Information Technology Reference
In-Depth Information
(not just the ceiling height). The vertical drop length in the telecommunications
room should include the drop from the tray to the final termination point of the
cable, including all ducts, ports, channels, and trays through which the cable must
be routed. Be sure to accurately estimate the twists and turns the cable may make
to “dress” the wires on the mounting board or in the equipment racks.
Allow another 6 to 12 inches here for termination. If your measurements are
close to the limit, remember that cables are typically routed along the length of a patch
panel to their termination points, which might add up to 19 in of additional length.
Diagonal wire placement is really direct routing. This means that the cable is
simply run above the ceiling grid and routed directly to the workstation drop loca-
tion. Routing is done either directly over the grid or through supporting structures.
Sometimes wire hangers or clips are used, as are tie wraps.
The use of cable hangers and clips may allow a combination between orthog-
onal wire placement and diagonal placement. Bundles of cable are typically routed
through cable hangers orthogonally from the telecommunications room to groups
of work area locations, but individual work area drop cables may be diagonally
routed from the nearest hanger.
Older buildings, houses, or buildings with fixed ceilings present special problems
to cable routing. Often the cables may be run in an attic or crawl spaces. Sometimes
cable must be run around baseboards or even over door frames to reach the worksta-
tion location. The use of staples—a common mounting technique for telephone wires—
is definitely out, even for Category 3 cable. Be careful when estimating cable lengths for
these buildings. Simple detours, such as doorways, can eat up lots of cable. For exam-
ple, a 10 by 20 ft room would require 10
20
17
47 ft of cable simply to run to
an opposite corner of the room, if one 7 by 3 ft (7
3) doorway has to be tra-
versed. If a drop must be run through several adjacent rooms to reach from the wiring
closet to the work area, an enormous amount of cable may be required.
7
Accessibility and Appearance
The wiring centers of your network are key components of your LAN system, con-
taining important networking hardware, the cable distribution points for your
users, and important diagnostic and backup equipment. In addition, many impor-
tant installation, configuration, and troubleshooting tasks take place there. For
those reasons, you should devote the time and money necessary to maintain good
telecommunications rooms and equipment rooms.
The first key to a good telecommunications room is accessibility. The wiring
connections and network hardware should have their own room, out of the way and
yet easy to get to. The area should be as close to the work areas as possible, since
