Specifications

24
Black Box Guide to Structured Cabling
Section NameSection Name
Structured Cabling System
Simply put, a pathway is the space in which
cable runs from one area to another. The standard
TIA/EIA-569-B: Commercial Building Standard for
Telecommunications Pathways and Spaces defines
different types of pathways, such as interbuilding,
intrabuilding, horizontal, service entry, etc.
This discussion will cover intrabuilding backbone
and horizontal pathways. Interbuilding and service
entry pathways are beyond the scope of this guide.
Intrabuilding backbone pathways.
Intrabuilding backbone pathways run vertically
and horizontally between the entrance facilities,
equipment room, and telecommunications room(s).
They carry the backbone cable and can be conduit,
sleeves, slots, or cable trays. Complete specifications
for conduit, sleeves, trays, pull points, and more can
be found in the TIA standard.
NOTE: Make sure all pathways are firestopped.
And, do not use elevator shafts as backbone pathways.
Vertical backbone pathways. When designing
a building, stack the telecommunications rooms
vertically above one another on each floor. This
provides for the easiest and most efficient backbone
runs. The TRs should have a minimum of three 4-inch
sleeves for floor areas of 5000 m
2
(58,819 ft.
2
). One
sleeve is for the cable; the other two are spares.
Horizontal backbone pathways. If the TRs are not
stacked vertically, use 4-inch conduit to connect them
horizontally. You should have no more than two 90°
bends between pull points. In addition, the fill should
not exceed 40% for any run greater than two cables.
Horizontal pathways.
As the name suggests, these pathways run
horizontally between the telecommunications room
and the work area. You can choose a number of
different pathways, depending on your facility, office
layout, and cable type. When choosing, keep in mind
the pathway fill for current and future use, and allow
enough room for growth.
Pathway options.
Underfloor duct. These are a system of single- or
dual-level, rectangular ducts embedded in concrete
flooring that’s at least 64-mm (2.5-in.) or 100-mm
(3.9 in.) deep, respectively.
Flush duct. This is a single-level, rectangular duct
embedded flush with the top level of a 25-mm (1-in.)
concrete surface.
Multichannel raceway. Ducts have separate
channels for running telecommunications and power
cable. The raceways are designed to be buried in
75-mm (3-in.) reinforced concrete.
Pathways
Building Pathways
Backbone pathways
Equipment
room
Telecommunications room
Work area
Entrance facility
Horizontal pathways