An RJ45 jack pin numbers chart is the foundational map for any structured cabling installation, defining the exact path for each wire within the connector. Understanding these standardized positions is critical for terminating cables that support Ethernet, VoIP, and other data protocols without signal degradation. This reference eliminates guesswork, ensuring that crimped connections align precisely with the wiring scheme at the other end of the cable.
T568A and T568B Wiring Standards
The two primary wiring standards govern the RJ45 jack pin numbers, dictating the color sequence for each position. T568A is often favored in residential environments and government installations for its noise cancellation properties across multiple pairs. T568B is widely adopted in commercial settings and is frequently the default configuration seen in pre-terminated cables and networking hardware.
Pin Assignments for T568A
Pin Number | Color | Function
1 | White/Green | Transmit Data +
2 | Green | Transmit Data -
3 | White/Orange | Receive Data +
4 | Blue | Line Voltage
5 | White/Blue | Line Voltage
6 | Orange | Receive Data -
7 | White/Brown | Reserved
8 | Brown | Reserved
Pin Assignments for T568B
Pin Number | Color | Function
1 | White/Orange | Transmit Data +
2 | Orange | Transmit Data -
3 | White/Green | Receive Data +
4 | Blue | Line Voltage
5 | White/Blue | Line Voltage
6 | Green | Receive Data -
7 | White/Brown | Reserved
8 | Brown | Reserved
Pin Functions and Data Transmission
RJ48 jack pin numbers 1 and 2 form the first pair, handling transmit signals, while pins 3 and 6 manage receive signals. Pins 4 and 5 carry direct current (DC) power for devices like IP cameras or wireless access points, and pins 7 and 8 are typically reserved for future use or power delivery. This specific arrangement allows for full-duplex communication, where data can be sent and received simultaneously.
Practical Termination and Troubleshooting
When terminating a jack, the clip facing the floor should have pin 1 on the left side, following the standard orientation. A punch-down tool must seat each wire firmly to the correct pin number without damaging the conductor. If a connection fails, verifying the pin numbers with a cable tester is the first step to identify miswires, opens, or shorts that compromise network performance.
