Information Technology Reference
In-Depth Information
FIGURE 5.9
Outside plant cable (built with steel “messenger” cable bonded to the top of the data cable).
stringent requirements on cable of any type. Outside cable is suspended long aerial
distances, run in underground cable ducts, and directly buried. Cable may need to
be gel-filled or pressurized to exclude moisture. It may need special strength mem-
bers of an integral messenger cable to span aerial distances. Metallic armoring may
be needed to resist damage from animals.
If you must run outside cables into buildings, you may want to consider a cable
that is also rated for indoor use. Such cable meets the
NEC
code requirements for
indoor use as well as being designed for the harsher outside environment. The
NEC
specifies that typical outdoor cable may only be extended 50 feet inside a building,
unless that cable is rated for the proposed indoor use. The alternative is to place a
junction or splice point inside the building, near the point of cable entry, to convert
to inside-rated cable.
Hazardous Locations
Special cable, conduit, and junction boxes may be required for cable that is run in
so-called hazardous locations, including places where flammable or explosive gases
or liquids might be present. Surprisingly, hydrogen and oxygen gas fit into this
description, as do volatile liquids such as gasoline and solvents. The
NEC
addresses
the installation of cabling in hazardous areas.
