HANDLING FIBER OPTIC CABLE
REDUCING LOSS BY PROPERHANDLINGGENERAL INSTALLATION TIPS
Like all cable, fiber optic cable must be handled properly to minimize any installation-induced signal losses (the attenuation, or deterioration, of the light signal during transmission). Of course some losses are intrinsic, or out of the installer'scontrol; these include effects from internal absorption,scattering, fiber core variations, and microbends. But extrinsic losses related to workmanship can and should be controlled; these include connections, splices, end finishes, microbends and macrobends.Installing fiber optic cables can usually be done with a minimal amount of effort if certain basic guidelines are followed.
• Always follow the manufacturer's guidelines forminimum bend radius and tension. Failure to do so may result in high attenuation and possible damage to the fiber optic cable. Guidelines are normally supplied with the cable manufacturer specification sheets. If the bend radius specifications are unknown, the industry de facto standard is to maintain aminimum radius of 20X the diameter of the fiber optic cable.
• Manufacturers may give two specifications for bothradius and tension. These are called Static and Dynamic specifications. "Dynamic" is the specification during the cable installation or while cable is under load, and "Static" is the specification for after installation is complete.
• If using tie-wraps, remember not to distort the shape of the fiber optic cable, as this adds pressure onto the optical fibers.
• Install fiber cables in a sequence that applies the least amount of strain on the cable.
• Identify fiber cable at all likely access points (ceiling access, etc.).
• Sharp bends increase cable tension, so it is best to install optic cable in sequences that minimize stress.
• Use sheaths and cable guides to maintain recommended cable bend radius.
• Monitor tension, and maintain racking bend radius.
• Protect exposed fiber cables from vehicular and public traffic.
• Prior to installation, double-check actual fiber count.
• Always follow engineering and construction placement and route plans.
• Always follow National Electrical Code guidelines, as well as local and state codes.
• Maintain good communications between installation personnel.
• When installing loose-tube cable, use a silicone injection or sealer to prevent gel migration.
• For underground installation, center-pull long cables. Store excess cable in vaults/manholes, and identify optical cables with markers.
• Aerial installation: Use proper hardware matchingcable, span and tension requirements. Use correct cable jacket.
• Buried Cable Installations: Identify cable locations with surface markers. Anticipate obstructions
PULLING FIBER LONG DISTANCES
When pulling fiber over long distances or lots of bends, use the Center Pulling technique:
1. Pull longest section into assigned duct. For long pulls, use a mid-point to evenly distribute the pulling lengthand tension.
2. From mid point, pull cable into conduit from shipping reel.
3. Remove remainder of cable from shipping reel by hand, and carefully lay into figure-eight loops one upon another.
4. Hand-feed the end of the cable into the conduit and continue pulling. Communication is necessary to assure that no damage occurs to the fiber.
For extremely long pulls, the cable can be removed at a manhole further down the installation route. Figure-eight or zigzag the cable while the pulling equipment is moved to the next manhole site.
Remember, optical cables are lightweight and very flexible, but take care not to exceed their flexibility by physical abuse of the cable.
Following these guidelines should help to make thecable installation uneventful and successful.