Before beginning installation of fiber optic cables and hardware in a premises installation, the site must be properly prepared for the installation of fiber optic cables, hardware and transmission equipment. During the design and planning stages, the site should be inspected, and all the hardware necessary for the cable plant should be included in the design.
Premises support structures
There are numerous structures used for securing fiber optic cable in premises installations, making generalizations difficult. Cable may be hung on appropriate hangers, laid in cable trays or pulled into conduit or innerduct. Termination of the cables can be at racks in telecom rooms, in wall-mounted boxes or wall outlets.
You must install support structures for fiber optic cable installations before the installation of the fiber optic cable itself. These structures should follow the guidelines of appropriate standards, such as TIA/EIA 569-A and NECA/BICSI 568-2001. Allow for future growth in the quantity and size of cables when determining the size of the pathways. Follow all cable bend radius requirements, and avoid pulling cables around hazards if possible.
Sometimes new cables can be laid in existing cable trays. To prevent damage, do not install a fiber optic cable in a conduit or duct that already contains cabling, regardless of the cable type. Existing or new empty ductwork can be modified to accept several different installations by the proper placement of innerduct.
Premises cabling requires fire stopping at all penetrations of walls and floors. Telecommunications fire stopping always must comply with applicable codes and standards. All penetrations should be protected by type-approved fire stops.
In most areas, breaching a fire separation will require physical monitoring until it has been repaired. Check with the authority having jurisdiction for requirements before commencing work.
All fiber optic equipment will require proper power at the locations of the equipment. Power must be high quality, must be protected from surges and spikes, and generally must have appropriate backup capacity to prevent loss of communications during power loss. Data equipment will require a separate ground and adequate power for year-round air conditioning. Consideration should be given to efficiency in cooling to reduce power consumption. Consult with the site owner, customer and appropriate user personnel to plan electrical power installation.
Grounding and bonding
All conductive cabling and components must be grounded and bonded. Ground systems must be designed as specified by the National Electrical Code (NEC) or other applicable codes and standards. Although most fiber optic cables are not conductive, any metallic hardware used in fiber optic cabling systems (such as wall-mounted termination boxes, racks and patch panels) must be grounded. All conductive cables require proper grounding and bonding for applicable conductors.
Marking and identifying cables
Fiber optic cables should be specified with colored jackets per industry standards, which identify the cables as fiber optic cables and indicate the type of fiber in the cable. All fiber optic cable terminations should be marked on racks or boxes where the cables terminate. Cables should be tagged with identification that they are fiber optic cables and that proper handling is required.
Particular care should be taken in premises cabling upgrades. For nearly two decades, 62.5/125 micron multimode fiber has been the primary fiber for premises cabling. With the emergence of gigabit networks, laser-optimized 50/125 fiber has become more popular. Mixing the two fibers can result in excessive loss at connections that may cause systems to not operate properly. Color coding, marking and even using incompatible connectors (SC or ST on 62.5/125 and LC on 50/125 fiber) should be used whenever possible.
Removal of abandoned cables
Unless directed by the owner or other agency that unused cables are reserved for future use and are marked accordingly, it may be required to remove abandoned optical fiber cable (cable that is not terminated at equipment other than a connector and not identified for future use with a tag) as required by the NEC or local codes.
At the discretion of the owner of the site, the contractor may be requested to remove other cables (e.g., copper communications or power cables). Removal of cables is much more time-consuming than installation, as each cable must be identified and carefully removed to prevent damaging other cables. No cable should be cut for removal unless it is positively identified.
All cables removed should be recycled properly. Most communications cable has significant scrap value, not only for any copper conductors, but for other metallic elements and even some plastics.
HAYES is a VDV writer and trainer and the president of The Fiber Optic Association. Find him at www.JimHayes.com.
(Ed Note: Part 4 is here.)