Page 85 - Optical Communications Essentials

Optical Fiber Cables

Optical Fiber Cables 75

TABLE 5.2. Cable Markings Based on the U.S. National Electric Code and UL Test
Specifications
Marking Cable name UL test Substitute
OFNP Optical fiber nonconductive plenum UL 910 None
OFCP Optical fiber conductive plenum UL 910 None
OFNR Optical fiber nonconductive riser UL 1666 OFNP
OFCR Optical fiber conductive riser UL 1666 OFCP
OFN Optical fiber nonconductive UL 1581 OFNP or OFNR
OFC Optical fiber conductive UL 1581 OFCP or OFCR

■ Riser cables. A riser is an opening, shaft, or duct that runs vertically between
one or more floors. Riser cables can be used in these vertical passages. Riser-
rated cables are UL-certified by the UL-1666 riser fire test method as having
adequate fire resistance for installation without conduit in areas such as ele-
vator shafts and wiring closets. As noted in Table 5.2, these cables are termed
OFNR (optical fiber nonconductive riser) or OFCR (optical fiber conductive
riser). Note that plenum cables may be substituted for riser cables, but not
vice versa.
■ General-purpose cables. A general-purpose area refers to all other regions
on the same floor that are not plenum or riser spaces. General-purpose
cables can be installed in horizontal, single-floor connections, for example,
to connect from a wall jack to a computer. However, they cannot be used
in riser or plenum applications without being placed in fireproof conduits.
To qualify as a general-purpose cable, it must pass the UL 1581 vertical-
tray fire test. As shown in Table 5.2, these cables are rated OFN (optical
fiber nonconductive) or OFC (optical fiber conductive). Note that plenum or
riser cables may be substituted for general-purpose cables, but not vice
versa.

5.4. Outdoor Cables
Outdoor cable installations include aerial, duct, direct-burial, underwater, and
tactical military applications. Invariably these cables consist of a loose-tube
structure. Many different designs and sizes of outdoor cables are available
depending on the physical environment in which the cable will be used and the
particular application. Some important designs are described here.

5.4.1. Aerial cable
An aerial cable is intended for mounting outside between buildings or on poles
or towers. The two main designs that are being used are the self-supporting and
the facility-supporting cable structures. The self-supporting cable contains an

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