SDS Plus square electrical box cutter with tungsten carbide blades. Cuts a clean 77 x 77mm recess in brick, breeze block and concrete block up to 45 Newton. For use with SDS Plus rotary hammers with roto stop. Works alongside the BCR77N circular hole cutter.
The square electrical box cutter is the tool that makes cutting socket box recesses in masonry bearable. Anyone who has tried to square off a circular hole with a bolster knows how that story ends. This SDS Plus cutter takes a 77 x 77mm square recess out of brick, breeze block or concrete block in one clean pass, saving the kind of time that adds up fast when you are fitting sockets across a full house or commercial unit.
It mounts on any SDS Plus rotary hammer with a roto stop function, so the hammer action does the work without spinning the cutter. The tungsten carbide blades are up to the job on typical masonry block work, and the kit is designed to be used alongside the BCR77N circular hole cutter. The circular cutter knocks out the bulk of the material first, then the square cutter cleans it up to the correct profile for a standard single socket back box. It is a two-step process, but it is still quicker and far cleaner than any alternative method on block or brick.
Where the Square Electrical Box Cutter Gets Used
This cutter is aimed at first fix electricians working in new build or refurbishment where sockets are being installed directly into masonry walls. It handles brick, breeze block and concrete block up to 45 Newton compressive strength, which covers the vast majority of standard block work you will encounter on residential and light commercial jobs. It is not a concrete-busting tool, but for standard building block it performs exactly as intended.
The SDS Plus shank suits the 2kg class SDS drills that most sparks and first fix tradespeople already carry. No adapters, no fuss. The roto stop feature on your drill locks out rotation so the cutter chisels rather than spins, which is exactly what you need for a controlled square cut in masonry. Keep it paired with the BCR77N and the two tools together give you a repeatable, tidy socket recess every time.
Pro Tip: Always make the circular pilot cut with the BCR77N first to remove the bulk of the material before bringing in the square cutter, attempting to go straight in with the square cutter on solid brick will burn through the carbide blades far quicker.
The square electrical box cutter is used on first fix electrical installations where back boxes need to be set into masonry walls. It is the standard approach for sparks fitting single socket positions into brick and block construction, covering new builds, extensions, and refurbishment work where walls are not being boarded over. It suits any job where a clean, accurate 77 x 77mm recess is needed directly in the masonry.
Best For
First fix electrical installations
Cutting single socket box recesses in masonry
New build and refurbishment projects
Repetitive socket positions across large jobs
Compatible With
SDS Plus rotary hammers with roto stop
2kg class SDS Plus drills
BCR77N circular hole cutter (used as pilot cut)
Brick, breeze block, and concrete block up to 45 Newton
Key Specifications
Recess size: 77 x 77mm square
Shank: SDS Plus
Blade material: Tungsten carbide
Max material strength: 45 Newton
Requires roto stop / chisel mode on drill
Not suitable for: Not suitable for use in dense concrete, reinforced concrete, or any masonry rated above 45 Newton compressive strength. Not compatible with standard rotary drills or SDS Plus drills without a roto stop function.
Start with the BCR77N circular cutter to remove the core material first. This is not optional — trying to cut the full square without the pilot hole puts unnecessary strain on the carbide blades and the drill. Once the circular cut is made, fit the square cutter into your SDS Plus drill, engage roto stop so the drill is in chisel mode only, and work the square cutter into the recess.
Apply steady, controlled pressure and let the hammer action do the work. Avoid forcing the cutter sideways — guide it square to the wall and work progressively around the edges of the recess until the full profile is clean. Check the depth against your back box before finishing off.
Mark the socket position on the masonry wall using a back box template or pencil and square
Fit the BCR77N circular hole cutter to your SDS Plus drill and cut the pilot hole through the centre of the marked recess
Remove the circular cutter and fit the square electrical box cutter to the SDS Plus drill
Engage roto stop on the drill to switch to chisel mode only — do not use in rotation mode
Position the square cutter in the pilot hole and apply steady forward pressure, working progressively around the four sides of the recess
Check the recess depth against your back box and adjust as needed before completing the cut
Clear out any loose debris from the recess and test fit the back box before fixing
Do I need the BCR77N circular cutter as well, or can I use the square cutter on its own?
You need the circular cutter first. The BCR77N removes the bulk of the material and creates the clearance the square cutter needs to work cleanly. Going straight in with the square cutter on solid masonry will overload the blades and shorten their life significantly.
Will this cutter work with any SDS Plus drill?
It needs an SDS Plus drill with a roto stop or chisel-only mode. The cutter must be used in hammer action without rotation. If your drill does not have a roto stop function, the square cutter cannot be used safely or effectively.
What is the maximum hardness of masonry this cutter can handle?
The cutter is rated for brick, breeze block and concrete block up to 45 Newton compressive strength. That covers most standard building block work on residential and light commercial sites. It is not designed for dense aggregate concrete or anything significantly harder.
The cutter body is fitted with tungsten carbide blades, which provide the hardness needed to cut into masonry without rapid wear under hammer action. The SDS Plus shank is the standard fitting for rotary hammer drills in the 2kg class and connects securely without an adapter. The 77 x 77mm cutting profile matches the industry standard single back box footprint used across UK electrical installation work.
Shank Type
SDS Plus
Cutting Profile
77 x 77mm square
Blade Material
Tungsten carbide
Compatible Materials
Brick, breeze block, concrete block
Max Material Strength
45 Newton
Operating Mode
Hammer only (roto stop required)
Recommended Pilot Cutter
BCR77N
SKU
EBC-1
Size
Circluar 77 x 77 mm, Double Box 80 x 140mm, Single Box 77 x 77mm
Box Quantity
1
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