From the outside, a fibre-optic cable usually looks similar to any copper-wire cable, but what is inside the sheath can be very different. Cabling installers are often called for laying them hence it is important that they understand the differences between copper and glass. They need to develop suitable installation procedures for this new medium.
General cabling guidelines
Wherever you intend to install optical-fibre cable, you need to follow certain basic guidelines with the help of cable clamp factory.
- You need to support these cables with fiber cable clamp to avoid stressing, crushing and overbending it. All cables will have certain minimum values for bend radius and the maximum values for tensile loading, which should not be exceeded. Never allow the cables for long distances to hang freely or press against the edges during the installation.
- All the transition points, e.g. those going to pull box from conduit or those exiting the conduit, must be maintained smooth while pulling any cable inside the conduit.
- To prevent pressure against any cable or rubbing on the rough edges, flexible conduit may be placed at interfaces or within boxes. Such flexible conduit may also be added, which are going to be frequently accessed, e.g. raised computer-room floors, as there can be higher risk on the cable.
- In case of rack and tray installations, it is necessary to monitor minimum bend radius, as the cable can be routed either through transitions or around corners. Where rack transitions or raceway expose the cable, use of flexible conduit with fiber optic cable clamp is necessary for shielding.
Following are guidelines to be observed for horizontal cabling for optical fibre cabling:
- Intrabuilding conduit may run on walls, ceilings or under floors, though there are few limits as conduit systems are quite inflexible. Such systems must be used only where there are permanent workstation outlet locations and where there is no need of any wiring flexibility and having low outlet density. Such in-floor conduits are usually embedded in concrete hence it is difficult to make any adds, moves and changes. According to National Electrical Code, any conduit can be either of metal tubing or any rigid polyvinyl-chloride plastic.
- Conduit runs must be within 100 feet, with maximum two 90-degree bends in between boxes or pull points.
Cable in trays
Any cable in trays can provide a very safe, convenient and efficient location where optical-fibre cables are to be installed. Trays can either be installed in the ceilings or below floors or in riser shafts. Certain trays are so designed that it is quite pleasing aesthetically, so they may be placed under the ceiling within the vision.
Although any tray can provide sturdy support and minimum cable protection, there can still be stresses to which such cable can be subjected. Any optical-fibre cable must always be run within trays for avoiding as much tension, bending and crushing as possible.
The same advice also holds true for adds and moves. To avoid any damage during changes, it is necessary to secure the cable with the tray.