Fast Fix / Drywall Back Boxes

[rn55one]

Hi,

I am looking for some Fast Fix boxes so that I can wire some plug sockets up.

However, The wall I am trying to put these in is thicker than the average plasterboard wall.
basically, there is a sheet of plywood (15mm thick) then the plasterboard (20mm thick) ontop of the plywood board.

This means when I am using the deepest fast fox box my local hardware place stock, the two tabs either side can not be pushed out as they keep hitting the plywood.
I have searched online, however the only results I can see are deeper Fast Fix boxes, but the 'tightening tabs' still only tighten the same amount.

Ideally I need some fast fix boxes that would operate (allow for the tightening) for around a 30 or 40 mm thickness.

Does anyone know where I can get these? a link would be perfect.

Cheers.

 

[securespark]

Not sure they exist.

Try cutting out some ply where the lugs go with a hacksaw blade.

 

[rn55one]

Yeh I've tried that - really difficult to get the saw blade in.
Ended up damaging the plaster on top.

Surely this must be a 'commonish' issue?

 

[securespark]

Any way you can fix normal boxes?

25mm is the max I can find.

 

[pjcomp]

If you've got that amount of depth to work with and, presumably, a void behind, can you work in a piece of batten across the hole, screw through the wall either side of the hole to fix the batten, then use a standard 25mm knockout box screwed to the batten.

PJ

 

[securespark]

Or even 35mm!

 

[rn55one]

Yes there is a large void behind the hole.

Good idea with the baton - I can then simply fill the holes where the screws are.

 

[securespark]

Well worth a try.

Just hope the box holes are not too close to the studs.