plastic 75mm surface mounting square accessory box?

[Robin]

Is there such a thing pl?

Background is that I want to mount the receiver for another wireless thermostat (after success with 2 aged relatives thanks to advice here). The cable's all on the surface so I thought I could just use a pattress. No go: the (industry standard) backplate is too small for that. It does work with a metal 75 mm "back box" (ie the sort you plaster in for flush mounting). But I can't find the surface mounting equivalent of that. Some manufacturers refer to a "conduit box" but I've not found one in plastic which is 75 mm as opposed to 86 or 87 mm and have square eyes from looking.

[Dave Liquorice]

I think you have fundemental misunderstanding. A stick it in the wall box is as you say about 75 mm sq with accessory mounting holes at 60 mm apart. A surface box is about 88 mm sq but again with 60 mm spaced accessory spaced mounting holes.

The surface box is bigger to match the size of the accessory plate, flush boxes are smaller so that the accessory plate covers the edge (gap) between box and wall material.

Also bear in mind that the front of a surface box is effectively the same as the face of the wall. Just had a fiddle here with flush and surface boxes and a "standard" thermostat plate can't see a problem other than with some surface boxes the plate doesn't have much edge to rest on to stop it dropping into the box.

[spuorgelgoog]

Could you link to the back box it does work with, as I'm not sure what you mean.

Is this of any use

This is the MK box range

Owain

[Robin]

The backplate dropping into the pattress (so the receiver cannot be attached) is exactly the problem I had with the pattresses I had and with all that Toolstation had in stock yesterday. I ran out of time before I could cross the road to Screwfix.

And while this is a Danfoss I that Drayton (and some other brands possibly the same factory) state explicitly "DO NOT use a surface mounting box". I had assumed the reason for that was mechanical. Can it possibly be electrical when they have cut-outs for cable clipped direct to the wall??

[Robin]

Thanks: that looks reassuringly like the piece of thin MDF I bodgered this morning in order to cable to the backplate, mount the receiver and check it all works :)

I hadn't seen anything in that which really suited. And I'm beginning to think I need to make the trek[1] to a TLC-Direct counter and grovel.

[1] by London standards - it's over 8 miles!

[Tricky Dicky]

If your wireless thermostat has mounting holes that match standard back box es why not get a blanking plate drill a hole in the centre to pass your cab les through from the surface box. Then simply mount your thermostat on top of the blanking plate passing the fixing screws through the thermostat thro ugh the blanking plate into the surface box, in effect clamping the blankin g plate between the thermostat and the surface box but crucially providing a base against which your thermostat sits on. This will add about 7mm to ho w far the thermostat protrudes from the surface box, if the mounting screws end up a little short longer ones are available at your local DIY shed.

Richard

[spuorgelgoog]

Agreed, but some flex outlet plates have a front face knockout for cable exit which may be easier than smashing a plate.

Owain

[harryagain]

Google "surface mounted metalclad switches". They are the same size as standard switch frontplates, ie bigger than the box for sinking in the wall.

[Dave Liquorice]

Ah, thinking about how I solved this problem 10 years or so ago. I used a double surface box, double blank plate (the thermostat was about that size, bigger than a single). Fixed mounting plate to blank plate, such that the thermostat was neatly positioned, using the standard 60 mm holes. Drilled large hole for cables in appropiate position. Normal mounting screws blank plate to surface box.