How to Correctly Wire an Ethernet Cable

Although you can buy Ethernet cables of differing lengths, there may come a time when you need one that’s a specific size. Similarly, if you ever come across a cable with a broken end, you’ll need to fix it. Here’s how to wire an Ethernet cable up.

Thankfully, you don’t need to be a qualified electrician to be able to wire up an Ethernet cable, but you will need some tools at hand before you start.

Before we go into the nitty gritty of the wiring, though, we need to take a look at the types of Ethernet cable available.


There are two types of Ethernet cable you’ll come across when you’re cabling: Cat5 and Cat6. These are Category standard cables types, specifically standard 5 and standard 6. They are both used for networking and feature the same wiring inside the cable.

Cat5 is an older standard, but can still transfer speeds to and from switches and routers up to 1Gb/s – although it does have a bit of an issue with holding those speeds over time. Cat6, however, is the newer of the two, and fully supports 1Gb/s speeds over the network, and has the potential for up to 10Gb/s, although that would be pushing the cable’s abilities to the maximum.

The main difference between Cat5 and Cat6 is the reduced Crosstalk. Electromagnetic signals that come from Ethernet cables can cause what’s known as Crosstalk, when multiple cables are close to one another within a network. The interference caused by cables being too close to each other can slow speeds and also slow the overall quality of the connection due to becoming more error prone. Increased errors can result from Crosstalk, as well as lost packets. Through the incorporation of a new twisted cable design, and by improved the shielding of the cable, the likelihood of Crosstalk between Ca6 cables is greatly reduced, and therefore a better option.


To begin with you’ll need to make sure you have enough Ethernet cable (Cat6 preferably, see above), a set of RJ45 cable ends (or plugs, connectors), plastic cable boots, an RJ45 Crimping Tool, and if possible, a cable tester.

Begin by laying out one end of your Ethernet cable, and, if you have one, place the rubber boot over the cable. The rubber boot isn’t important, it’ll protect the cable end clip from being snagged and broken. Strip off about two inches  of the Ethernet cable plastic sheath. Inside the Ethernet cable you’ll see four pairs of wires, twisted into pairs – which is why Ethernet cable is also called Twisted-Pair.

wiring an ethernet cable

Also, under the cable sheath, you’ll notice a thin piece of plastic called the Rip Cord (or Dental Floss, depending on where you are). If you pull this it’ll cut through a section of the sheath, allowing you to fold it over and around itself. This will help you cleanly cut away the plastic sheath without damaging the wires underneath. You won’t need to use the Rip Cord to slice away much, around half an inch. When you’ve folded back the plastic sheath, cut it off (called Fluting), and cut the Rip Cord.

The four pairs of wires are broken up into colours: A blue pair, orange pair, green pair and brown pair. Individually they’re called white blue/blue, white orange/orange, white green/green, and white brown/brown.

There are two standards of Ethernet wiring: T568A and T568B. Most companies and engineers will use the T568B standard (As we understand the US Government requires type A when used for wiring done under federal contracts, however). In short, as long as both ends match, and any wall sockets you plug them into match, then it really doesn’t matter.

For T568B standard, untwist the wires into the following order:

  1. White/orange
  2. Orange
  3. White/green
  4. Blue
  5. White/blue
  6. Green
  7. White/brown
  8. Brown

Grab one of the cable ends and identify Pin 1. To do so, hold the cable end with the clip facing away from you. Pin 1 is the first pin on the left.

Snip the cable until there’s about 1.5-inches free from the edge of the plastic Ethernet sheath. Hold the wires, and arrange them in the order shown above. Firmly insert the wires into the cable end until the copper wire at the centre of each wire is touching the back of the cable end, and ensuring that the following colours match the pins:

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

Once the wires are in place, grab the crimp tool, and place the cable end in the appropriate slot in the tool. Squeeze the crimp tool all the way down until the ratchet is released (if it has a ratchet function).

Run the rest of the Ethernet cable out to the desired length, giving yourself a few extra inches in case you mess up one the ends, and repeat the process to crimp another end on to the cable.

Grab the cable tester, and check your ends. If all’s gone to plan you should have a length of Ethernet cable that’s good for networking with.

The Extra Mile

You can of course go the extra mile with your cabling. But you will need to plan this out carefully.

With your wired network plan, ensure that you’ve measured the distances to and from the equipment on the network to the router. If you want you can opt for trunking that will fit to the walls and ensure the cables are neatly hidden, along with having network and power points mounted.

You’ll also need to ensure that you can drill through the floor/ceiling to run the cables to the upper or lower floors of your home.

In some cases, it’s best to opt for good cabling on each floor, with a very good powerline adapter between the floors to extend the network.

David Hayward

David has spent most of his life tinkering with technology, from the ZX Spectrum, getting his hands on a Fujitsu VPP5000/100 supercomputer, and coding on an overheating Raspberry Pi. He's written for the likes of Micro Mart, Den of Geek, and countless retro sites and publications, covering reviews, creating code and bench testing the latest tech. He also has a huge collection of cables.

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