Network cables

Standard Cat5 cable

A standard category 5 patch cable.

There are three common standards for network cable: Cat5 (category 5), Cat5e, and Cat6. Fortunately, they're so similar in design and function that they can be used interchangeably. Cat5 was the original standard; Cat5e and Cat6 are newer versions with better construction. Out of the three, I recommend Cat5e for its excellent cost/quality ratio.

Cat5e is most commonly sold in the form of patch cables, which have plugs pre-attached and can be used to easily “patch” together a connection between two devices. They are available in a variety of colors and lengths.

Crossover cables are a common variation of patch cables; they have an internal wiring scheme that is reversed at one end. Such cables are necessary for linking multiple hubs, connecting a cable/DSL modem to a hub, or connecting two computers directly to each other. Note, however, that you can accomplish the same thing by connecting a regular cable to an uplink port. (If you’re confused, this probably doesn’t apply to you.)

Making your own

RJ45 connectors for Cat5 cable

Aside from the cable itself, you’ll need a bag of RJ45 plugs. They look like RJ11 plugs (the kind used for phone lines), but they have more pins and are noticeably larger. You’ll also need a crimp tool, which is used to attach RJ45 plugs to the ends of the cable.

RJ45 crimp tool

RJ45 crimp tool.

GreatCables is a good place for bulk cable and RJ45 100-packs. Head over to for the crimp tool and smaller RJ45 10-packs.

Once you have the cable, you can start running it where it needs to go. This probably isn’t as easy as it sounds. Some new homes have steel beams that make it hard to wire across floors, and old homes have often been rennovated so much that the contents of the walls are unpredictable. Be ready to drill holes, be ready to patch holes, and plan your wiring so that you can use gravity to your advantage…

…or forget aesthetics, run the cable through the hallway, and hope that you don’t trip over it too often.

Either way, the next step is attaching RJ45 plugs. Start by using your crimp tool to strip about 1/2" of insulation from the outside of the cable. It’s a good idea to score the insulation just enough for you to pull it off with your fingers. DO NOT cut the insulation of any of the 8 wires inside; if you do, cut off the end of the cable and start over.

Once that’s done, arrange the wires in the order diagrammed below. For regular cables, use the 568A arrangement on both ends. For crossover cables, one end should be 568A and the other end should be 568B.

Regular (568A): G/W G O/W Bl Bl/W O Br/W Br *** Crossover (568B): O/W O G/W Bl Bl/W G Br/W Br

Pinouts for network cables. Note that this is a view from the top of the RJ45 plug.

You can untwist the wires to arrange them, but DO NOT untwist more than 1/2"; doing so will cause interference and the cable may fail.

If the wires don’t line up, use the crimp tool or scissors to trim them until they are flush with each other. Then, being careful to maintain their arrangement, insert the wires into an RJ45 plug. They should all slide into separate plastic grooves, and part of the cable’s insulation should end up inside the plug. Check the bottom (clip-side) of the plug to make sure that all of the wires are fully underneath the metal contacts.

When the wires are inserted correctly, It’s time to crimp the plug. Spread the handles of your crimp tool and gently push the plug into the crimp tool’s port. Make sure you push it as far as possible. Then, slowly but forcefully, squeeze the handle. The metal contacts will pierce the insulation of the wires, and a plastic wedge will anchor the cable. Remove it from the crimp tool and give the plug a little tug to make sure it’s properly attached.

Repeat as necessary. Machine wash warm, tumble dry low.