisting.
81. Attach cables with plastic clamps having large surface areas. Avoid pinching or
    squeezing cable. Cable clamps should be installed manually with gentle pressure.

82. Use a wet wipe to loosen particles on the end of the cable connector using a circular
    or straight wiping motion while using care to avoid wiping over area of pad that has
    already been used. Do not use a back and forth scrubbing action.

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83. Cleaning fibre optic transceivers. Choose an optical grade lint free swab that fits
    easily into the transceiver barrel. The swab should be gently placed into the barrel of
    the connector and rotate no more than one turn. DO NOT rotate back-and-forth or
    round-and-round because this could grind debris into the transceiver. The swabs
    should only be used ONCE.

84. Cable Blowing or Jetting in Duct Applications. A crash test should be performed to
    determine the maximum push force. Excessive pushing will cause the cable to cork
    screw in the duct or fold over which will damage the fibre.
85. Cable blowing. Consider the route to determine the maximum blowing distance.
    Follow the blowing equipment suppliers blowing distance recommendations; 3000 to
    6000 feet is a typical blowing length. A set up with multiple blowing machines may
    be required.
86. Cable blowing. Maintain proper air flow to “blow” the cable verses “pushing” the
    cable. Use an air compressor with a minimum of 375 cfm. The minimum air pressure
    in the duct should be 100 psi with 125 psi recommended.
87. Cable blowing air cooler. Air compressor cooler should be used as recommended by
    the blower equipment manufacturer. Typically this is when the ambient air
    temperature exceeds 80˚F.
88. Cable blowing. Use only cable/duct lubricants recommended by its blowing
    equipment manufacturer for optical fibre cable.
89. Do not store cable within the closure or pedestal unless there is enough room to
    accommodate the minimum specified cable bend radius.

90. Grounding: Cable with metallic components shall follow the bonding and grounding
    requirements of the customer and local or national codes.

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91. Midspan access of fibres in buffer tubes: To minimize fibre damage, use a Midspan
    Access Tool to open the buffer tube such as a Corning OFT-000. Care should be
    taken to use the correct insert size.

92. Conduit Installations General Information: Try to design the conduit run with a few
    bends as possible. If there are too many bends in the run then you may consider
    installing junction boxes in lieu of bends.
93. Use plastic bushings on conduit ends to avoid damage to the cable during the pull.

94. For cables using aramid yarn alone as the strength member, the jacket can be
    removed to expose the yarn. The yarn should be tied in a knot with the pull rope, so
    that the jacket will not be inadvertently used for strength. Optionally, the jacket can
    be tied into a tight knot before pulling. After pulling, the knot should be cut off.

95. For cables using aramid yarn and a fibreglass central member, a pulling grip should
    be used. The strength member should be attached independently. This can be
    accomplished by weaving the strength member into the fingers of the grip, and then
    taping it together. All strength members should be gripped equally to ensure proper
    distribution of tension.

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96. Buried cable installations. Identify cable locations with surface markers. Anticipate

97. Test jumpers must be of the same fibre core size, performance and connector type as
    the cable system and should be around one to five metres long.

98. Number of 90 degree turns. The number of 90 degree turns on a pull shall not exceed
    6 for aerial cables and 4 for underground cable-in-conduit.
99. Pulling underground fibre optic cable. Special fibre optic blocks should be used on
    all turns or angles.

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100.      And always use a swivel pulling eye because pulling tension will cause
   twisting forces on the cable.

101.      If cables are present in ducts through which the fibre cable is to be pulled, the
   existing cable types should be identified and the owner of the cable called to inform
   him of the action, and to identify any safety concerns.