Best Cable Knockout Punches for Consumer Units: 2025 Expert Review
Oli at OR Electrics
Fully Qualified 18th Edition Electrician
Since the introduction of Amendment 3 to the 17th Edition (and continuing into the 18th), domestic consumer units in the UK must be made of non-combustible material—essentially steel. Whilst this improves fire safety, it makes creating cable entries significantly harder than in the old plastic days.
Drilling large holes in a metal enclosure creates hot metal swarf that can drop into delicate RCBOs or AFDDs, potentially causing faults before you've even energised the board. This is where a quality knockout punch becomes essential. It creates a clean, burr-free hole with zero debris entering the enclosure.
In this review, I'll compare three knockout solutions I've looked at: a handy manual plier for plastic trunking, a heavy-duty mechanical kit for steel, and a hydraulic set for when you need to save your wrists on a big rewire.
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Specs vs. The Real World
The Spec: "Burr-Free Claims"
"Manufacturers claim every hole is perfectly smooth and ready for a gland immediately."
Whilst 90% cleaner than a hole saw, mechanical punches can sometimes leave a slight lip on thicker steel enclosures. Always run your finger (carefully!) or a file around the edge to ensure the IP rating of the gland isn't compromised.
The Spec: "Effortless Operation"
"Marketing suggests you just tighten a bolt and the metal pops out."
On a manual wrench punch, cutting a 32mm hole in a quality metal fuse board requires significant torque. If you're doing a full board change with 10+ entries, your wrists will feel it unless you go hydraulic.
My Top 3 Recommendations
Three options to cover different needs and budgets
CONQUER 10mm Manual Knockout Punch Pliers for Electrical Boxes & Plastic
CONQUER
This isn't for the main steel consumer unit itself, but it's a lifesaver for the surrounding plastic trunking and pattress boxes. If you're bringing cables into a board via PVC containment, these pliers allow you to nip out a clean 10mm entry in seconds without reaching for a drill.
The Good
- Zero mess – no plastic shavings everywhere
- Extremely fast for multiple small entries
- Ergonomic handle reduces fatigue compared to navigating a knife
The Bad
- Limited to 10mm size
- Not suitable for thick steel consumer unit walls
Installer Tip:
When running surface trunking to a consumer unit, use this to create your cable exit holes in the trunking. It's much neater than using side cutters and leaves a perfect edge that won't chafe the cable insulation.
Priced at £23.40 at the time of writing
Check Price on AmazonDIKTALK Knockout Punch Kit, 6 Size (7/8" to 2-7/16") Forged Alloy Steel
DikTalk
For a solid mechanical punch that won't break the bank, this DikTalk set is impressive. The forged alloy steel construction means the cutters stay sharp even after tackling multiple steel enclosures. It uses a wrench/ratchet system, which is reliable and requires no maintenance.
The Good
- Creates incredibly clean holes in steel conduit and enclosures
- Heat-treated alloy steel allows for long-term durability
- Comes in a sturdy case to keep the van organised
The Bad
- Requires manual wrenching which can be tiring in tight spots
- Sizes are NPT (US standard) – check your gland sizes carefully before punching
Installer Tip:
Always apply a little cutting paste or light oil to the draw stud threads before use. It significantly reduces the friction and effort needed to punch through the steel, and prolongs the life of the tool.
Priced at £79.72 at the time of writing
Check Price on AmazonAMZCNC 8T hydraulic knockout punch electric cable duct hole cutter set
AMZCNC
If you are upgrading consumer units regularly, a hydraulic punch is a game-changer. This tool solves the problem of trying to turn a wrench in a cramped cupboard. The 8-tonne hydraulic force punches through metal effortlessly, and the rotatable head lets you get into awkward angles.
The Good
- Hydraulic action requires minimal physical effort
- Includes metric dies (22mm, 27.5mm, 34mm etc) suitable for UK glands
- Prevents the 'slip and scratch' risk common with manual wrenches
The Bad
- Heavier to carry in the tool bag than a manual set
- Higher upfront cost (though pays for itself in time saved)
Installer Tip:
When using the hydraulic pump, release the pressure immediately once the 'pop' occurs. Continuing to pump after the hole is cut can damage the die or the hydraulic seals. The metric sizes here are perfect for standard 20mm, 25mm, and 32mm glands.
Priced at £110.70 at the time of writing
Check Price on AmazonFrequently Asked Questions
Why shouldn't I just use a hole saw for consumer units?
Do I need a pilot hole for these punches?
Are these tools suitable for the new Amendment 3 metal boards?
Can I use these on stainless steel?
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