sealing around back boxes

[sm_jamieson]

Regarding fitting back boxes and eventual sockets / switches etc. I understand that a gap is allowed between the metal back box and the socket / switch (the old "using long screws" etc). But what are the general rules about this gap ? The gap can be quite large after a previously untiled wall is tiled for example. Generally must be fireproof ? Is there are maximum gap allowed ? E.g. If you end up with a slight gap between the metal back box and plasterboard dry lining (say up to 15mm gap), is the general method to shove in some plaster / plasterboard adhesive etc into the gap so the plasterboard so the socket is roughly sealed from the gap behind the plasterboard ? Cheers, Simon.

[Tim Watts]

I must admit I have never given the spacinmg betwene the metal box and the plate a second's thought.

Wouldn't worry about this, except in the case of studwork walls wher eit is worth some consideration. if the gap is lined with plaster or PB it's not worth worrying about,

Yep - stuff it with any filler that works.

What matters more are gaps between the plate and the face of the wall, especially the top where kiddies could go poking wires/pins in and zap themselves.

I had a couple of gaps due to curves in the plater finish - had to make it up with filler.