Information Technology Reference
In-Depth Information
TABLE 5.7
National Electrical Code
®
(
NEC
®
) Cable-Use Codes for Fiber Optic Cable
NEC
article
Code
Meaning
Allowable Substitutions*
770
OFNP
Optical Fiber Plenum
none
Nonconductive
OFNR
Optical Fiber Riser
OFNP
Nonconductive
OFNG
Optical Fiber
OFNR
OFN
Nonconductive
General purpose
OFCP
Optical Fiber Plenum
OFNP
Conductive
OFCR
Optical Fiber Riser
OFCP OFNR
Conductive
OFCG
Optical Fiber
OFNR OFCR OFN
OFC Conductive
General purpose
*In general, a cable with a more strict usage code may be substituted in an application that allows a less strict
usage code. For example, a cable rated to the stricter plenum code may be substituted in a riser application. The
chart does not list all possible substitutions, only those to the next level. A nonconductive cable is one that con-
tains no metallic elements, including conductors, metallic sheaths, or strength members.
Source: 1999
NEC
®
.
Fiber-Optic Color Coding and Marking
Fiber-optic cables are generally colored black for outdoor use. For indoor use, a
variety of colors are available. You may wish to choose a bright color to distinguish
the fiber-optic cable from other cable. Fiber-optic jumpers are often bright orange
or yellow. The glass fiber may be damaged by tight bending or sudden impacts and
is easier to avoid when it is brightly colored.
Marking is the same for fiber-optic cable as for conventional metallic cable.
The marking will generally include the name of the manufacturer, the manufac-
turer's part number, the
NEC
or UL rating (or similar rating for the country of use),
and perhaps the fiber size (such as 62.5/125) and mode.
Fiber-Optic Shielding and Armoring
Fiber-optic cables transmit light and do not need to be shielded from electromag-
netic fields. Some cables are armored or include a wire strength member for aerial
installation. You should be aware that the metallic armoring or wire reduces the
cable's relative immunity to lightning.
In addition, under some circumstances, high levels of static electrical charge
can build up on outdoor fiber-optic cables, and workers may need to use special pre-
cautions including grounding of the cable to discharge built-up voltages.
