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Planning a Pathway
Cabling shouldn't just be stuffed into the ceiling, looking like a tangled spider's web. To meet electrical codes so that your cable plant is warrantable (as well as making it pretty), cabling pathways need to be designed systematically. This is where your BICSI and RCDD LAN specialists can be invaluable. They work with the other building contractors to find a safe place to run the cable. In most buildings, cable contractors have the last priority in overhead space. They almost always come after the electrician and HVAC folks. If involved early enough in the game, however, the wiring contractor can share the overhead space harmoniously with the other building systems during the construction phase.
There are two ways to deliver the cable from the computer room to the stations:
Cable tray. This wire basket is mounted to the structural steel of the building to hold large volumes of cable. This method is secure but expensive.
J hooks. These large hooks are placed on every beam (approximately four feet apart), providing good support to the cable bundles without letting it sag too much. This method is inexpensive but not as secure as using cable tray.
We went with cable tray above the computer room and J hooks out to the various stations. We have more than 600 cables coming into the computer room, and like the support of the wire baskets to hold the weight of the cable before final delivery to the patch panels. Four-position J hooks were installed along primary pathways (main hallways), like a vehicular highway. Double- and single-position J hooks were then needed on the "side streets" to deliver several individual cables to each station.
Picture this: Our computer room is in the middle of a large rectangular building. The shape of the cable pathways is a giant letter H with the main legs of the H running down primary east and west hallways to the north and south of the computer room, and the center portion of the H going over the top of the computer room. A single cable would go out the north wall of the computer room and turn right to serve a station on the northeast corner of the building, and so on for other parts of the building.
To provide maximum bandwidth and to prolong the life of the cables, it's important that the cables don't get pinched or severely bent, or have their sleeves nicked. To provide that stability, wires are usually bundled with hook-and-loop fastener straps. This is preferred over zip ties, as ties tend to dig into the cable sheathing.