What’s the difference between T568A and T568B wiring schemes?

T568A and T568B are the standards specified by ANSI, TIA, and EIA for RJ45 jacks and plugs that refer to the position of the wires inside the eight-position modular plugs.

These two standards are very alike. The only visible difference between them is that pairs 2 and 3 (green and orange) are interchanged.


What’s the similarity between T568A and T568B?

T568A and T568B are both wiring schemes for terminating twisted-pair copper network cables into 8-position RJ45 jacks and connectors.

Here’s why

These cables’ pairs consist of four colors (blue, orange, green and brown) and each pair consists of colored wired twisted together with another wire of the same color, striped with white.

When you untwist the four pairs, they result in 8 individual wires one for each connector’s plug.

Nevertheless, though you may think the only difference between T568A and T568B is the swap between the orange and the green cable:

There are a couple of compatibility differences that could affect your decision when choosing an RJ45 scheme for your infrastructure.

You see… T568B is a more up-to-date scheme and is the more widely chosen wiring scheme because it matches AT&T’s 258A color code.

And also, it offers backward compatibility with one-pair USOC wiring schemes..

Now comes the question, can T568A and T568B be mated?

As a universal rule, T568A and T568B cannot be combined because it could degrade signal quality. When building a network infrastructure from the ground, you are free to choose your wiring scheme, but always keep in mind that T568B is the preferred one in the U.S.

But when expanding and existing network, it is crucial to continue using its original wiring standard.

Let's build it up: T568A or T568B?

  • When building a residential network, choose T658A wiring scheme.
  • If the network project configurations are available, choose the specified wiring scheme.
  • Duplicate the wiring scheme that’s already being used when escalating a network.

    Wiring Standards

    Pin #

    T568B

    T568A

    1

    White/Orange

    White/Green

    2

    Orange

    Green

    3

    White/Green

    White/Orange

    4

    Blue

    Blue

    5

    White/Blue

    White/Blue

    6

    Green

    Orange

    7

    White/Brown

    White/Brown

    8

    Brown

    Brown

     
    June 27, 2016 by

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