Ethernet Wiring Standards

Jun 6, 2025

Overview

This lecture covers Ethernet wiring standards, focusing on T568A and T568B color schemes, their importance, differences, and practical tips for installation and troubleshooting.

Ethernet Wiring Standards

  • Ethernet wiring follows international and national standards for consistency across countries and buildings.
  • The ISOC181 document defines global networking classes; the ANSI/TIA 568 standard is used in the US for commercial buildings.
  • T568A and T568B are two color-coded wiring schemes defined in these standards for Ethernet cables.

T568A vs. T568B Color Schemes

  • Both T568A and T568B use the same RJ45 connector but arrange wire colors differently.
  • Most US installations use T568B, and organizations typically stick to one standard for consistency.
  • Never mix T568A on one cable end with T568B on the other, especially on a gigabit network.
  • Pins 4, 5 (blue, white/blue) and 7, 8 (brown, white/brown) are the same for both schemes.
  • Main differences are in pins 1, 2 (white/green, green vs. white/orange, orange) and pins 3, 6 (white/orange, orange vs. white/green, green).

Practical Tips for Installation

  • Identify the color scheme used by examining the wire order in the connector.
  • Insert wires into the RJ45 connector, verify the order, and adjust as necessary before crimping.
  • Many jacks and keystone connectors display both T568A and T568B color codes to assist with wiring.

Key Terms & Definitions

  • Ethernet — A network technology for wired local area networking.
  • RJ45 — The standard connector used for Ethernet cabling.
  • T568A/T568B — Color-coded wiring schemes for Ethernet cables.
  • Crimping — Securing wires into a connector.
  • Keystone jack — Modular jack for network cabling.

Action Items / Next Steps

  • Practice identifying T568A and T568B wiring on Ethernet cables.
  • Review the pinout/color order for both schemes.
  • Prepare to crimp or punch down cables using the correct standard.