Information Technology Reference
In-Depth Information
patch cords are not yet installed in the TC, you might consider testing the channel
using the actual extended user cord and the 5 m maximum equipment/patch cord.
Fiber-Optic Cabling in Open Offices
No discussion of the shortcomings of twisted-pair cabling would be complete with-
out mentioning fiber-optic cabling. Most of the problems with copper cabling occur
at the points of termination and interconnection. This is the place where the imped-
ance mismatches, untwist, NEXT, and FEXT occur. The only similar problem for
fiber is the introduction of a very small additional attenuation and mismatch that
occurs at a termination. In a typical fiber-optic link, there is plenty of margin for a
small transition attenuation.
For that reason, the only structured cabling limitation placed on fiber optics
for open-office use is that the total length of cables and patch cords may not exceed
the 100 m (328 ft) limit that is otherwise stated in the standard. With a typical con-
nector loss of about 0.2 dB, you can add a lot of terminations, patches, and splices
with little or no effect at only 100 m.
In addition, you can use the TSB-72 guidelines for length if you are connecting
open-office workstations using a centralized fiber network scheme. Consult Chapter
11 for more information on fiber cabling.
Fiber-Optic MUTOA Cabling
Fiber-optic cabling in the open office is always considered to be the multiuser out-
let method. Fiber cabling does not use the punchdown method of copper wire, and
thus cannot use the consolidation point method. However, there are still several
important considerations for using fiber with open offices.
Fiber-optic cable must be very carefully managed, to prevent any possible dam-
age to the fiber during and after installation. At the MUTOA, the fiber cable will
have to be separated out to individual fibers and each terminated in a fiber connec-
tor. At this stage, the fibers are tiny, relatively unprotected jacketed strands that are
highly susceptible to damage. An enclosure, such as a fiber termination tray, is the
best way to deal with this problem.
The best fiber termination enclosures are the same ones that are used in the TR.
Smaller versions are available for use with multiuser distribution points. In very lim-
ited modular furniture terminations, it may be possible to use some of the innova-
tive multiple connector outlet boxes that are designed to terminate from four to
eight fiber pairs. These outlet boxes are designed to contain the extra lengths of
unjacketed fiber strands that are required at the point of termination. They are often
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