The old adage, “You get what you pay for” applies to most purchases that you make in life. Fiber optic cleavers are no exception!
Before we begin to dive into that question let’s get a brief understanding on what a fusion splicer is. If you are in the fiber optic world you will definitely know what a fusion splicer is and most likely will have used one or will be using one. A fusion splicer is a machine that fuses or welds two different pieces of fiber optic glass cables together to become one with an electric current also known as an arc. Most fusion splicers have an attached shrink oven that the protection sleeve is placed into to complete the process. Some splicers do not have an attached shrink oven and an external separate shrink oven will be needed for the application. As mentioned, fiber optic cable is made of glass and glass, especially how thin optical fiber is, will be very brittle and can very easily break. When this fusion of glass is completed, this is where our friend, the fusion protection sleeve steps in.
You may be asking, what is a fusion splice protection sleeve? Well that is a great question! A fusion protection sleeve is used to protect the fusion splice where the two separate pieces of fiber optic cable have been joined into one. A protection sleeve is made up of three parts: An outer shrinkable tube made of heat shrink plastic, an inner tube or fiber tube where the fiber is placed, and a strength member, either made of stainless steel or ceramic, more on this later. The protection sleeve ensures a consistent and reliable means of protection of the fiber when heat is applied from the splicer oven or external oven. Have you ever broke an arm or bone or knew someone who has? When this happens a cast is applied to the broken area. The cast can be interpreted as the protection sleeve and the broken bone area is the fiber optic cable. The cast protects the broken bone as the protection sleeve protects the fused fiber cable.
Fusion protection sleeves can be broken down into basically two categories: single splice protection sleeves and ribbon splice protection sleeves and will most commonly be 40mm or 60mm in length and are normally made of a clear outer tube so you can view the fiber when inside the sleeve for regular inspection and/or maintenance to the cable inside. A single splice protection sleeve is just that, a sleeve that will accommodate a single piece of fused fiber. A ribbon splice sleeve can accommodate multiple fiber splices ranging from 2-12 fibers inside the sleeve. As mentioned above, protection sleeves will either have a stainless steel or ceramic strength member that runs the entire length on the side of the protection sleeve and there is a definitive reason there are two different types of strength members. Fiber optic cable uses light to transmit data and light and glass to not conduct electricity. If a contractor is specifically using fiber optic cable in the application there should be no worry in using a protection sleeve that contains a stainless steel strength member. On the other hand if the fiber optic application will be next to or near any copper/conductive type material, the contractor may consider a splice sleeve that contains the ceramic strength member so there is no electrical disturbance between the copper cable or conductive material and the strength member.
Before the splice sleeve is applied to the fusion splice and the cable, the splice sleeve itself should be inspected before installation. This is done to ensure the sleeve is free from deformity and is clean both on the outside and the inside of the sleeve. The inspection and cleaning process is vital in any fiber optic application ranging from cleaning connector ends to making sure your equipment is clean from any contaminants. Not cleaning your fiber optic accessories and equipment is the leading cause of attenuation in the cable. Attenuation is the measurable loss of signal strength along the cable and it is measured in decibels. Inspecting the inside of the sleeve to make sure it is free of contaminates along with cleaning the fiber before installing the sleeve is a good practice as the slightest bit of contaminates could and most likely will cause attenuation. When not using the sleeves, they should be stored in a clean plastic zip bag for protection during storage.
Aside from the importance of cleaning there are other factors to consider before your splice sleeve installation. As mentioned earlier, protection sleeves are used when fusion splicing. Your fusion splicer has many different settings that can be chosen when splicing and may differ from manufacturer to manufacturer. Fiber tension is one setting that may need to be adjusted in this process. Improper fiber tension can result in an improper or uneven shrink when the protection sleeve is placed in the shrink oven. It is essential to maintain proper tension on the cable and not to twist the fiber when placing in and removing from the oven.
Another factor to consider in this process is actually the type of cable you’re using to splice with. Some fiber optic cables contain a gel similar to petroleum jelly that is contained on the inside jacket of the fiber. This gel will need to be cleaned off of the cable with a special degreaser wipe to ensure the proper fit and finish of the application of the splice sleeve. Inspecting the splice sleeve after it is removed from the heating oven is another good practice as the heat setting may be to high resulting in a split in the sleeve itself or the heat may be to low resulting in an improper shrink to the sleeve. If either of these are observed you may need to adjust the heat setting on the oven itself.
Once all of these installation practices are meet, the protection sleeve along with the attached cable are usually placed in a splice tray. A splice tray is a tray or container that prevents spliced fibers from being damaged or misplaced after splicing. If the cable and protection sleeve will be placed in a splice tray the protection sleeve should have the strength member pointing down, you should not be able to see the strength member when looking at a protection sleeve when it is in a splice tray.
