T568A and T568B are the wiring standards that definethe pinout (connection order) for terminating twisted-pair network cable in
eight-pin modular connector plugs and jacks. These wiring standards are one
part of the TIA/EIA-568 telecommunications cabling standards. The American
National Standards Institute (ANSI), Telecommunications Industry Association
(TIA), and Electronics Industries Alliance (EIA) are in agreement on the use
of T568A and B. Both standards specify the wiring schemes for the connection
of twisted-pair copper cable into eight-position RJ45 connectors and jacks
for data transmission. The twisted pair cable is comprised of four wire
pairs that provide eight conductors. The pairs feature blue, orange, green
and brown colours. Each pair has a solid colour wire and another wire that
is striped with white and the same colour. Once the pairs are untwisted,
eight separate wires are available to match the eight pins on a jack or

The T568B Wiring Standard

In commercial environments, the T568B wiring standard
is more commonly used for telecommunication
. However, the 568A assignments are frequently seen in
residential applications. Cabling expansions are made according to a
network's current wiring scheme in order for wires to match up and data
signals to transmit. Both T568A and T568B wiring standards are
straight-through schemes.

Difference in T568B and T568A Wiring Schemes

The pair-to-pin assignments are different in the T568B and
T568A wiring schemes. This difference is easily seen with
pin positioning. The green and orange pairs (2 and 3) are switched. Patch
cords can be purchased that are pre-wired for T568B or 568A connectivity.
Comms Express can provide additional information on these factory wired
patch cables.

Related Links

RJ45 Connectors & Adapters
Network Installation & Essentials

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