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 MIL-HDBK-1012/3
3 m (10 ft.) at each end of the cable will provide sufficient
cable for sweeping bends, splicing, or termination. NFPA 70
prohibits running outside rated cable farther than 16.5 m
(50 ft.) within a building unless it is in rigid conduit.
Additional information regarding service entrances is included in
par. 1.9.1. An additional cable length equal to 3/4 of the
manhole perimeter measurement for each manhole in the pathway
should be added to the overall cable segment length total. Since
it is extremely difficult to ensure cable paths and reel lengths
exactly, it is common practice to add 10 percent to the total
cable estimate. When installing fiber optic cable, it is
recommended that 8.2 m to 16.5 m ( 25 ft. to 50 ft.) of fiber
cable be coiled in every other manhole along a pathway to provide
slack for emergency repair splicing.
e) Warning: Prior to initiating any trenching or
plowing for conduit placement, the local Public Works Office,
CATV company, and commercial Miss Utility must be notified to
identify and locate other utility services located in the
installation area. The other services can be in the form of
buried gas or water lines, power cables, CATV lines, etc. It can
be advantageous to the RCDD and subsequent installation activity
if the routing of other services within the area is identified
and marked during the site survey process and again just prior to
installation activity. Chapter 15 of the BICSI Manual provides
recommended minimum space requirements between telecommunication
cabling and utility services.
1.8.4.3
Tunnel. The criteria for the type, size of cable, and
mechanical placement requirements of backbone cabling in a tunnel
is similar to that identified in the underground system described
in par. 1.8.4.2 above. The engineering and estimating factors to
be considered when routing backbone cable through a tunnel are:
a) Physical separation between backbone cables and
high or low voltage power cables must be at least 310 mm (12 in.)
parallel, 103 mm (4 in.) crossing;
b) Physical separation between backbone cables and
water, steam, or gas piping shall be at least 310 mm (12 in.)
parallel and 155 mm (6 in.) crossing;
c) Racking methods and techniques for cable routing
and splice cases;
d) Tunnel access for personnel and material, crossing
points and corners;
e)
Requirements for conduits;
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