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Ethernet cable wiring guide

Editorial Team Editorial Team Dec 18, 2019

Table of contents:

  1. General information about Ethernet cable
  2. What are the types of Ethernet cables?
  3. Ethernet cable wiring
  4. Ethernet cable connector types
  5. Ethernet RJ45 connection wiring and cable pinout
  6. How to wire Ethernet Cables [Step-by-step guide plus Video instruction]

General information about Ethernet cable

Connecting a computer to a network such as the Internet can be accomplished either with a WiFi or a wired connection. Long before WiFi was available Ethernet cables were the only option to attach a machine to a network. Ethernet cables are primarily connected to a computer at one end and a network switch or router on the other end. Crossover cables are specialized Ethernet cables that are used to directly connect two computers to each other.

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Without Ethernet cables, the World Wide Web and the Internet as we know it could not exist. Those inventions, which have become indispensable in the modern age, would have been impossible without the network connectivity made possible by Ethernet cables.

There are two main categories of Ethernet cables - braided stranded cables and solid cables. The solid cables are more useful for use in fixed locations with the stranded cables better at flexible desktop use.

Ethernet cable

What are the types of Ethernet cables?

There are 5 different types of Ethernet cables available on the market today. They are Cat5, Cat5e, Cat6, Cat6a, and Cat7. The most commonly used cables are of type Cat5 and Cat5e.

Let’s take a closer look at what distinguishes the different kinds of Ethernet cables.

Cat5 - Standing for Category 5, the Cat5 follows its predecessors Cat3 and Cat4 cables. It is the most used type of cable and until the arrival of Cat5e was considered the most efficient and reliable option available. It is made of unshielded twisted pairs (UTP) of wires and has maximum data transmission speeds of 10/100 Mbps.

Cat5e - This is an enhanced version of the Cat5 cable that offers better speed and protection from electrical interference. It is also a UTP cable and can reach transmission speeds of 1000 Mbps.

Cat6 - Category 6 cables increase the transmission performance of the Cat5e variety. Both kinds can handle Gigabit speeds, but Cat6 is better suited to environments where more electromagnetic interference may be present. Cat6 cable is available in both UTP and STP (shielded twisted pairs) form and is more expensive than Cat5e. Its top speed is 1000Mbps.

Cat6a - Augmented Category 6 cable increases transmission speed to 10,000 Mbps and doubles the maximum bandwidth to 500 MHz.

Cat7 - Category 7, also known as Class F cables are comprised of screened, shielded twisted pairs (SSTP) of wires. They are more heavily insulated and are thicker and bulkier that Cat6e cables. They are hard to bend but achieve data transfer speeds of 10,000 Mbps over bandwidths of 600 MHz.

Different Ethernet Categories

Category 5 Category 5e Category 6 Category 6a Category 7
Max. Data
Transmission Speed
10/ 100/ 1000 Mbps 10/ 100/ 1000 Mbps 10/ 100/ 1000 Mbps 10,000 Mbps 10,000 Mbps
Max. Bandwidth 100 MHz 100 MHz 250 MHz 500 MHz 600 MHz

Ethernet cable wiring

There are four twisted pairs of wires inside every Ethernet cable. An ethernet cable wiring diagram will show that only two of these pairs are actively used in the transmission of data. The Orange and Green pairs of wires are used in both the T568A and T568B standards, but for different purposes.

In the T568A standard, the Orange and White/Orange pair of wires is used to receive data with the Green and White/Green pairs used to transmit. In addition to having the wires in a different pinout configuration, the T568B style cable reverses the transmission and receiving pairs. It transmits through the Orange wires and receives data through the Green pair.

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Ethernet cables are wired in a specific way and the internal wires conform to an Ethernet cable color code. There are 8 wires inside an Ethernet cable. They are twisted into four pairs of wires that follow the color code for Ethernet cables. A pair will consist of a solidly colored cable and a white cable with a stripe of the solid color. In some cases, there is no stripe so the only way to tell which white wire you are handling is to determine the color of the solid wire in the pair.

There are two distinct color codes for Ethernet cables. The T568B scheme is the standard for most Ethernet use in the United States, especially for business purposes. T568A is the standard followed by most European and Pacific nations as well as the United States government. The cables are functionally equivalent, so as long as you are consistent it really doesn’t matter which you use.

Here are the standard ethernet cable wiring colors and associated RJ45 pinout numbers for the two color schemes for straight-through Ethernet cables. We will discuss the meaning of the Ethernet cable colors below when we look at the functionality of the twisted pairs.

Ethernet cable colors

Ethernet crossover cable wiring is different since it will connect two computers rather than a computer to a network. Here is an example of how a T568B crossover cable is internally wired.

A crossover Ethernet cable has different wiring at the two ends of the cable. This is why they are called crossover cables. Here are the wire colors and pinouts for the 2 ends of a crossover cable.

Crossover Ethernet cable

Ethernet cable connector types

Ethernet cables are useless without connectors to attach them to switches, routers or network hubs. The RJ45 plug is an eight position, eight contact (8P8C) connector. It has 8 locations spaced around 1mm apart. The Ethernet cable wires are inserted into the connector by using a special cable crimping tool. Ethernet cables and the RJ45 connectors need to be crimped into the proper wiring pattern in order to function correctly.

You need to choose the right type of RJ45 connector for the type of cable that you are planning on using. Cat7 cables and Cat6e employ shielded twists pairs of wire and need RJ45 connectors designed specifically for them. Using an incorrect connector will render your cables useless.

Ethernet cable

Ethernet RJ45 connection wiring and
cable pinout

The RJ in RJ45 stands for registered jack and is the electrical connection standard that defines how wires are arranged at the end of an Ethernet cable. There are two standards for ordering the colors of the Ethernet cable’s wires with the 8 pinouts on the RJ45. As previously noted, the pinouts for the T568A and T568B straight-through Ethernet cables are:


Pin 1. White/Green
Pin 2. Green
Pin 3. White/Orange
Pin 4. Blue
Pin 5. White/Blue
Pin 6. Orange
Pin 7. White/Brown
Pin 8. Brown


Pin 1. White/Orange
Pin 2. Orange
Pin 3. White/Green
Pin 4. Blue
Pin 5. White/Blue
Pin 6. Green
Pin 7. White/Brown
Pin 8. Brown

How to wire Ethernet Cables

Ethernet cables can be expensive and when using a lot of cable it may be worthwhile to wire your own. Wiring ethernet cable by purchasing bulk Ethernet cable and Ethernet cable connectors lets you construct the exact length of cable that you need. Here’s how you would go about wiring an Ethernet patch cable.

  1. Strip off approximately 2 inches of the cable sheath.

  2. Untwist the pairs of wires.

  3. Align the colored wires using one of the schemes listed in the above discussion of Ethernet wiring.

  4. Evenly trim the wires leaving about 1/2 to 3/4 inch exposed from the sheath.

  5. Making sure the wires are in the correct order, insert the wires into an RJ45 plug. The cable’s sheath should be about 1/2 inch into the plug.

  6. Use a crimper tool and crimp the RJ45 plug.

  7. Verify that all of your wires are still in the right order and that they make good contact with the metal contacts inside the RJ45 plug.

At this point, you can cut the cable to the length you need and repeat the above steps on the other end of the cable. Wiring Ethernet cables in this manner gives you total control over the length of the cables used in your installation.

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