RJ45 Pin colour coding according to EIA/TIA 568A and 568B

The RJ45 has become the dominant connector for copper cabling. The term ‘RJ45’ is not standardized, but it’s widely used. The standard series EN 60603-7 (international: IEC 60603-7) specifies the RJ45 in both, shielded and unshielded versions, and from category 5 to category 6A.

The American standard EIA / TIA 568 defines two different colour coding for RJ45 plugs and jacks. The colour coding T568A was originally developed for the military. T568B, which was developed for civil use, has become common for most installations by now.

The colour coding of EIA / TIA are not contradictory to EN 50173. EN 50173 points to EN 50174, which contains both coding schemes. Either one may be used, but both ends of the cable have to be connected in the same manner.