The small diamond wheel - 85mm sounds like a solution lads - however I'm not over keen on running dry diamond wheels in grinders as the dust is a issue - even with a mask and safety glasses - unless its a small one off. I certainly would not be happy changing a blade over in a wet saw just for a single switch box.
There are better alternatives, in my opinion. Ie a Rubi N200 / ND 200 as per Dave's post, or a Rotozip saw or a Fein cutter with a diamond blade.
The reason I like the table top saw as well is this - - -
When you want to cut -say a switch box [either whole or part in a tile] then using a Rubi Table saw - or any table saw for that matter, you plunge the blade from underneath [back] of the tile and then you will end up with a neat accurate cut into the corners due to the curvature of the blade. Whereas if you plung it from the face of the tile, whether you are using an overhead D24000 or similar overhead machine or even an angle grinder, you cut to the pencil marks on the tile face and stop at the corner. The tile breaks as it gets too weak and you end up with a triangular nib in the corner to break out with either nippers / file or something else - pain in neck - - - Now I know it sounds petty, but it can take time and effort and sometimes you break the tile after your careful work, just trying to remove this nib.
The thing I like about this forum and this type of debate is - You can exchange ideas and methods and by doing so develop your skills and approach to issues and realise that there are several methods of achieveing the result you need, some suit you and product and some don't. What it does [to me at least] is create a method of self-thinking of - Here's an issue, how can we overcome this ? and what do we need to do to achieve the end result ? Can we do it better ?
PS - Dave will be pleased to hear that I bought a Fein cutter from Tile Trader recently as I am often working on a job and thought - what I need now is a Fein - I haven'y used it yet but no doubt will.:smilewinkgrin:
Thanks