How to crimp cable terminals
Updated: October 2026
You have stripped a wire, the terminal is in the jaws, and the question is whether to squeeze until it looks flat. A crushed barrel is not a joint. How to crimp cable terminals comes down to three matches: the conductor in the barrel, the die that belongs to that terminal, and a ratchet that is allowed to finish. This page is the sequence for the insulated sleeves, ferrules and tube lugs in the [cable terminals comparison](/hub/electrical-equipment/cable-terminals). Which box to buy sits on the buying guide and the best-listings page. Prices and review notes are from the amazon.co.uk listings captured on 21 October 2026.
You have stripped a wire, the terminal is in the jaws, and the question is whether to squeeze until it looks flat. A crushed barrel is not a joint.
You have stripped a wire, the terminal is in the jaws, and the question is whether to squeeze until it looks flat. A crushed barrel is not a joint. How to crimp cable terminals comes down to three matches: the conductor in the barrel, the die that belongs to that terminal, and a ratchet that is allowed to finish. This page is the sequence for the insulated sleeves, ferrules and tube lugs in the cable terminals comparison. Which box to buy sits on the buying guide and the best-listings page. Prices and review notes are from the amazon.co.uk listings captured on 21 October 2026.
Our top picks
| Badge | Product | Die in the box | Family | Conductor size | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  QLOUNI QLOUNI open-barrel pin kit | Yes, open-barrel crimper, removal tools and tweezers | Open-barrel pin terminal kit | By series, from 0.2–0.75 mm² to 0.5–1.5 mm² | 6.3 | about £29.98 | View offer |
 AivaToba AivaToba bootlace ferrule kit | Yes, 4-jaw square ratchet | Bootlace ferrule kit with ratchet | Bullet 0.25–10 mm²; size field says 0.5–10 mm² | 7.6 | about £17.99 | View offer | |
 AivaToba AivaToba insulated crimp kit | Yes, ratchet crimper | Insulated crimp kit with ratchet | Red 0.5–1.5 mm²; blue 1.5–2.5 mm²; yellow 4.0–6.0 mm² | 7.0 | about £23.99 | View offer |
On this page
Strip, and do not cut the strands
Start with a strip that leaves the strands whole. Nicking the copper with the stripper is the usual way a later tug fails. The bare copper should sit in the barrel, and the insulation should stop at the mouth rather than disappear inside it.
On a tube lug, look through the inspection hole if the lug has one and check that the strands have reached it without a tuft of insulation. If the barrel is visibly larger than the cable, stop. The next choice is the die, not a harder squeeze with the wrong tool.
Three dies, not one pair of pliers
An insulated red, blue or yellow terminal wants the matching colour cavity in a ratchet. AivaToba’s insulated kit is the listing in this set that includes those jaw marks, at about £23.99. Gorffy’s 300-piece tub starts yellow at 2.5 mm², so you follow the sleeve you are holding. One pair of pliers is not that die.
A bootlace ferrule wants a square or four-jaw tool, not that colour ratchet. AivaToba’s ferrule kit includes model HSC8-6-4A. Do not close bootlaces in the red, blue and yellow jaws. Ferrule colour and Regulation 526.9 stay on the bootlace ferrules page. A tube lug wants a lug die sized to the barrel, which none of the lug packs includes. QLOUNI’s open-barrel crimper is a fourth shape, and it is not a lug die.
Finish the ratchet, then look
A proper insulated ratchet does not release until the cycle finishes. If you open it early because the handles feel hard, you have an under-crimp: the barrel may look closed and the wire will still pull. A tug on the bench is not a BS EN IEC 60352-2 test.
After the tool releases, look before you tug. Trapped insulation in the barrel, a cracked sleeve, or a barrel crushed flat are reasons to cut the terminal off and start again. Do not add solder to improve a crimp. The IET’s Wiring Matters mythbuster treats solder under a screw as a joint that can creep.
Ring or fork, once the crimp is sound, is a stud choice rather than a second squeeze. That split is on the ring or fork terminal page.
When you put the tool down
Stop when the cable is part of a fixed installation in a dwelling. Part P of the Building Regulations 2010 is that boundary. In England, notifiable work includes a new circuit and a consumer-unit change. Regulation 16 of the Electricity at Work Regulations 1989 puts fixed wiring with a competent person.
Voltage on the listing still limits what you just crimped. A lug printed at 12 V DC does not become a 230 V mains terminal because the crimp looked neat. Gorffy’s insulated tub is listed at 120 V. Bolatus prints 230 V AC. Blank voltage is not a hidden mains rating.
Common questions
Where do I put the terminal in the tool?
Put an insulated terminal in the jaw marked for its colour, and put a bootlace ferrule in a square or four-jaw die. A tube lug goes in a lug die matched to the barrel. The red cavity is not a home for a ferrule, and pliers are not a substitute. AivaToba’s insulated kit is the colour-jaw ratchet in this set. The four-jaw model HSC8-6-4A is the ferrule tool in the other AivaToba kit.
What happens if I open the ratchet early?
You leave an under-crimp. The handle force is the tool finishing the cycle, not a signal to release. If the terminal slips before the crimp, the AivaToba reviews say the release lets you reset. Opening halfway because the handles are stiff is how a wire pulls out later, even though the sleeve looks closed.
Can I use the red-blue-yellow tool on a bootlace ferrule?
No. The colour cavities are for insulated ring, fork, spade and butt terminals. A ferrule needs the square jaw. The insulated AivaToba kit’s Included Components line says ferrule pliers, and the title is still an insulated-terminal kit. Follow the jaw in your hand, not that parts line.
How do I check a tube lug without a lab?
Use the inspection hole if the lug has one, confirm the strands fill it, and reject trapped insulation, a cracked barrel or a crimp that has gone flat. Then tug. There is no newton figure to quote, and these listings do not show a BS EN IEC 60352-2 or BS 7609 test. A tug that holds on the bench is only that.
Should I solder as well as crimp?
No. Solder is not a repair for a doubtful crimp, and solder under a screw can creep, which is the IET’s point in the Wiring Matters mythbuster. Gorffy’s PVC sleeves are also described as unwilling to slip off for soldering. Heat-shrink, where a pack includes it, is a cover after the crimp, warmed with a heat gun rather than a naked flame.
Which jobs are not a DIY crimp?
Consumer units, new circuits, special locations, meter tails, aluminium conductors, overheated joints, and EV high-voltage connectors. In England those fixed-wiring jobs can be notifiable under Part P. The person who should finish them is a competent person, typically through a registered scheme, not a tighter squeeze on a terminal from this set.
Related pages
Sources
Public UK sources from the research digest, used on 22 October 2026. Shelf prices and star lines are the amazon.co.uk figures for these 12 listings.
- Voltimum UK: Termination of conductors (retrieved 22 October 2026)
- IET Wiring Matters: Mythbuster 5, terminal blocks (retrieved 22 October 2026)
- IET EngX: Ferrule crimps (retrieved 22 October 2026)
- legislation.gov.uk: Building Regulations 2010, Schedule 1, Part P (retrieved 22 October 2026)
- legislation.gov.uk: Building Regulations 2010, regulation 12 (retrieved 22 October 2026)
- HSE: Electrical safety introduction (retrieved 22 October 2026)
- Electricity at Work Regulations 1989, regulation 16 (retrieved 22 October 2026)
- Furneaux Riddall: terminals guide (retrieved 22 October 2026)