Hi, I'm looking for advice on drilling a hole in paving blocks (std UK 200x100x50mm) to install a recessed light fitting. Assuming the hole is drilled into the centre of the block what is the maximum diameter hole I can drill without risking the block breaking either during the drilling or in situ later? I don't want to select a light fitting that is too big and cause the blocks to break. Thanks!
Cutting holes in paving blocks
- Thread starter mikeuns
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Bed the blocks on screed concrete, that will be directly beneath the light standards.
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The block is 100mm wide? I don't think I'd drill a hole much larger than 30mm if the block is taking traffic
I managed this by using a diamond tipped tile drill, believe it or not......I kept the block well cooled with water and did it with the block in a vice.
The drill was goosed afterwards though!
John
The drill was goosed afterwards though!
John
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For the most part, you can arrange the cable exit so that it lands between blocks, meaning you can angle grind a wee bit of material off each block.I managed this by using a diamond tipped tile drill, believe it or not......I kept the block well cooled with water and did it with the block in a vice.
The drill was goosed afterwards though!
John
My concerns would be with actually fixing the light fitting down and the risk of at least one of the fixings being close to the edge of a block - and splitting. Hence my recommending that the blocks located by the cable exit, be bedded on screed mortar so that a longer screw can be plugged into the concrete, rather than risk splitting the block.
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For the cost of a drill bit vs the cos of a paviour I think I'd try a regular masonry bit first!I managed this by using a diamond tipped tile drill, believe it or not......I kept the block well cooled with water and did it with the block in a vice.
The drill was goosed afterwards though!
John
Mm, we could perhaps do with more of an idea about the blocks, the proposed lights etc.
Maybe best to drill a close hole and resin fix the light unit in.. Lot of unknowns on this one atm
Conc' paviours drill fairly easily. They don't like expanding plugs in them though.
Thanks for these comments. The 12v light fitting I'm considering would require a 55mm hole to be drilled in the paving block. I was thinking of drilling this hole in the centre of the block leaving approx 22mm of block to the long edge on each side but was worried this would be too thin. I like the idea of placing the light at the joint of the pavers then presumably I could grind out the semi-circle at the end of each block? This would seem to be more robust? The situation is that these blocks make up a path approximately 50m long and to illuminate the path at night I'll need to install in the order of 18 lights! The lights will sit in the hole. Any further comments much appreciated. Thanks.
Correct. Makes more sense than coring a 55mm hole in a pavior.
I did try a regular masonry bit, but I only got to around 16mm before the block cracked......mike needs 30mm which is even more difficult.
Anyway, the blocks I did (2) were drilled by me and then given to the punter. I don’t know what he fixed into them or how they were wired.
John
Switch off hammer mode on the drill!
I'd have doubts about any ground level lights. Don't they all end up full of water eventually?
I'd have doubts about any ground level lights. Don't they all end up full of water eventually?
They seem to end up full of water one way or another. Possibly not from rainwater, just an accumulation of condensation from changing temperatures, from the air.
If the box was completely sealed then it would need to withstand pressurisation when it gets hot and the air inside expands, so there's usually a vent hole.
Many outdoor above-ground electricals have the vent hole in the bottom, so it also serves as a drainage hole - you accept it will gather so you just let it drain out when it does. This is impossible to do underground without that hole also being a groundwater entry point.
Whatever you fit, ensure the whole thing can be replaced if it becomes a gnarled lump of corrosion.
If the box was completely sealed then it would need to withstand pressurisation when it gets hot and the air inside expands, so there's usually a vent hole.
Many outdoor above-ground electricals have the vent hole in the bottom, so it also serves as a drainage hole - you accept it will gather so you just let it drain out when it does. This is impossible to do underground without that hole also being a groundwater entry point.
Whatever you fit, ensure the whole thing can be replaced if it becomes a gnarled lump of corrosion.
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