RJ45 Wiring Diagram T568B Standard

Wiring scheme B (or T568B) is used for RJ45 wiring and uses different wiring colours to scheme A (or T568A). If you compare the pin functions of both scheme A (T568A) and scheme B (T568B) you will find that they are the same, and only the wiring colours are different. According to the ANSI/TIA-568-C.2 standard, scheme B is optional; however, it is the most popular because it matches the earlier AT&T 258A scheme. Being an old timer, I prefer to use this on new installations.

A or B?

Providing you use the same scheme at both ends of your patch cable, then either scheme will work. However, you should always standardise on using one scheme throughout the network.

In many cases, the facility you work at will already have an established scheme; hence, one simply follows the standard already in place.

Wiring Diagram Colour Code

Pin Connections	Colour	Ethernet function
1		TX+
2		TX-
3		RX+
4		NOT USED
5		NOT USED
6		RX-
7		NOT USED
8		NOT USED

Here is the wiring diagram for scheme B (or T568B) showing the pinout connections, and wire colour code.

RJ45 Wiring Order / Colours

The RJ45 jack plug diagram shown above uses the (colours) wiring order for scheme B (EIA/TIA-568B).

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