View Full Version : cut hole in concrete block

23rd October 2005, 09:50 PM
Hi all,

I am about to embark on building a small retaining wall, and am using the lock block system from C&M Brick.

I need to recess into this wall several lights to light the stairs built into the retaining wall.

Every light I have looked at requires a hole about 132mm deep with a diameter of 65mm (the blocks themselves are 200mm deep and solid concrete).

There are surface mount lights out there but won't provide the kind of light I require.....

My question is:

Does anyone know how I would be able to bore a hole of this size in these blocks? Can you DIY or is it better to take the blocks somewhere to do it? (and if anyone knows anywhere that would do it)

I need about 10 done.


23rd October 2005, 10:17 PM
This is a little bigger at 82mm but may give you an idea
EBay (http://cgi.ebay.com.au/82x150MM-DIAMOND-CORE-DRILL-SET-NEW_W0QQitemZ7555390514QQcategoryZ1268QQtcZphotoQQcmdZViewItem)

23rd October 2005, 10:22 PM
You could probably hire a Ramset Drill and a core cutting bit from Coates or Kennards Hire.

23rd October 2005, 10:44 PM
Are we talking about link wall paving type stuff that is laid without mortar.
If so this little black duck woun't be fixing any thing with 240v power to them or in them.

23rd October 2005, 10:47 PM
soundman - Yes we are talking about the mortar less retaining walls - can you explain why you wouldn't connect lights to these ?

23rd October 2005, 11:13 PM
Just think about it.
The only thing holding that wall together is gravity.
Someone can come along at anytime and just unstack the bricks.
Now I don't remember seeing anything specific in the regs regarding this but there is an implied expectation that any elecrtical item is securely and permanently attached, further it is expected that a "tool" be required to open or remove any electrical fitting.
To my thinking a stack of bricks isn't secure or permanent.
I would expect that any electrical item would need independant and permanent support other than this type of wall.

such as a galvanised metal bracket set in a secure concrete foundation.

The other option would be to go low voltage.

I can tell you in my travels I have seen plenty of these walls and lots that are not in the condition that they were laid. These things move, if not by themselves by other causes.

hope you understand

23rd October 2005, 11:17 PM
If you're contemplating 240V lighting you should be looking at waterproof housings and armoured conduit.
Me I'd be looking at a surface mount 12V system. Surface mount lighting seems to work fine for Taronga Zoo.


23rd October 2005, 11:28 PM
Ian, Soundman,
Yes the lights are low volatage... sorry should have said that.
I see your point about movement - I have buillt 5 or 6 of these walls successfully in the past with little to no movement, and usually bond the blocks together with some form of glue (taking one apart requires significant effort... as I recently found out)


23rd October 2005, 11:38 PM
you could hire a core drill and bit or buy yourself a 65mm plumber's hole saw to cut a neat hole in the face of the block and then drill a series of " holes and use a chisel hammer to rough out the rest of the hole.
Still think searching out a surface mount light would be easier.


23rd October 2005, 11:46 PM
In that case.
Any respectable concrete cutter should be able to do the job for you. or you may be able to hire a corring drill to do the job.
you would just need to contrive a way of holding the block.

24th October 2005, 04:25 PM
Do you reckon making a mould out of 65mil PVC pipe and ply and then casting some, would look any good?

Or you could try this method if the lights come with a flange to cover the rough hole.

24th October 2005, 11:07 PM
get the local conceret cutter in to do it or drop them over to there place, do not hire as they charge lilke crazy and if its a rough face you will have trouble getting the hole started.