RJ45 Pinout: RJ45 Ethernet Color Wiring Guides – RJ45 Wiring Instructions

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3 How To Make RJ45 Network Patch Cables – Cat 5E and Cat 6

RJ45 TIA568A Pinout

The TIA568A (Telecommunications Industry Association) standard is the preferred method of terminating cable. The solid color wires and the striped wires are always alternated with pin 1 always being stripped. Pair 1, blue/blue-white is always on pins 4 & 5, in the middle.

The TIA568B, also known as 258A, a similar standard by AT&T which works just as well as the 568A. The TIA committee chose to include AT&T’s 258A standard, which they call 568B. TIA cabling standard states you may use either 568A or 568B. The thing that is important is to be consistent in cabling your system, in other words, do not mix these two configurations.

RJ45 TIA568B Pinout (AKA 258A)

RJ45 TIA568B Pinout

Why are the wires moved around? Actually, they are laid out logically. Ethernet was originally designed to run over the same cabling system as telephone systems, created by AT&T as StarLAN. If you plug a 4 wire telephone RJ-11 into the 568B, pins 2 and 3, the middle pins of the RJ11 would connect to the middle of the RJ45, pins 4 and 5 which is what is required for the 1 line telephone. If you plug an Ethernet cable into it, pins 1 and 2 will be used as one pair, and pins 3 and 6 will be used as another and there will be no conflicts.

Which to use? If the job specification calls out a specific wiring pattern, use it. Do you or the customer have a preference? Are you adding to an existing setup? If so, determine what the current wiring is and make it the same.