Ethernet cable yourself: what to buy, how to run it and crimp it

Published 2026-11-03 · 9 min read · By the Alian Digital team

A cable gives the most stable internet, and running one at home is within reach of anyone who can use a drill and a screwdriver. The key is buying the right cable and not rushing the crimp.

Which cable to buy

• Category: Cat5e is enough for gigabit; Cat6 leaves room for the future and handles crosstalk between pairs better. For a house or a new renovation take Cat6.
• Material: copper only (Cu, solid copper on the package). Cheap “CCA” (copper-clad aluminium) breaks, heats up and does not hold the speeds. If the price looks suspiciously low, that is almost certainly what it is.
• Conductor type: for fixed runs in walls and channels use solid (single-strand) cable, which is more reliable in sockets. Flexible stranded (patch) cable is for short links only.
• Shielding: in a flat unshielded (U/UTP) is usually enough. Near heavy electrics or outdoors use shielded (F/UTP) with grounding.
• Outdoors: a dedicated outdoor cable with UV protection. Indoor cable in the sun cracks in a few seasons.

Plan the routes

• Mark where you need sockets: desks, TV, Wi-Fi access points (ceiling or high on the wall), cameras, the network cabinet.
• Bring all cables to one point: convenient for the switch and router.
• One cable run from switch to device may be up to 90 metres, and up to 100 with short patch cords at each end.
• Leave 1 to 2 metres of slack at each end: you will crimp more than once.
• Add “extra” cable where a device might be needed. One extra cable during renovation costs pennies, while chasing a wall later is expensive.

How to run it without trouble

• Keep cable away from heavy 220 V power lines. If you must cross, do it at a right angle and do not run them parallel and touching.
• Do not bend sharply: the bend radius should not be less than 4 cable diameters.
• Do not pull cable ties and clips too tight: hold the cable, do not squeeze it.
• Prefer channels or corrugated pipe: cables can be replaced later.
• Label both ends of every cable: you will thank yourself in a year.

Tools you need

• An RJ45 crimping tool with a cutter.
• A stripper for the jacket (a sharp knife works too, but a stripper is safer for the conductors).
• A cable tester: the most useful thing in the kit, to find mistakes at once. An inexpensive one will do.
• RJ45 connectors for your exact cable (solid and stranded differ, check the package).
• Keystone modules and wall sockets, or a patch panel if you are building a network cabinet.

Crimping RJ45 to the T568B scheme

T568B is the most common scheme. Holding the connector with the contacts up, the wire order from left to right is:

• 1. white-orange
• 2. orange
• 3. white-green
• 4. blue
• 5. white-blue
• 6. green
• 7. white-brown
• 8. brown

• Strip the jacket about 3 cm, taking care not to nick the conductors.
• Untwist the pairs and line up the conductors in the right order. Keep them flat and tight.
• Cut the conductors flat, leaving about 1 cm to the edge of the jacket.
• Push into the connector all the way: the conductors must touch the front wall and the jacket must go under the clamp.
• Crimp in one firm motion and check with a tester.

Use the same scheme at both ends (T568B on both sides). Do not confuse it with a “crossover”, which you do not need now.

Wall socket (keystone) instead of a connector

In the wall the cable ends in a socket, not a connector. The module has colour marking for scheme A or B: choose B, same as for connectors. Lay the conductors by colour, seat them in the contacts and press with the cover or a punch-down tool. No need to trim: the contacts cut through the insulation. Do not untwist the pairs more than 1 to 2 cm before the contact: the shorter the untwisted section, the better the speed.

Testing

• The tester should show 1 to 1, 2 to 2 and so on to 8 without errors.
• Plug in a device and look at the speed in the system: it should say “1 Gbit/s” (1000 Mbit/s). If it says 100 Mbit/s, most likely one pair has no contact: redo the connector.
• If you want to be thorough, run a speed test between two computers on the local network.

Typical mistakes

• CCA instead of copper.
• Pairs untwisted too far (10 cm or more).
• Stranded-cable connectors on solid cable: the contact is unreliable.
• Different schemes at the two ends for no reason.
• Kinks and “spare” cable tied in a knot.
• Cable next to a lift shaft, big electrical panels and lamps with chokes, unshielded.
• Forgetting to label the ends.