c) Cable bundles should not be tightly wrapped or so
large that the weight causes excessive stress on the bottom
cables. The size of the bundles will normally be dependent upon
the fill ratio of the duct being used or in the case of ceiling
installations, ceiling bundles are usually limited to 55 when
supported by 103 mm (4 in.) rings. Slack must be taken out of
the bundles prior to wrapping them. Cable ties or wraps used in
air plenums must be plenum rated. Cable wraps made of Velcro
type material are available and help the installer avoid cinching
cable bunches too tightly. Figure 14 illustrates how to
determine the length of cable tie or wrap to use. Cables are to
be homerun without the use of bridge taps which create multiple
appearances. Bridge taps are expressly prohibited by FIPS 174.
Cables installed in ceilings must maintain a 155 mm to 310 mm
(6 in. to 12 in.) clearance above the false ceiling supports.
Cables should be labeled at both ends in accordance with an
approved cable management system as outlined in EIA/TIA 606,
Administration Standard for the Telecommunications Infrastructure
of Commercial Buildings. A convenient list of do's and don'ts
for CAT 5 installation and termination, developed by the 504th
Signal Battalion, is included as Appendix A.
Termination. Care must be taken during the termination
phase to ensure that proper hardware and workmanship are applied
to the effort. Never untwist CAT 5 cable more than 16 mm
(1/2 in.) when terminating it. Installers require specific
training and certification by a qualified instructor prior to
attempting the termination of CAT 5 or fiber optic cables to
maintain the integrity of the system design. Numerous
manufacturers of CAT 5 cabling systems provide a 15-year warranty
on their products but require that the installer be certified by
that manufacturer as a qualified installer.
CAT 3 and 5 Terminations. The connecting hardware must
be rated as high as the cable being installed. Insulation
displacement type connectors should be used. The installation
criteria for CAT 3 systems is identical to those specified for
CAT 5 with the exception that CAT 3 cable may be untwisted 27 mm
(1 in.) vice 16 mm (1/2 in.). Other practices should remain the
same since it is likely that both categories will be pulled
together and terminated in the same wall box to serve collocated
voice and data jacks.