Cable trays and ladder racks are convenient, safe, and efficient locations for installing optical-fiber cable. While they can be installed in ceilings, below floors, or in riser shafts, there are trays designed to be aesthetically pleasing, allowing them to be placed in the line of vision. Since trays can be used for many types of cable, installation precedes pulling the fiber cable. This means that existing tray distribution systems may be used for installing new cable if the system supports the appropriate locations.
Even though a tray provides support and protection for cable, the cable is still subject to stresses, which is why optical-fiber cable should be run in trays to avoid as much tension, crushing, and bending as possible. You should inspect routes for sharp turns, snags (even from other cables), or rough surfaces. You should run the fiber cable without pulling it under or between heavier cable and multiple cables that can stress the cable.
This also goes for moving or adding cable; the cable should be secured to the tray and attached at least every three feet to avoid damage when changes are made.
You should apply the same guidelines when installing cable in vertical shafts or risers, using only cable rated OFNR, at a minimum. Optical-fiber cables for vertical applications are assigned a calculated maximum vertical rise, which is the distance the cable may be pulled vertically before they are supported, determined by the weight of the cable and its ability to resist buckling or kinking.
In order to pull cable vertically, you should use split wire mesh grips, which work like basket or finger grips to support the cable without crushing its core. The cables should then be supported by cable ties, straps, or clamps in wiring closets, and you should begin the installation from the top whenever possible, to allow the weight of the cable rather than adding more load.
Handling procedures vary from product to product, so you should abide by specific handling procedures in the manufacturer’s instructions However, some general observations can be made on the situations most often encountered in pulling and terminating this medium.
For any fiber-count cable or cable type, some of the outer jacket must be removed to expose the fibers. For simplex or duplex cables whose jackets fit within the connector, the length of jacket removed will be specified by the connector manufacturer. Typical values for outer jacket removal for these cables are 1.5 to 2 inches. Multi-fiber cables will have longer lengths of jacket removed. Outside-plant cables that will be terminated in trays may have more than six feet of jacket removed. Mark the cable with a piece of tape to show how far the jacket should be stripped.
Interconnect Cables: For simplex and duplex cables, no more than a few inches are removed from the point of termination, which can be easily done with a standard buffer or jacket strippers. For round interconnect cable jackets, round cable slitters or other tools can be used, so long as they do not damage the interior of the core.
Distribution Cables: Provided with ripcords for easier jacket removal, distribution cables may have dual ripcords for higher fiber-count unitized cables, requiring only the first few inches of the jacket to be removed. The ripcord can be exposed by removing the first four inches of jacket with a cable slitter or a hook knife, then you can grasp the cable end with one hand and use the other to pull the ripcords one at a time.
Heavy-Duty Breakout-Style Cables: All heavy-duty cables contain dual ripcords for jacket stripping and clear polyester tape wraps to maintain core symmetry and fiber protection. Once several inches of jacket have been taken off, the ripcords can be used.
Outside-Plant Cables: Outside-plant cables have ripcords and core wraps to aid in the removal of the rugged outer jacket, but use caution and don’t get the aramid strength members tangled with the ripcords.
You can cut the clear tape and ripcords can be cut back to the jacket after it has been removed to the required distance. In cables that have layers of aramid in the core – for example, interconnect and low-fiber-count distribution-style – trim the aramid to the necessary length as specified by the manufacturer. Aramid is most easily cut with utensils sold specifically for the purpose, although razor blades and scissors do work.
Central strength members must also be trimmed, with some cut back to the jacket so as to not interfere with termination, and other applications calling for the central strength member to be cut to a specific length and incorporated in termination (for example, in some breakout kits).
Central strength members that are made of fiberglass rod can be cut with almost any cutting tool, though those with aramid inners are more easily cut with aramid cutters. Unitized distribution cables contain aramid yard and jackets over the subunit, which must be cut back. This is why it may be easier to complete installation of a 6 or 12 fiber subunit at a time in order to avoid connecting the wrong fiber to the wrong termination point.
Buffer-tube cutters are designed specifically for the purposed of easy buffer-tube removal, but it can also be done with a razor blade. Score one side of the tube with the razor and bend the tube away from the score. As long as you don’t cut too deeply, the separated piece can be pulled off the end of the fiber.
There are many tools that can strip the buffer and coating off 900-micron tight-buffered fibers or the coating off loose-buffered fibers, with tight-buffered fibers being stripped in a one- or two-step process, depending on the tools you have. Taking the coating off loose-tube fibers can be done with the same tool used for the coating of tight-buffered fibers, and with some tools, the blades can be exchanged for the two functions.
The amount of buffer or coating you need to remove depends on the application and termination procedure. Many connectors will come with templates for this purpose, so be sure to check the hardware or connector manufacturer`s specific instructions for a detailed procedure.
For the removal of cable-filling gel, try Hydrasol solvent. Any gel remover used carelessly can mar the tube printing, but Hydrasol, used in moderation, will not affect the identification markings.