Quick answer: An ethernet outlet is a female RJ45 keystone jack mounted in a wall plate, with solid cable punched into the back and a patch cord plugged into the front. The jack’s category sets the ceiling for the whole link: a Cat6 jack in a Cat6a run limits the channel to 250 MHz. Specify jack and cable at the same category, wire both ends to the same pattern, T568A or T568B, and keep the untwisted length under 13 mm. A single outlet costs very little; the labour to redo it does not.
Outlets are the part of a network that people touch and the part most likely to be installed badly. A run that tests fine at the panel can fail at the outlet because the pairs were combed straight before punching, and the symptom is a link that works at gigabit on a cool day and drops to 100 Mbit/s under load.
What the outlet consists of
Keystone jack and plate
The jack clips into a 14.5 by 16 mm opening. Plates hold one to six of them, and modular plates let you mix RJ45, coax and fibre in the same frame. Behind the plate, the solid cable is punched into insulation displacement contacts; in front, a stranded patch cord plugs in. The jack is the mechanical interface and also the place where crosstalk compensation is built in.
Flush, surface and floor boxes
A flush box needs a 35 mm deep back box in the wall and gives the neatest result. A surface box screws to the wall and is the practical choice for brick or concrete. A floor box costs more and needs a trapdoor, but it is the only option for a conference table. Whatever the type, leave 200 to 300 mm of slack cable behind the plate for future re-termination.
Wiring and testing
One pattern for the whole site
T568B is the common commercial choice: white-orange, orange, white-green, blue, white-blue, green, white-brown, brown on pins 1 to 8. T568A swaps the green and orange pairs. Both work; mixing them at opposite ends of one cable does not, because the pairs no longer match and the link either fails or runs at 100 Mbit/s.
Punch, then certify
Punch each conductor with a proper tool, trim the excess in the same motion, and check that the jacket is held by the strain relief rather than sitting outside it. Then test the permanent link with a certifier, not a continuity tester. A continuity tester passes a link with a split pair, which is exactly the fault that ruins gigabit performance.
What to specify
| Item | Match to | Why |
|---|
| Jack category | Cable category | The lower of the two sets the link ceiling |
| Shielded jack | Shielded cable and bonded plate | Floating shields make crosstalk worse |
| Back box depth | 35 mm minimum | Bend radius for Cat6a |
| Patch cord | Same category, stranded | Stranded cable must not go in the wall |
Mistakes that show up months later
Using telephone cable is the classic: it has the right connector and four pairs, but no twist rate specified for data, and it works at 100 Mbit/s for a while. Daisy chaining two outlets on one cable is the second: ethernet is point to point, so a second outlet must have its own run to the switch. The third is a plate with four jacks in a row, where alien crosstalk between neighbours limits 10GBASE-T even when each link passes on its own.
For a clean result, terminate at a patch panel rather than at loose plugs, use short patch cords at both ends, and label both ends with the same identifier. The Ethernet wall plates guide covers plate formats, the RJ45 connector reference covers plugs, and the Ethernet patch leads page covers the cords that complete the channel.
Surface-mount and trunking
Where the wall cannot be chased, a surface box with mini trunking is the honest solution. It costs less than making good plaster, it can be added to later, and it keeps the cable accessible if a jack fails. Run the trunking vertically from the skirting or the ceiling void, use a 20 mm profile for two cables, and avoid long horizontal runs at skirting height where furniture and vacuum cleaners will hit them. The plate then sits proud of the wall, which looks deliberate rather than improvised if the trunking is straight.
Practical scenarios
- Home office with one wall outlet: Cat6 jack and Cat6 cable, T568B at both ends, tested with a cheap certifier before the furniture goes back.
- Office fit-out with 40 outlets: number every outlet on the plate and at the panel, and certify 100 percent rather than a sample, because a single split pair will be blamed on the network for months.
- Retrofit in a brick wall: surface box with a short conduit to the ceiling void, rather than chasing the wall for a flush box.
- Conference table: floor box with two RJ45 jacks and one HDMI pass-through, so laptops do not need a cable across the table.
FAQ
Can I use a phone jack as an ethernet outlet?
No. An RJ11 jack has four or six contacts and the cable behind it is not rated for data. Some installations reuse telephone cable and it links at 100 Mbit/s, but the twist rate and crosstalk are unspecified, so gigabit is unreliable and no certification is possible.
Does the outlet need to match the switch speed?
The outlet sets the channel’s bandwidth; the switch sets the negotiated speed. A Cat5e outlet on a 2.5G switch will often negotiate 2.5G, and a Cat6a outlet on a gigabit switch runs at gigabit. Match the outlet to the cable and let the electronics negotiate.
How many outlets should a room have?
Two per desk position is the practical minimum, because one may be needed for a phone or a printer, and adding a switch later costs more than a second cable. A living room benefits from outlets behind the television and at the router position.
