20mm channelling/chasing for oval conduit using SDS+ drill and Armeg EBS Extended 20mm Channelling Chisel

Hi all,
I've just borrowed my mate's SDS+ drill and purchased the Armeg EBS Extended 20mm Channelling Chisel (from ScrewFix) to begin channelling plaster/breeze block for running 20mm oval conduit to some new boxes (12 ceiling-to-box chases and 12 floor-to-box chases) and I'm just wondering where to start! My electrician has already chased the plaster, which is not thick enough to cover/contain the conduit, which means I have the job of chasing slightly deeper channels in the breeze block (the electrician will not install conduit - only galvanised capping). I require conduit for the low voltage/data cabling to provide flexibility in the future!
Unfortunately, this is my first house and my DIY experience is rather limited! Consequently, I would like to ask the following question(s) (please):
1. What's the best way to mark cutting/chiselling/channelling lines on breeze block that has lots of "lines" from an angle grinder (chalk or something better?)? A big marker pen is fine on plaster, but not on breeze block! 2. Is it best to "score" or "define" the channels/chases (e.g. manually with a cold/bolster chisel) before going in with the SDS+ channelling chisel or can I just put the chisel to the breeze block and follow the marked lines like a maniac (I don't know because I've never used an SDS+ drill)? 3. Do the channelling chisels (or any SDS+ chisel attachment) have a tendency to "wander" if you're not very very careful? 4. Is it likely that I will accidentally channel through into my neighbour's house if I'm not very very (extremely) careful when channelling the breeze block wall? 5. Will a 20mm (wide) x 10mm (deep) ceiling-to-box or floor-to-box channel weaken my breeze block wall considerably? 6. With two channels per box, there's a total of about 70 metres of channelling to do (for the whole house)...Am I being irrational in tackling the job with such tools? 7. Will the SDS+ drill with channelling attachment be quicker (and tidier) than an angle grinder and cold/bolster chisel? 8. Approximately how long does it take to channel 1 metre of breeze block using an SDS+ drill with the correct attachment? 2 minutes? 10 minutes? 1 hour? 9. Alternatively, shall I just get my gloves and goggles on and learn from my first channel!?
Evidently, I consider the conduit to be critical to completing the project, which means I'm willing to complete the work myself...
I would appreciate any suggestions regarding the nature of this work...
Thanks in advance.
Kind regards,
Scott McGowan
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Hi Scott, Relies embedded below - I recently bought one of these (mine's a 40mm I think, but I'm boasting now!) They're good, but need some practice. In breeze block they can be a bit brutal - My drill is a quite a biggie - Makita SuperMak/ 4.5kg. A smaller (less joules of hammer) drill would be better for breeze block. Mine is great for cutting channels in brick + masses quicker than a cold chisel.
Like a lot of these type of tools, practice makes perfect + try a small section first & beware of all the mess.
John

I use my 4'x2" spirt level & mark/score a line down each side of it.

the wall. When chiselling a plastered wall I normall manually chip the plaster top coat with hand chisel first, so Iit comes away more neatly.

afterwards.
engineering bricks then...

angle grinder.

the mess & dust (see next item)!

even better, esp. for use with Armegs box sinker.
PS You can get special wall chasing machines with dust extraction etc. But I have not tried these.
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"McGowan, Scott" wrote

Get a good quality SDS gouge (looks like you have !) that will hold a reasonably sharp edge, i.e. not one of those camembert ones from the sunday market. I paid ~18 for mine.
It will wander, take it slow and plan to take the material out in 2 passes until you're used to it, then you can be a bit bolder.
The angle as has been said before is critical here, too steep and you will knock chunks out of soft material.
Gloves and goggles are useful, as once you start you should continue for a reasonable run rather than doing 6 inches at a time.
Good luck,
Cheers,
Paul.
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