Help With Cutting for Knockout Boxes in Honeycomb Brick Ask questions and find answers to many subjects relating to electrics and electrical work

[Jonathand]

Hi all, I'm getting stuck into renovating a mid 30s semi and installing knockout boxes. The whole house is made of hollow bricks, that are a bit like honeycombe when viewed from the top, except the holes are in straight lines.

Cutting out for knockout boxes is a nightmare as the bricks either disintegrate or just fall away in layers. I've tried using a bolster chisel so far and that hasn't worked. Don't dare try an sds on them. Drilling holes for the plugs for the screws is equally a nightmare as I just find a void and the drill wanders off.

Any advice on how to cut in for the boxes and drilling holes for the plugs and screws?

And what to do with the mess I've got so can install the boxes I've cut for so far. Any help much appreciated.

Image attached for example of what I've done so far.

[ericmark]

There are so many tools, I remember my son having a socket box sinking tool, he said it was great, but when it was stolen he did not replace it, also seen him sticking boxes in place using expanding foam then trimming it next day, not what I would do.

Most electricians have an array of tools, the oscillating multi tool is popular, never to date used one, also angle grinder, but which tool depends on what you have in your tool box.