Independent comparisons. We may earn from shop links. More info

How to crimp a cable lug

Updated: October 2026

You have the tool in your hand, a copper lug, and a cable that still has to stay on the stud after the handles close. A closed stroke, or a hammer that has bottomed, can still leave a barrel you can pull off. This is how to crimp a cable lug on a copper conductor you can see and remake: cut square, strip to the barrel, crimp once in the matching die, then tug before you insulate. If the conductor moves, that lug is scrap. The tools these steps refer to are the ones on the [cable lug crimper comparison](/hub/electrical-equipment/cable-lug-crimper). Which mechanism to buy is on the [cable lug crimper buying guide](/hub/electrical-equipment/cable-lug-crimper/sub/cable-lug-crimper-buying-guide), not here.

You have the tool in your hand, a copper lug, and a cable that still has to stay on the stud after the handles close. A closed stroke, or a hammer that has bottomed, can still leave a barrel you can pull off.

Our top picks

Dechengbao Dechengbao HX-50B single crimper

Best overall

Dechengbao Dechengbao HX-50B single crimper
9.4/10about £22.99
View offer
KAIWOLF Kaiwolf HX50B rotary crimper

Best value

KAIWOLF Kaiwolf HX50B rotary crimper
9.2/10about £22.99
View offer
Growlush Growlush hammer lug crimper

Rank 3

Growlush Growlush hammer lug crimper
7.8/10about £9.90
View offer
On this page
  1. 1.Prepare the copper conductor
  2. 2.Crimp once in the matching die
  3. 3.A lug that pulls off is scrap
  4. 4.Stop when the cable is part of a fixed installation

Prepare the copper conductor

Cut the end square so every strand reaches the end of the barrel together. Slide the heat-shrink onto the cable before you fit the lug, because you cannot pass it over the palm afterwards. Strip only as far as the barrel is deep. If the lug has an inspection hole, you should see copper there and no sheath. Insulation left inside the barrel stops the die biting the conductor. Push the conductor in until it stops, and hold it there while you move to the tool. A 16 mm² cable goes in the 16 die. If that number is not printed, you do not have a matched step and you should stop rather than guess a nest. The hammer crimper vs ratchet page is where that tool choice belongs.

Crimp once in the matching die

Seat the barrel in the die marked for that mm², with the palm of the lug clear of the jaws. On a rotary tool, finish the stroke so the handles reach the stop the tool is built to reach. On the Growlush hammer tool the listing tells you to strike the plunger with a 2 to 4 lb hammer on a solid bench. One compression is the job. A second squeeze at 90 degrees is a workaround, not the normal method. Look at the barrel before you insulate it. Ears or a flash of metal mean the barrel was over-crimped, and you do not file them off. A barrel that stays round is under-crimped.
Dechengbao Dechengbao HX-50B single crimper

Testsieger

Dechengbao Dechengbao HX-50B single crimper
9.4/10about £22.99
View offer

A lug that pulls off is scrap

Grip the cable and the lug palm and pull by hand. If the conductor slides, creeps, or comes out, cut that lug off and start with a new one. Do not add heat-shrink and hope, and do not call a sideways second crimp a repair. A hand tug is a stop rule for a lead you can remake. It is not an IEC 61238 type test, and it will not find every weak joint, but it does catch the failures already written up on these listings. On the Polegas kit, UK reviews say 16 mm² cable pulled out on the 16 setting, and stepping down to the 10 die flattened the lug. Shrink the sleeve only after the tug has held. If you are making battery leads rather than practising the stroke, stud size and current sit on the battery cable lug crimper page.

Stop when the cable is part of a fixed installation

These steps are for a copper lead you can reach again, such as a leisure-battery link on a van or a boat. They are not a method for a joint that will be buried in a wall. Pliers are not that tool. A ratchet printed on a £23 listing does not certify the tool. Stop and get an electrician when the cable is part of a fixed installation, when you cannot identify the circuit, or when the insulation is already cracked. Aluminium power cable is a different preparation. Do not improvise a clean-and-crimp recipe from a copper lug guide. At work, the Electricity at Work Regulations still expect a competent person. If that is not you, the stroke above is not yours to make.

Common questions

Which die do I pick if the title says AWG and the cable says mm²?
Use the mm² on the sheath and on the lug. AWG on these titles disagrees with itself: one 6–50 mm² listing says AWG 8–1/0 and another says AWG 10–1/0. If the die is marked 16 and the cable is 16 mm², that is the setting. If the tool has one unmarked nest, you cannot invent the step. Do not build a conversion chart to force a match.
What if the cable pulls out?
Cut the lug off and begin again with a new lug and a fresh strip. Pulling the same barrel harder, or stacking heat-shrink over it, leaves the failed crimp in the circuit. Polegas reviews describe 16 mm² coming out of the 16 die, and a Growlush review describes a 50 mm ferrule that stayed loose after the die had closed. Both are scrap joints, not joints to insulate.
Is a second crimp at 90 degrees acceptable?
Not as the normal method. One compression in the matching die is the stroke. A second crimp turned through 90 degrees appears in reviews after the first one failed to hold, and it flattens a lug that was already in the wrong die. If the first tug fails, replace the lug. Do not use the sideways crimp to rescue a hammer blow either.
Does heat-shrink fix a loose lug?
No. Heat-shrink insulates and supports the mouth of a joint that has already held under a tug. On the SBGGRL listing, UK reviewers said the tubing was what kept the wire in place, which means the crimp had not. Shrink only after the conductor stays put. If it moves, the sleeve will hide the fault.
What do ears on the barrel mean?
Ears, or a thin flash of metal at the die split, mean the barrel was over-compressed. The opposite fault is a barrel that stays round or shows only a weak mark, which is under-crimped and can pull off. Do not file the ears flat to improve the look. Cut the lug off and crimp a new one in the die that matches the cable. A hand pull will not measure how far over the limit you went.

Related pages

Cable lug crimper

Battery cable lug crimper for camper and boat leads

Best cable lug crimper for occasional 50 mm² leads

Cable lug crimper buying guide: size then mechanism

Hammer crimper vs ratchet: which holds a copper lug

Sources

Public sources from the research digest, used for the buyer point of each standard. Shelf prices and star lines are the amazon.co.uk figures in the display file, checked on 22 October 2026.

  1. BSI, BS 7609:1992+A2:2009, uninsulated compression connectors (retrieved 22 October 2026)
  2. Electricity at Work Regulations 1989 (retrieved 22 October 2026)
  3. HSE, work on electrical equipment (retrieved 22 October 2026)
  4. IET Wiring Matters, March 2020, terminal joints (retrieved 22 October 2026)
  5. Power and Cables, Cembre crimping steps (retrieved 22 October 2026)
  6. IEC 61238-1-1:2018, connector type tests (retrieved 22 October 2026)
  7. E-Tech, BS 7609 and BS 7727 (retrieved 22 October 2026)
  8. Eland Cables, crimp and lug testing (retrieved 22 October 2026)