As small as the fusion protection sleeve may be, it is a huge importance to the fusion splicing world of fiber optics. When all of these practices are met, you will be successful when you decide to try your hand at fusion splicing with the added protection of fusion protection sleeves added to your fiber optic cable installation arsenal.
When looking at terminating fiber optic connectors for a job there are several factors that are taken into account to help decide which way is best. There are field polish connectors in which some form of epoxy (glue) is used to hold the fiber in place. With this one, you have to polish it in the field as well which if you haven’t ever done it, can be very difficult. There are also factory polished style connectors that can be mechanical connectors, pigtails, splice on connectors or pre-terminated cable assemblies. The mechanical connectors have a piece of fiber already in them and you just have to align your field fiber up to the fiber inside the back of the connector. This can be difficult or take some time to master. A fiber pigtail consists of a piece of fiber optic cable that has a connector on one side and no connector on the other side. These can either be fusion spliced to another piece of fiber, or run through conduit and terminated at the other end. The alternate solution would be to have your cable assemblies built to the length that is needed with optical connectors already installed on them in a factory setting. Let’s look at some different qualities to see how this will be beneficial.
All connectors whether installed in the field or in a factory have to be polished in order to work properly and get the end result of passing a signal over the fiber optic cable. So let’s look at the two different ways to polish. First, you can always hand polish a connector. In this process, you will use a polish puck, rubber durometer pad and a glass plate along with polish film to achieve a suitable connector endface. There are some technicians that have been doing this for a long time and could get close to a perfect polish on the ferrule endface. Not everyone can do a good hand polish. There are several factors that come into play and can cause various results on your finished optical connectors such as the amount of pressure applied while doing your figure 8 on the polish paper. When in a dusty area debris can get on the polish film, causing a connector to be ruined. See how little things in this process can affect the end of the connector and how long it takes to get a good connector? If a connector is bad due to being over polished, pitted or even shattered you will have to repeat the whole process.
On the other hand a factory polish is finished using a polish machine in a manufacturing facility. The amount of pressure is the same. Polish machines have holders that allow many connectors to be polished at once to save time. The procedures used have been honed over time to be the most efficient which helps to produce high quality polishes. In a factory all connectors are checked to a higher standard and are not allowed to be shipped until checked by quality control where they will be scoped and tested. This gives each and every factory connector a perfect outcome.
Plug & Play
When getting factory terminated fiber optic cable assemblies cut to length you are providing yourself with the simple concept of plug and play. This means all you have to do is run your link and then just plug the connectors into your rack, switch or connection point. This not only saves time on your cable installation but also will save you in labor and installation costs. Plug and play is not always a possibility due to restrictions in conduit size or the number of bends that are required to go through. We get that and that is why there are several ways that a connector can be put on a cable. All we are saying is, imagine if you get a house hold item such as a toaster; would you rather take the toaster out of the box, plug it into an outlet and have toast in a matter of minutes? On the opposite side; would you like to get a toaster that does not have a cord and you have to go find all the tools that are needed? Now you have to refresh yourself on how to strip a power cord so you can put a plug on one end. Then you have to open the toaster and get your other end prepped. Point being, we all like to just pull things out of the box, plug them in and away we go.
What is easier than getting a cable that has all the connectors on it and a way to pull it in place? Essentially this is what you have with a pulling eye installed. All a pulling eye is, is a loop that is connected to the Kevlar of a cable assembly. Why the Kevlar? Kevlar, when you have multiple pieces stranded together is not only strong but almost impossible to break. It does not stretch when pulled on and it keeps the fiber cable from stretching. We have had instances when cable has not been pulled by the Kevlar, instead pulling on the jacket of the fiber. The jacket of the cable will stretch and eventually with too much pressure it will break. Also, when a jacket is pulled, when released you get what is called a growing effect of the fiber. Meaning it looks like kids through their growth spurts. The jacket after being released shrinks to try and get back to its original form. When this happens the fibers that are inside will come out the end making it look like your fiber is extending. Not only is this bad for the jacket that protects the fibers but it can also cause breaks in your cable that will not be realized until it is tested. So when pulling fiber cable, always make sure you are pulling correctly using the Kevlar. It’s better to just have a pulling eye installed and save yourself a huge headache.
Higher Overall Quality
When looking at fiber optic connectors there are several factors to consider. Looking above at all the advantages of a factory polish termination along with pulling eyes, you can see how it can save you money and time to go with the factory built cables. Now if you do have to install connectors in the field, the alternative would be to get connectors that are already factory polished such as the ones on a fiber pigtail used when fusion splicing. When doing a job, no one is purposely trying to have bad connectors. Factory polished connectors whether they are pigtails, mechanical connectors or pre-terminated fibers all have the high quality that you will need to show your customer that you take pride in the work you do and want to use the best possible connectors available. Nothing is better than a connector that is polished by a machine, and then put through a rigorous testing phase before they can be considered done and ready.
