Would a grid switch fit here?

[Steve]

Might sound a daft question. In the kitchen, there is a lightswitch which I want to convert to a gridswitch. But the backbox is recessed "UNDER" a layer of plasterboard. The screws are only just long enough. When the adjacent doorway was blocked up, they just banged up a sheet of plasterboard over the breeze blocks and had done with it. For neatness they carried on beyond this switch.

I guess my question is does the gridswitch frame have to fit against the backbox? Or can there be a "decor" gap as on a normal switch? Never fitted one myself. If needs be I can change the backbox for a 35mm one, I think it would fit.

By the way, how many screws do you use to secure backboxes?

 

[Taylortwocities]

You'll need 35mm from surface to wall. Cant see what you have there is it 16mm box plus 9.5mm palsterboard + skim?

PS. Always two screws.

 

[Steve]

You'll need 35mm from surface to wall. Cant see what you have there is it 16mm box plus 9.5mm palsterboard + skim?

PS. Always two screws.

Yeah, 16mm box and a load of plaster. didnt measure exact, suppose I should have. I think I have a 25mm backbox somewhere, will see if that fits. I dont fancy chopping out any more. If it needs 35mm though, I'll just link out the outside light switch (my intention was to use a keyswitch on it but if its going to be too much trouble I wont bother)

 

[333rocky333]

Mk will fit that I would have thought

I find It is very rare to find the grid tight on the backbox lugs , usually you bring it forward enough so the switch is protruded enough for the faceplate.
You have to balance it right to get the tension to keep the pressure right for the plate to be secure.
Another option is 4mm nuts and washers slid on the screws first and the grid will then fit tight on the box lugs and not move.
They have fitted screws, but sometimes you need to replace with longer ones or use pillars.

If you want, I can do a pic of an Mk one assembled, side on, proberly the weekend if it helps.

PS, All your posts seem to big for the page lately.

 

[RF Lighting]

MK grid frames have little sticky out bits on the two sides. They sit flat onto the plasterwork and hold the assembly in place. It doesn't matter if the box is sunk well into the wall. The only thing you may have to do is cut the srews off from the frame and fit long standard socket screws.

If you are just using normal grid switch modules and you keep your wiring neat, it should just fit with that box.