I recently saw my co-worker disassemble a computer using a single tool. Was it the right tool for the job? Yes and no. It was the tool I had … it worked, however, there is definitely more than one tool that would have made the task easier! Definitely, many fiber optic installers know this situation very well. As a reminder, how many of you have used your splicer tool kit (cable knife / scissors) to remove the sheathing or even cut a protection tube and then use the scissors to cut the Kevlar? Did you touch the glass? Accidentally cut the glass and had to start over?

Properly splicing and terminating fiber optic cable requires special tools and techniques. Training is important and there are many excellent sources of training available. Don’t mix your power tools with your fiber tools. Use the right tool for the job! Being proficient in fiber work will become increasingly necessary as the importance of data rates, fiber to the home, and fiber to facilities continue to increase.

Many factors distinguish fiber installations from traditional electrical projects. Fiber optic glass is very brittle; Its nominal outside diameter is 125um. The slightest scratch, mark or even speck of dirt will affect the transmission of the light, degrading the signal. Safety is important because you are working with glass that can dig into your skin without being seen by the human eye. Transmission grade lasers are very dangerous and require protective goggles to be a must. This industry has been primarily concerned with voice and data grade circuitry that could tolerate some signal disruption or slowdown. The person speaking was repeated, or the data was relayed. Today we are dealing with IPTV signals and clients that will not tolerate pixelization or momentary image blocking. All the mentioned situations are reason for the client to look for another carrier. Every situation could have been avoided if due attention had been paid to the techniques used in preparing, installing and maintaining fiber optic cables.

With that said, why don’t we review the basic fiber preparation? Wire strippers are used to remove the 1.6 – 3.0mm PVC outer jacket on single and duplex fiber cables. The serrated kevlar cutters will cut and trim the kevlar resistance member directly under the cover and the tampon spacers will remove the acrylate (buffer) layer from the bare glass. A protective plastic layer is applied to the bare fiber after the drawing process, but before it is wound. The most common coating is a UV-cured acrylate, which is applied in two coats, resulting in a nominal outside diameter of 250um for the coated fiber. The coating is highly engineered, provides protection against physical damage caused by environmental elements, such as extreme temperatures and humidity, exposure to chemicals, stress points … etc. while minimizing optical loss. Without it, the manufacturer could not wind the fiber without breaking it. 250um coated fiber is the basic component of many common fiber optic cable constructions. It is often used as is, especially when no additional mechanical or environmental protection is required, such as inside optical devices or splice closures. For added physical protection and ease of handling, a secondary layer of polyvinyl chloride (PVC) or Hytrel (a thermoplastic elastomer that has desirable characteristics for use as a secondary shock absorber) is extruded over the 250um coated fiber, increasing the outside diameter up to 900um. This type of construction is known as “tight damping fiber.” Tight Buffered can be single fiber or multi fiber and are seen in local networks and indoor applications. Tight-damped multi-fiber cables are often used for applications within buildings, elevators, general buildings, and plenums.

‘Loose tube fiber’ generally consists of a bundle of fibers encased in a thermoplastic tube known as a buffer tube, which has an inside diameter that is slightly larger than the diameter of the fiber. Loose tube fiber has a space for the fibers to expand. Under certain weather conditions, a fiber can expand and then shrink over and over again or it can be exposed to water. Fiber cables sometimes have ‘gel’ in this cavity (or gap) and others that are labeled ‘dry block’. You will find many loose tube fibers in outdoor plant settings. The modular design of loose tube cables typically supports up to 12 fibers per shield tube with a maximum number of fibers per cable of more than 200 fibers. Loose tube cables can be fully dielectric or optionally shielded. Shielding is used to protect the cable from rodents such as squirrels or beavers, or from protruding rocks in a buried environment. The modular design of the buffer tube also allows for easy drop of fiber bundles at intermediate points, without interfering with other protected buffer tubes heading to other locations. The loose tube design also aids in the identification and management of fibers in the system. When there is protective gel, you will need a cleansing gel such as D-Gel. Each fiber will be cleaned with the 99% alcohol and gel cleaner. Cleanroom wipers (Kim Wipes) are a good choice to use with the cleaning agent. The fibers within a loose tube gel filled cable generally have a 250 um coating, so they are more brittle than a tight damping fiber. Industry standard color coding is also used to identify the buffers, as well as the fibers in the buffers.

A ‘rotary tool’ or ‘cable cutter’ can be used to cut a ring around and through the outer sheath of ‘loose tube fiber’. Once you expose the durable inner buffer tube, you can use a ‘Universal Fiber Access Tool’ which is made for a single central buffer tube inlet. Used on the same principle as the mid-span access tool (which allows access to the tight, multi-colored buffer coated damping fibers), the double blades cut the tube lengthwise, exposing the buffer coated fibers. Fiber manipulation tools such as a putty knife or pick will help the installer access the fiber that needs to be tested or repaired. Once the damaged fiber is exposed, a hand tool will be used to remove the 250um coating to work with the bare fiber. The next step will be to clean the end of the fiber and prepare it for cutting. A good cut is one of the most important factors in producing low loss in a splice or termination. A fiber optic cutter is a multipurpose tool that measures the distance from the end of the protective coating to the point where the glass will be joined and precisely cuts the glass. Always remember to use a fiber trash can for pieces of glass cut from fiber cable.

When performing a fusion splice, you will need a fusion splicer, fusion splice protection sleeves, isopropyl alcohol, and stripping tools. If you are using a mechanical splice, you will need stripping tools, mechanical splices, isopropyl alcohol, and a mechanical splice assembly tool. When hand finishing a fiber you will need 99% isopropyl alcohol, epoxy / adhesive, syringe and needle, polishing film (lapping), polishing pad, polishing disc, crimping tool, stripping tools , fiber optic connectors (or splices in connectors) and piano wire.

When a termination is completed, you must inspect the end of the connector with a fiber optic inspection microscope. By ensuring that light passes through the splice or connection, a visual fault locator can be used. This equipment will fire a visible laser down the fiber cable so you can tell that there are no breaks or bad splices. If the laser light stops the fiber somewhere, the glass will most likely break at that point. When more than one light is off at the connector point, the termination was not done correctly. The light must also pass through the fusion splice, if it doesn’t, stop and re-splice or terminate.