There are several parts that make up a fiber optic cable; starting with the core, to the cladding, followed by the coating, the strength member and lastly the outer jacket. The outer jacket is the cover that gives protection and shielding, especially to the optical fibers. Whether it is meant to be indoor/outdoor, UV rated or armored, the jacket is what keeps the fiber protected and useful. Above all of these, the outer jacket is the first layer of protection to the fiber so it can withstand different conditions such as fire, moisture, chemicals, and stress during installations and maneuvering.
The National Electrical Code (NEC) has a classification system for optical fiber cables. The system specifies the requirements regarding how the fiber cables will endure under fire conditions. These requirements concentrate on how these cables can add a dangerous amount of fuel and smoke and transmit fire from one place to another.
OFNP – Optical Fiber Non-conductive Plenum – refers to the specific fire code rating of cable that is flame resistant and emits the least toxic fumes or smoke when burned. Plenum rated cables have a higher fire rating and are for both commercial and residential use. They are considered the safest rated cable among jacket types. These cables are primarily used in ducts or pathways for heated and cooled return airflows. These spaces are usually above a ceiling or below a floor that serves as heated or cooled inhabited areas.
Plenum cables are purposely built with a jacket that gives off low amounts of smoke and that is flame retardant. Being able to deter the spread of flames and toxic fumes are the main uses for this jacket rating. The word plenum refers to the space in which air is circulated by a HVAC system. Drop ceilings and raised floors are perfect for the application. Plenum cables still use PVC (Polyvinyl Chloride) in the construction of the plenum jacket but special additives are put into the jacket material in order to make it more flame retardant. The NEC defines plenum cables by the airspace they are put into. Plenum rated cables are often used in building construction, typically they are used as communication cables for the building’s computer and telephone networks. Use of plenum areas for cable does pose some hazard in the event of a fire. This is because there are fewer barriers to contain smoke and flames.
OFNR – Optical Fiber Non-conductive Riser – is constructed of PVC and will emit toxic fumes when burned. Riser cables are to be run only in non-plenum areas. Plenum can usually replace riser but riser cannot replace plenum. Riser rated cables are typically used in the riser areas of buildings and in vertical telecommunications infrastructures. They connect from one floor to another and are used within shafts in accordance with section 800.53(B) of the NEC (National Electrical Code). They typically have load bearing strength members since they need to be upright without placing added stress on the fiber.
OFNR cable is resistant to oxidation and degradation but still gives off heavy black smoke and toxic gases when it is burned. Yet it is perfectly fine to use as a patch cord or for single in-wall runs. If you want to use it in a building, the building must feature a contained ventilation system and have good fire exits. Location is extremely important for these types of cables.
LSZH – Low Smoke Zero Halogen
These types of cables are made with halogen free materials and although they still emit smoke it is a much safer alternative. This type of cable jacket has superior safety characteristics. This rating offers low smoke, low toxicity and low corrosion standards. Tunnels, enclosed rooms, aircraft, and other minimum-ventilation areas are prime spots for the use of LSZH cables because areas like these are more difficult to escape from quickly. There are many different types of LSZH jacketed fiber optic cables provided for many different uses. The primary use for these types of cables is to satisfy the need for safety and environmental protection. Hospitals, schools and airports are good examples of where these cables should be installed. Due to the amount of people and the serious need for the protection of those people and equipment from toxic matter and gases should a fire ever occur. These cables are especially popular outside the United States, specifically for plenum spaces. Although it may seem as if you can replace plenum with LSZH cables, that’s not really the case. The difference is that while there is a lower smoke rating for LSZH, plenum cables have higher fire spread rating.
Cable tray rated
Tray cables are designed for just that, installation in cable trays. Primarily they are used in industrial control systems, factories, wind turbines and other severe environments. They can be rated for use indoors, outdoors, and in corrosive areas, for hazardous locations or high electrical noise areas. This cable was first introduced in order to combat failures in power and communication applications. There are several different kinds of cables to choose from, these include: Tray Cable (TC), Power Limited Tray Cable (PLTC), Instrumentation Tray Cable (ITC), Exposed Run (ER), and Wind Turbine Tray Cable (WTTC). Effective in direct sunlight as well as underground, these types of cables are extremely versatile in their application. Although cable in tray is viewed as being exposed to a greater risk of mechanical damage and it can be a potential ignition source or fuel load in a fire scenario. Due to this the NEC has a specific requirement in order to ensure the safety and quality of these fiber runs.
When choosing a jacket rating it is important to understand the placement and application where the cables will be run. It is pivotal that the cables meet local code requirements for the installations as well. These ratings are designed to prevent hazards and reduce risks to human and environmental health. We put on a jacket to prevent uncertainties from happening to our body, such as a cold or the flu. Fiber optic cable jacketing is very similar in the sense that we apply a certain compound to prevent a dangerous mishap, or if it does happen in the environment of the application.
Winter is coming… be sure to put on the appropriate jacket! .