We've just recently been able to get plastic back boxes here in Cyprus (they have been exclusively galvanized steel until now).
Are these approved by BS7671?
They have no BSBI marking; just 'CE AP3020'.
There is no indication of the type of plastic; hence flammability, etc. is not apparent.
My photos show a double box, with a very handy, tight-fitting, temporary insert.
As you can see, they incorporate glands (16 & 20mm, not 25), have two adjustable bolt pillars, and no little holes for back-filling mortar/adhesive to weep through. The glands also provide some anchoring in the mortar, irrespective of whether conduit is present.
Are these approved by BS7671?
They have no BSBI marking; just 'CE AP3020'.
There is no indication of the type of plastic; hence flammability, etc. is not apparent.
My photos show a double box, with a very handy, tight-fitting, temporary insert.
As you can see, they incorporate glands (16 & 20mm, not 25), have two adjustable bolt pillars, and no little holes for back-filling mortar/adhesive to weep through. The glands also provide some anchoring in the mortar, irrespective of whether conduit is present.