The current state of FTTX installations
With FTTX networks reaching increasingly higher numbers of users, their architectures require a lot of planning and forward-thinking. With more extensive and dense fiber distribution, high-count backbone fiber optic cables need to be dropped into lower-count cables that reach end users directly on more installation points.
What is mid-span access in Fiber Optic Cables?
Mid-span access is the process of opening an entry point in the middle of a laid cable to access its fibers. This is necessary for drop, fiber optic cable repair, and signal distribution to end users. It involves the physical manipulation of cables, removing their jackets, metallic or dielectric armors (when dealing with Armored Cables), and all the internal components that help protect the optical fibers.
Mid-span access can be vital to splice, connect, and repair optical fibers. It is also an efficient way of dropping only the necessary fibers without interrupting the flow of others. A basic example for this would be a backbone Loose Tube Armored Cable with 72 fibers, that we need to drop into a 4 fiber drop cable, considering that a Waveoptics® Armored Cable with this configuration has 12 loose tubes rolled around a central strength member with 12 fibers each, we can prepare the cable mid-span to access and splice the 4 fibers we need to drop, leaving the other fibers intact, ensuring a continuous run.
Initial considerations when handling cables
Optical fibers are delicate by themselves, and cables need to provide protection to transmit data and information over long distances, this is why armored cables are one of the most durable and resistant choices for backbone fiber optic cables: designed to protect loose tubes and fibers, they have rugged constructions and integrated metal or glass armors. But this also means that their preparation requires more technical savvy, involving specialized tools.
With this in mind, we have prepared an essential guide to armored fiber optic cables and their preparation for mid-span access.
Preparation of an armored fiber optic cable for mid-span access
The tools we recommend for the process contemplate the unsheathing of the cable’s jacket and armor, the removal of internal aramid yarns and water-blocking tape, and the unsheathing of loose tubes to access optical fibers.
We will need:
- A Miller® armored cable slitting tool
- A flathead screwdriver
- A marker and flexometer
- One loose tube unsheathing tool
- A pair of pliers
- Isopropyl alcohol and wipes*
- A seam ripper to help remove yarn and protective tape
- ANSI Z87-certified protective goggles, and level 5-certified gloves for safety
*Note: this is necessary if you’re planning to access a gel-filled cable.
First, use the flexometer to measure the total length of the entrance point as necessary. The total cable slack varies depending on the type of cable, fibers, and splice closure used when splicing fibers and accessing the loose tubes. Although, it is recommended to make a cut of around 120 inches for cables up to 288 fibers.
Mark the middle point of the total length with the marker, and then divide it by 2 to reach both sides to mark them as well, these will be used later.
Set the Miller® Armored Cable Slitting Toll in the option for round cuts, then, on the first marked point, measure the blade to penetrate the jacket and armor of the cable.
We have a video showing how to set the Miller® ACS tool correctly to unsheath armored cables, that you can watch HERE.
Once penetrated the jacket and armor, set the lever to the straight cut position and make a straight cut along the cable until reaching the other side.
Now, set the tool 180° degrees to make a second straight cut on the other side of the cable, this will help open an access point on the cable. To access them, make a third and final round cut on the cable, about 2 inches from the first round cut.
Use the pliers to take that section of the jacket and armor out of the cable and use the seam ripper to expose the ripcords on both sides of the cable.
Now use the pliers to roll the ripcord around for leverage on one side. Pull along the cable to remove the jacket and armor. Use the straight cuts on the cable as a guide. Repeat this process on the other side with the other ripcord.
Once you’ve reached the other side, just separate the jacket and armor and you will successfully unsheath the cable to access its internal components.
Use the seam ripper to carefully pull the yarn and water-blocking tape off the loose tubes, and cut them with the scissors.
Now proceed to cut the central strength member by carefully unrolling the stranded loose tubes and separating them. Leave a tolerance of around 4 inches on both ends to use the strength member as a force reliever when using a splice closure.
Feel free to check the next video that explains in detail how to prepare your armored cable for mid-span access:
Who are we?
FONCS is a distributor of fiber optic solutions for telecommunications companies.
Do you have a question? Contact our experts HERE.
WAVEOPTICS® designs and manufactures outdoor and indoor/outdoor fiber optic cables for various applications.
With over 10 years of experience and over 18 production lines in its ISO-9001 certified plant, it provides high-quality products through talented personnel and specialized technology, complying with IEC, Telcordia, and ICEA fiber optic cable standards.
FONCS. Your network, our goal.
- Hayes, J. H. (2021b, April 29). The ins and outs of midspan access. Electrical Contractor Magazine. Retrieved August 19, 2022, from: https://www.ecmag.com/section/integrated-systems/ins-and-outs-midspan-access
- Hayes, J. H. (2021, April 15). A comprehensive scope of work: Fiber optic cable plant design questions. Electrical Contractor Magazine. Retrieved August 12, 2022, from: https://www.ecmag.com/section/integrated-systems/comprehensive-scope-work-fiber-optic-cable-plant-design-questions
- The Fiber Optic Association [thefoainc]. (2020, November 23). Lecture 59 Fiber Optic Cable Midspan Access [Video]. YouTube. https://youtu.be/2P8m1IKZjn4