Information Technology Reference
In-Depth Information
Combination cables are available that contain both optical fibers and metallic
conductors. These cables may be offered with shielding for the wires. See the section on
UTP and STP cable for a complete discussion of shielding types for these conductors.
If you intend to place LAN cable outside of ordinary office locations, you may need
to specify special purpose cable types. Most normal locations for LAN cable are
benign environments that maintain the cable at mild temperatures, away from mois-
ture, contaminants, harsh or dangerous chemicals, and the effects of the sun.
However, many locations exist that require special wire insulation, jacketing, armor-
ing, or ratings. Most wire types are available in special versions to accommodate all
of these needs. Several of these special-use ratings for cables are described here.
Plenum and Riser Rating
Cables that are placed in plenums must be plenum rated (Fig. 5.8). A plenum is a
space used to move air to workspaces for the purpose of ventilation, heating, or
cooling (HVAC systems). The informal words for plenums are “air duct” and “air
FIGURE 5.8
Cable markings for special use ratings.
