T568B Wiring Guide: RJ45 Ethernet Cable Pinout & Diagram

T568B wiring is one of the two recognized standards for wiring RJ45 Ethernet cables, the other being T568A. T568B is the most widely used wiring scheme for network cables, especially in residential, commercial, and telecom installations.

T568B Wiring

In this guide, you’ll learn what T568B wiring is, how to wire an Ethernet cable using the T568B standard, and when to choose it over T568A.

📌 What Is T568B Wiring?

T568B is a pinout standard for 8P8C modular connectors (commonly known as RJ45 plugs) used in Cat5e, Cat6, and Cat6a Ethernet cables. The T568B standard defines the order of the color-coded twisted pairs inside the cable for consistent signal transmission.

✅ T568B is defined by TIA/EIA-568 standards and is commonly used in network patch cables, data centers, and structured cabling systems.

📊 T568B RJ45 Pinout Chart

Below is the correct color code for T568B wiring:

🔧 How to Wire T568B Ethernet Cable

Follow these steps to terminate an RJ45 Ethernet cable using the T568B standard:

1. Strip about 1 inch (2.5 cm) of the outer jacket.

2. Untwist and arrange the wires in the T568B order.

3. Trim the ends flat and insert them into the RJ45 plug.

4. Crimp using a RJ45 crimping tool.

5. Use a cable tester to confirm proper continuity.

🔍 T568B Wiring Diagram (Visual Reference)

🧱 T568A vs T568B – What’s the Difference?

Both T568A and T568B serve the same function, but differ in the wire pair assignments. Here’s a quick comparison:

T568B is generally recommended for new installations unless you're matching an existing T568A system.

🔄 Straight-Through vs Crossover (T568B Use Case)

• Straight-through cables: Use T568B on both ends, standard for connecting different devices (e.g., PC to switch).

• Crossover cables: Use T568A on one end and T568B on the other, used for same-device connections (e.g., PC to PC).

🧰 Applications of T568B Ethernet Wiring

T568B is used in:

• Patch cords and Ethernet cables (Cat5e, Cat6, Cat6a)

• Wall jack terminations and patch panels

• Structured cabling systems

• Home and office LAN setups

• PoE (Power over Ethernet) applications

📦 Buy RJ45 Cables or Bulk Ethernet Wire?

At TOT Wire & Cable, we offer:

• Pre-terminated Cat5e/Cat6 RJ45 patch cables

• Bulk UTP/FTP Ethernet cable rolls (305m, 500m)

• Custom-made T568B terminated cables

• Professional support for network cabling projects

👉 Request a Quote  for technical assistance or bulk pricing.