Fitting a flush grid switch..

[icarusbop]

Hello:

I am going to be fitting a flush grid switch with 4 modules
This is the first time I have done this.
since in a grid system the switch modules are fixed to the backbox not the front plate - it seems the depth of the backbox in the wall is more critical to ensure a nice finish on the surface.
eg, if the box is too deep, I assume the coverplate will not fit nice and flush to the grid modules.
I am going to be tiling the area, after a worktop is finished. Theoretically I need to fit the backboxes first, but assume they now need to be 'proud' from the wall so they are flush with the tiles, when the tiles are fitted.
My question is - is there any method of adjusting the depth of the grid modules on the grid plate, so they can be made nice and flush to the coverplate when it is fitted? If how, by approx how much can they be adjusted?

Thanks

Ian

 

[holmslaw]

..

 

[icarusbop]

Now I've had a closer look at the grid plate - it makes sense.
Thanks for the info.