minated in either the T568A scheme or the T568B
scheme. The two schemes work equally well and
may be mixed in an installation so long as the same
scheme is used on both ends of each cable.
Each of the four pairs in a Cat 5 cable has dif-
fering precise number of twists per meter to
minimize crosstalk between the pairs. Although
cable assemblies containing 4 pairs are common,
Category 5 is not limited to 4 pairs. Backbone
applications involve using up to 100 pairs. This
use of balanced lines helps preserve a high sig-
nal-to-noise ratio despite interference from both
external sources and crosstalk from other pairs.
The cable is available in both stranded and solid
conductor forms. The stranded form is more
flexible and withstands more bending without
breaking. Permanent wiring (for example, the
wiring inside the wall that connects a wall socket
to a central patch panel) is solid core, while patch
cables (for example, the movable cable that plugs
into the wall socket on one end and a computer
on the other) are stranded.
Maximum cable segment length
According to the ANSI/TIA/EIA standard for
category 5e copper cable (TIA/EIA 568-5-A), the
maximum length for a cable segment is 100 me-
ters (330 ft). If longer runs are required, the use
of active hardware such as a repeater or switch
is necessary. The specifications for 10BASE-T
networking specify a 100 meter length between
active devices. This allows for 90 meters of sol-
id-core permanent wiring, two connectors and
two stranded patch cables of 5 meters, one at
each end.
Category 5 vs. 5e
The category 5e specification improves upon
the category 5 specification by tightening some
crosstalk specifications and introducing new
crosstalk specifications that were not present in
the original category 5 specification. The band-
width of category 5 and 5e is the same - 100 MHz.
P. 10
AUDIOLAB Live Snake 16.8 -
English version
Applications
This type of cable is used in structured cabling
for computer networks such as Ethernet over
twisted pair. The cable standard provides per-
formance of up to 100 MHz and is suitable for
10BASE-T, 100BASE-TX (Fast Ethernet), and
1000BASE-T (Gigabit Ethernet). 10BASE-T and
100BASE-TX Ethernet connections require two
cable pairs. 1000BASE-T Ethernet connections re-
quire four cable pairs. Through the use of power
over Ethernet, up to 25 watts of power can be car-
ried over the cable in addition to Ethernet data.
Cat 5 is also used to carry other signals such as
telephony and video. In some cases, multiple
signals can be carried on a single cable; Cat 5 can
carry two conventional telephone lines as well
as 100BASE-TX in a single cable. The USOC/RJ-61
standard is used in multi-line telephone connec-
tions. Various schemes exist for transporting
both analog and digital video over the cable.
HDBaseT is one such scheme.
Any cable that contains air spaces can breathe
in moisture, especially if the cable runs between
indoor and outdoor spaces. Warm moist air can
cause condensation inside the colder parts of the
cable outdoors. It may be necessary to take pre-
cautions such as sealing the ends of the cables.
Some cables are suitable for "direct burial", but
this usually requires that the cable be gel filled in
order to hinder moisture migration into the cable.
When using a cable for a tower, attention must
be given to vertical cable runs that may chan-
nel water into sensitive indoor equipment. This
can often be solved by adding a drip-loop at the
bottom of the run of cable. Plenum-rated cables
are slower to burn and produce less smoke than
cables using a mantle of materials like PVC. This
also affects legal requirements for a fire sprinkler
system. That is if a plenum-rated cable is used,
sprinkler requirement may be eliminated.
Shielded cables (FTP/STP) are useful for environ-
ments where proximity to RF equipment may
introduce electromagnetic interference, and can
also be used where eavesdropping likelihood
should be minimized.