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Most of my walls consist of solid plaster over masonry, which makes electrical work difficult to say the least. I want to add some wiring to an existing wall in order to add light fixtures to a room which currently lacks them. Since there are no stud bays to run wires, I will need to cut channels in the plaster to run armored cable or conduit.

What are the best tools and techniques for accomplishing this?

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how thick is the plaster? Is there any thing supporting the plaster such as lath or mesh? – mikes Feb 7 '14 at 14:48
How deep do wiring codes require the channel to be, and how must the cable be armored/protected? – DJohnM Feb 7 '14 at 17:43
@mikes the plaster is at least 3/4 of an inch thick based on some exploratory drilling. It appears to be applies directly on top of the concrete block; I'm not sure if there's any mesh or lathe. – friedo Feb 7 '14 at 21:09
up vote 4 down vote accepted

Channelling chisel on SDS drill.

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For short runs a brick bolster works reasonably well (and produces much less dust)

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Deeply scoring the plaster with a knife beforehand to define the edges of the channel may help to prevent large irregular chunks being removed.

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