Information Technology Reference
In-Depth Information
There is also a type of flat cable that consists of paired wires positioned side to
side. This cable, which is used for undercarpet applications, has similar characteris-
tics to other paired cables covered earlier in this chapter.
Nonpaired Wire Sizes
There are many wire sizes associated with nonpaired wire. Theoretically, any con-
ductor size may be used, but you will probably find that sizes between 18 and 26
gauge (AWG) are the most common for this type of wire. Telephone 4-wire and sil-
ver satin are generally 22 and 26 gauge, respectively. Ribbon cable can really be any
wire gauge, although the usual range is 26 to 30 gauge.
Nonpaired Electrical Characteristics
Nonpaired wire is generally characterized in terms of resistance per linear foot. For
example, 24 gauge annealed copper wire has a resistance of 25.7 ohms per 1000 ft.
Complete specifications for copper wire are available in several reference hand-
books. This is very useful information if you are using the wire to supply power or
signaling voltages, such as door bells or fire alarms.
Nonpaired wire is really not intended for transmission at any frequencies
above voice, and even there, the transmission characteristics are poor to the extent
they are consistent. Of course capacitance may be specified for ribbon cable, since
it is used to interconnect electronic circuits.
Nonpaired Insulation
The insulation types for nonpaired wire are identical to those for twisted-pair wire.
The same insulation types are used and care must be taken in plenum or riser spaces,
in accordance with the NEC and local standards.
Nonpaired Color Coding and Marking
A very wide variety of wire insulation and jacket colors are available for nonpaired
wire. However, for our purposes in telecommunications, there are some common
color coding standards that are useful.
The round 4-wire nonpaired cable that is used in some residential wiring used
the colors green, red, yellow, and black. This cable was originally designed for sin-
gle-circuit use—that is, one phone line. The green and red wires supplied the voice
signal (tip and ring), and at one time (a long, time ago), the yellow supplied ringing
