The Process of Pulling Fiber Optic Cable

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Installation methods for copper cables and optical fibre cables are almost similar, but have some additional precautions are needed. Since fibre optic cables are designed with additional strength members, they can be pulled with much greater force than copper wire if you pull it correctly. We need to remember a few rules when pulling fiber optic cables.

Do not pull on the fibres, pull on the strength members only! The cable manufacturer gives you the perfect solution to pulling the cables, they install special strength members, usually duPont Kevlar aramid yarn or a fiber glass rod to pull on. Use it! Any other method may put stress on the fibres and harm them. Most cables cannot be pulled by the jacket. Do not pull on the jacket unless it is specifically approved by the cable manufacturers and you use an approved cable grip.

Do not 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.

Do not 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 fibers, maybe immediately, maybe not for a few years, but you will harm them and the cable must be removed and thrown away.

pulling a fiber optic cable
Installation of fiber optic cables

Do not twist the cable. Putting a twist in the cable can stress the fibers too. 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! If you are laying cable out for a long pull, use a “figure 8” on the ground to prevent twisting (the figure 8 puts a half twist in on one side of the 8 and takes it out on the other, preventing twists.) And always use a swivel pulling eye because pulling tension will cause twisting forces on the cable.

Check the length. Make sure the cable is long enough for the run. It’s not easy or cheap to splice fibers and it needs special protection. Try to pull the cable longer. Light-weight cables are easy to pull up to about 2 kilometres, provided the cable weight is lower.

Conduit and Innerduct: Outside plant cables are either installed in conduit or innerduct or direct buried, depending on the cable type. Building cables can be installed directly, but you might consider putting them inside plenum-rated innerduct. This innerduct is colored and will provide a good way to identify fiber optic cable and protect it from damage, generally a result of someone cutting it by mistake. The innerduct can speed installation and maybe even cut costs. It can be installed quickly by unskilled labour, then the fiber optic cable can be pulled through in seconds. You can even get the innerduct with pulling tape already installed.

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