Helpful video reference. Wire Wizards, a UK telephone, CCTV and data engineering company, put together this practical guide: "(UK) How to connect a Data Cable to a Cat5 Socket and Cat5 Plug". The technique applies equally to Cat5e and Cat6 cable, which use the same 110-block termination method and the same T568B colour order.
1. Check the cable spec
Look at the print on the outer sheath of the cable. You want Cat5e or Cat6. Plain Cat5 (without the 'e') will still work for basic browsing but is limited to 100 Mbps on runs over about 40 metres. Cat5e and Cat6 both support Gigabit Ethernet at the full 100-metre maximum length.
If the cable is very old and the sheath says only "Cat5" or has no marking at all, it is worth checking whether a faster category cable has already been installed elsewhere in the house before going further.
2. Strip the outer sheath
A cable stripper with an adjustable blade is the safest tool. Set the blade depth to just score through the outer jacket, then rotate the stripper around the cable once and peel back about 40 mm of sheath. If you are using a knife, score lightly and peel -- any nick to the pair insulation underneath will affect performance.
Cat6 cable often contains a plastic cross-shaped spine to keep the pairs separated. You can cut this away once the sheath is off.
3. Keep the twist as long as possible
The tight twist in each pair is what gives Cat5e and Cat6 their noise rejection. Untwist each pair only as much as needed to seat the conductors in the socket slots. For Cat5e, the standard allows up to 13 mm of untwisted conductor at the termination. For Cat6, keep it to 6 mm or less to maintain the Gigabit rating.
This is the step most people get wrong. Untwisting 50 mm looks tidy; it reduces performance.
4. Seat the conductors in T568B order
Most UK home and office data sockets use the T568B standard. The eight positions from left to right are:
- 1: White/Orange
- 2: Orange
- 3: White/Green
- 4: Blue
- 5: White/Blue
- 6: Green
- 7: White/Brown
- 8: Brown
The socket faceplate will usually have a colour-coded diagram printed on the back. Follow the T568B column, not T568A. Mixing the two standards across sockets in the same installation will cause a wiring fault on pins 1, 2, 3 and 6.
5. Punch down and trim
A 110-block punch-down tool is a spring-loaded handle with a slotted tip. Place the conductor in the slot, push down firmly until the tool clicks, and the conductor is seated and the waste end trimmed in one action. Most tools have two sides: one cuts, one does not. Make sure the cutting side is facing the waste end you want to remove.
Work your way across all eight positions. If you do not have a punch-down tool, some keystone sockets can be terminated with a small flat-blade screwdriver, though a proper tool gives a more consistent result.
6. Fit the faceplate
Clip the terminated keystone module into the faceplate cutout until it snaps home. Screw the faceplate to the back box with the two faceplate screws. For a flush finish, tighten evenly so the plate sits flat against the wall.
Repeat the same process at the other end of the cable run, whether that is a patch panel in a cupboard or a second data socket.
7. Test every pair
Plug one end of a basic network cable tester into the socket you have just fitted and the remote unit into the other end. The tester sends a signal down each of the eight conductors in sequence. All eight LEDs should light in order: 1, 2, 3, 4, 5, 6, 7, 8. Any LED that fails to light or lights out of sequence points to an incorrectly terminated or damaged conductor.
A fault on pairs 1 and 2 together, or 3 and 6 together, usually means a crossed pair at one end. Undo the socket, reseat in T568B order and test again.
When to call us
Terminating the socket itself is DIY territory. Running new cable through walls, floors or ceiling voids is where the Building Regulations can apply if the cable sits alongside mains wiring -- that is the point to call Richard, who covers jobs like this across Sandwich.
Need data sockets or network points fitted in Sandwich?
Richard fits Cat5e and Cat6 data sockets, TV points and telephone extensions around Sandwich and east Kent.
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