Andrew Gabriel coughed up some electrons that declared:

In article ,
Mike Clarke writes:

MK list special back boxes for their grid switches, e.g. item no. 892 for
flush mounting the 3 and 4 gang grids. Is there some subtle difference
that prevents the grids being used with "normal", and cheaper, boxes? A
plastic dry lining box would be more convenient for a task I have in mind
but I was wondering if the grid would seat properly on it.

I've never used a special MK backbox for gridswitch mounting
a single row. When you're screwing the row into the box, there's
very little extended metalwork to screw up flush against the wall,
and if the plaster around the box isn't perfect, you can find you
have nothing to screw it up tight against. In that case, screw it
up so it would be level with the wall finish (if the wall finish
had been present in the right place), and then screw about half
or one turn further. Now when you screw the facia onto the grid
row, it will be the edge of the facia gripping the wall, rather
than the edge of the grid row, but that works just fine IME.


I just phoned GET about their grid dimmer modules and asked the same
question - in my case: "Why do you sell special back boxes, wouldn't 35mm
standard boxes be OK?".

The technical answer was, yes it would fit a standard box as you say
Andrew - but the bloke also said that they require deeper boxes for the
dimmer modules to allow for heat dissipation. I think their grid boxes are
42mm deep - but he said, of course I could use a standard 47mm box if I
wanted.

So back to the OP: do you want dimmers? If not, I think 35mm standard boxes
would house most modules quite happily.

Cheers

Tim