Cabletron Systems 100BASE-FX, Cabling Manual

Page: 93 / 192

Cabling Types 9-7
Token Ring Media
Category 3
UTP cabling that is built to the Category 3 specification consists of two or more
pairs of solid 24 AWG copper strands. Each strand, approximately 0.02 inch thick,
is surrounded by a layer of insulation. The characteristics of the insulation are
determined by the fire resistant construction of the cable (plenum cable is thicker
and made with slightly different material than normal PVC cabling).
The individual wires are twisted into pairs. The twisted pairs of cable are laid
together along with a thin nylon cord. This “ripcord” is useful for stripping the
outer jacket of the cable, which may be low-smoke PVC plastic or a plenum-rated
insulating material. The outer jacket surrounds, but does not adhere to, the wire
pairs which make up the cable.
Category 3 UTP cabling must not produce an attenuation of a 16 MHz signal
greater than 40 dB/305 m (1000 ft) at the control temperature of 20
°
C.
Category 4
Category 4 UTP cabling is constructed in the same manner as the Category 3
cabling discussed previously. Category 4 UTP is constructed using copper center
strands of 24 or 22 AWG. Each strand is insulated and twisted together with
another strand to form a pair. The resulting wire pairs are then covered by a
second layer of insulating jacketing.
Category 4 UTP must not produce an attenuation of a 16 MHz signal greater than
27 dB/305 m (1000 ft) at the control temperature of 20
°
C.
Category 5
Category 5 UTP cabling is manufactured in the same fashion as Category 3 cable,
but the materials used are of higher quality and the wires that make up the pairs
are more tightly wound.
Category 5 UTP consists of 2 or more pairs of 22 or 24 AWG wire. Category 5 cable
is constructed and insulated such that the maximum attenuation of a 16 MHz
signal in a cable run at the control temperature of 20
°
C is 0.655 dB/m
(25 dB/1000 ft). A cable that has a higher maximum attenuation than 0.655 dB/m
does not meet the Category 5 requirements.