Helpful video reference. The video above is Gary Hayers at GSH Electrical's "Terminating PVC/PVC Twin and CPC Cables (How To Strip and Terminate Twin and Earth Cables)". GSH Electrical is a UK electrical training channel with more than 170,000 subscribers, producing student training aids for City and Guilds and EAL Level 2 and 3 qualifications. Gary is a former installation electrician who has spent 19 years teaching at Tresham College. The stripping and termination method shown reflects UK practice and BS 7671 requirements throughout. Watch it alongside this guide. Watch on YouTube.
1. Gather what you need
You need a cable knife or a purpose-made twin-and-earth stripper (the dedicated tool is much faster and less likely to nick the conductor insulation), a pair of wire strippers, a short length of green-and-yellow sleeving, and the accessory you are terminating into. Have a small flat-head screwdriver for terminal screws and, on push-in terminals such as Wago lever connectors, just the stripped conductor is enough.
Check that the cable size matches what the circuit calls for. 1.0 mm² twin and earth for lighting, 1.5 mm² for lighting where runs are long, 2.5 mm² for socket circuits. Using wire strippers set for the wrong gauge will either not grip the insulation at all or nick the conductor.
2. Measure and strip the outer sheath
Hold the cable against the back box to judge how much sheath needs to come off. For a standard 25 mm single-gang back box, about 50–60 mm of sheath removal leaves enough tail to reach all terminals comfortably. For deeper back boxes or ceiling roses, strip a little more — 75 mm is a safe working allowance.
With a cable knife, score around the sheath at the right point. Use light pressure — you are cutting through the outer PVC layer only, not into the insulation beneath. Run the knife along the cable lengthways to split the sheath, then peel it back and pull it free. With a dedicated twin-and-earth stripper, you set the depth, slide it along, and the sheath peels away cleanly in one movement.
Once the sheath is off, tidy any ragged edge. The sheath should end at a clean line and the inner conductors should be undamaged.
3. Strip the conductor insulation
Set the wire strippers to the correct jaw notch for the conductor size. For 1.5 mm² cable use the 1.5 mm² notch, and so on. Strippers with adjustable jaw depth stop you stripping too much or too little at once.
Strip 8–10 mm of insulation from the live (brown) and neutral (blue) conductors. The exposed copper should fill the terminal barrel with no bare copper visible outside the terminal face once the conductor is inserted and the screw tightened. Too short and the terminal may not grip; too long and bare copper sits outside the terminal, which is a fault on any inspection.
Do not twist the copper strands excessively. Two or three turns to consolidate them is fine. Excessive twisting reduces the cross-sectional area and can cause the conductor to break under the terminal screw.
4. Sleeve the earth conductor
The bare copper circuit protective conductor (CPC) in twin and earth cable must be sleeved with green-and-yellow insulation at every termination. This is a BS 7671 requirement, not optional. Without sleeving, an inspector will flag it as an observation at minimum and a C2 code if there is any risk of contact with the bare conductor.
Cut a length of green-and-yellow sleeving long enough to cover the CPC from the end of the outer sheath down to within a couple of millimetres of where it enters the terminal. Push it over the bare copper from the end. It should sit snugly. If it bunches up, ease it along gently rather than forcing it.
Leave just enough bare tip exposed at the end for the terminal to grip. Typically that is 8–10 mm, the same as the other conductors.
5. Make the terminations
Insert each conductor straight into its terminal. On screw terminals, push the conductor in fully, then tighten the screw firmly — not as hard as you can, but enough that a light tug does not pull it free. Overtightening on older plastic accessories can crack the terminal block. The right feel is a solid resistance when the screw stops, not a creak or crunch.
On lever-style connectors (Wago or similar), lift the lever, insert the stripped conductor fully until it bottoms out, then push the lever back down. These are quick to use but require the conductor end to be cut cleanly square — a diagonal tip can miss the contact blade.
Where there are two cables entering the same terminal (common on ring circuits), both conductors go into the same terminal together. Make sure both are fully inserted before tightening.
6. Double-check before closing up
Before fitting the faceplate, check each connection: no bare copper outside any terminal, no insulation caught under a terminal screw, and the earth sleeving covering the CPC right back to the outer sheath. Give each conductor a light tug. None should move.
Fold the conductors neatly back into the back box. Do not force them in — if there is not enough room, ease them into a gentle arc rather than bending them sharply back on themselves. Sharp bends weaken conductors over time.
Refit the faceplate without pinching any conductor under the edge. Tighten the fixing screws evenly. Restore power at the consumer unit and test the circuit.
When to call us
Stripping and terminating a cable correctly is a learnable skill, but it sits inside a wider context of knowing which circuit you are working on, what load it carries, and what the consequences are if a connection fails. If you are at the stage of asking "which terminal does this go in?", that is usually the point to call a local electrician for a check or to do the job properly from the start.
Need wiring work in Sandwich?
Richard works on small local jobs at the £10 per 10-minute rate. New sockets, light fittings, extensions — if it involves terminating cable, it is worth a call.
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