Brian Reed, Mod-Tap
Problem
When installing an unshielded or shielded twisted-pair cabling system in any environment, some general installation practices must be observed concerning placement of cable and cable support. Lack of attention to these commonly accepted guidelines can result in expensive re-cabling projects. For example, electrical interference, cable droppage and signal loss can result when copper twisted-pair cable is improperly installed.
Solution
Develop and implement standard procedures for placement and support of cabling runs. These procedures can eliminate common problems and ease future maintenance.
Procedure
1) Ensure cable enters and exits major run areas at 90 angles while adhering to bend radius specifications, where applicable. By providing easier access and making run locations more predictable, this simplifies maintenance of installed cable plant. Design major cable-run pathways to follow corridors or run parallel and perpendicular to corridors with a minimum of corridor crossovers. To minimize disruption to customer personnel during installation and maintenance, do not run pathways point-to-point over offices.
2) Support any cabling that runs in open-access environments every 4 to 5 feet to protect cable bundles from undue stress resulting from their own weight. In addition, use cable supports, trays or wireways of suitable design to hold cables permanently.
Note: Never support cable by attaching it to the ceiling support system in ceiling plenum environments.
3) Make sure cables are free of tension at both ends, as well as over the entire length of the run.
4) Install cable runs so that they are free of bridges, taps or splices between the distribution frame and the wall plate.
Note: One exception to this rule is during the installation of Ethernet 10Base-2 coaxial cable (Thinnet), which requires that the connection to the terminals use tee taps.
When routing cable, maintain the following minimum distances from power sources:
- Six inches from power lines of 2 kilovolt-amperes or less
- One foot from high-voltage lighting, including fluorescent
- One yard from power lines of 5 kVA or greater
- 3.5 feet from transformers and motors
Brian Reed is the KATT Premises Distribution System product manager at Mod-Tap, Harvard, MA.
