CommScope
makes a significant amount of optical fiber cable every year. Inevitably, every
year we also get a few calls from customers after the cable was installed asking,
“what happened to this cable?” The cable has a flat side, or the buffer tubes
are crushed, or worse yet, the fiber is broken.
Since every reel of fiber cable we produce has a Web Trak identification number, we
can run the fiber quality test report, or as some in the construction industry call it, the
birth certificate, and see that the cable tested well and all the fibers were
intact. The cable met all dimensional and mechanical specification tolerances
as it left our factory.
So how did the cable end up damaged?
CLICK TO TWEET: CommScope gets a lot of questions in the field about fiber cables. Here are some of the most common questions and answers.
Early in my career, I was in contract cable construction,
installing my first reel of fiber cable in 1988. While there was a lot of care
taken during the installation, no one had provided us with best practices. The
cable was installed without damage due to a great deal of luck. Realizing this,
I have since devoted a significant part of my career to defining and teaching
best practices for installing fiber optic cables.
In aerial applications, I have a “top 6” common failures and
the appropriate best practice to correct them:
- Reel placed too close to the set-up pole:
Ideally, the reel needs to be placed 1.5 – 2 times the height of set-up
attachment. For example, an 18-foot attachment would require the reel to be 27
to 36 feet away.
- Improper set-up block: Always use a 45-degree
roller block for this, not a single roller block or a set-up chute.
- Lack of appropriate break-away swivel: Always
use a break-away swivel on the lead end of the cable. Check to make sure it has
the correct shear pin rated for that cable’s maximum pulling tension.
- Use of single roller at tangential poles
(30-degree line change or greater): Always use a 45- or 90-degree roller block
based on the change of pole line angle.
- No one assisting the reel: The reel should
always be attended, and the rotation of it assisted to reduce back tension.
- Paying cable off from bottom of reel: The cable
should always be paid off from the top of the reel.
Here is my “top 8” for underground applications:
- Improper set-up block: Always use a minimum of
45-degree roller block for this. In most instances, a 90-degree block is needed
or even a series of angle blocks, not a single roller block or a set-up chute.
- Lack of appropriate break-away swivel: Always
use a break-away swivel on the lead end of the cable. Check to make sure it has
the correct shear pin rated for that cable’s maximum pulling tension.
- Incorrect application or no application of
lubricant: A qualified cable-pulling lubricant should always be used.
- As noted above, the reel should always be
attended, and the rotation of it assisted to reduce back tension.
- Paying cable off from bottom of reel: The cable
should always be paid off from the top of the reel.
- Reel not positioned to face the opposite
direction of the pull.
- Failure to proof the duct and clear it prior to
beginning pull: While it takes some extra time, it is an important step in a
successful installation.
- Exceeding fill ratio of a conduit: Always verify
the fill ratio of a conduit. CommScope offers a free calculator for pulling
cable into conduits called PullMaster.
At the end of the day, we’re always here to support you in
your deployments. We’d also love to hear your success stories. That reminds me
of a favorite saying: "Success is no accident. It is hard work,
perseverance, learning, studying, sacrifice and most of all, love of what you
are doing or learning to do.”