First fix back box

stephen_lowfield · 2026-01-13T22:28:13+0000

Hi all, I am going to be doing the first fix electrics in my self build then get my electrician to hook it all up. I want to use 47mm back box on some as going to be adding shelly modules to it also. I will be dot and dabbing plasterboard. How deep do the chases need to be in the blockwork/bricks for these?

flameport · 2026-01-13T22:44:54+0000

For standard plasterboard and adhesive, leave about 20mm out of the wall, so the recess would be about 25mm for a 47mm box.

stephen_lowfield said:
then get my electrician to hook it all up

Has the electrician already been found and agreed to this?

stephen_lowfield · 2026-01-13T22:49:34+0000

flameport said:
For standard plasterboard and adhesive, leave about 20mm out of the wall, so the recess would be about 25mm for a 47mm box.

Has the electrician already been found and agreed to this?

Thank you flameport. Yeah the electrician is my cousin and has told me what needs to be done. Just keeping costs down to a minimum for me. But forgot to ask him the question

Sureitsoff? · 2026-01-14T07:54:33+0000

If you can use those 47mm boxes everywhere it gives more room for the cables and now is the easiest time to make the choice

stephen_lowfield · 2026-01-14T07:58:56+0000

Sureitsoff? said:
If you can use those 47mm boxes everywhere it gives more room for the cables and now is the easiest time to make the choice

Thanks Sureitsoff. That’s my plan

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First fix back box

stephen_lowfield

flameport

stephen_lowfield

Sureitsoff?

stephen_lowfield

DIYnot Local

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