socket back boxes; depth

[cjard]

My wall construction is such that between the OSB that closes my timber frame cassettes (on the inside), and the plasterboard of the wall, there is a 25mm gap (and 10mm+ of plasterboard). The socket box will screw to the OSB

Does this mean I should use a 35mm socket box, to finish flush-ish with the plaster, or is a 25mm socket box acceptable? Not sure if there is any rule about whether a socket face plate should be in contact with/form a lid of the socket back box?

 

[riveralt]

25 or 35mm backbox is up to you - the deeper the better - subject to the building fabric rules.
The socket screws form the link between the earth and the backbox.

 

[securespark]

Put the deepest box you can in. Then if you choose sockets that need 35mm boxes (some skinny-plate accessories or USB sockets), they will fit.

 

[Taylortwocities]

and our plasterer will love you if you give him an edge to plaster on to.

 

[Lectrician]

35mm would be the choice here.

I know others are saying it doesn't matter, deepest you can etc, but they have not read your post fully. You have a gap of 35mm to "fill", a 35mm box would be preferable than a 25mm which would sit just behind the plasterboard. A 35mm will sit perfectly flush with the plasterboard, and once skimmed, would be absolutely pukka.

When normal walls are battened off and boarded, 35mm are the norm, fixed direct to the wall.

 

[cjard]

Thanks all

and our plasterer will love you if you give him an edge to plaster on to.

Following a couple of eyewatering quotes from plasterers, I'm considering alternatives to skimming, but any way round i think a 25mm service void + some kind of board will mean there's always a 35mm gap to fill

Was just curious if there was anything in the regs about a child being able to poke something between the faceplate and the wall and successfully reach a live terminal (which could happen if the face plate was a little loose, and the backbox didn't come all the way up to the backside of the faceplate)

 

[bernardgreen]

It is possible to push thin objects behind face plates if the plate is not touching the back box.

A piece of wood of the correct thickness can be fitted behind the back box to bring the front edge of the box relative to the plaster surface.
Decide which fixing holes in the back box will be used and then drill clearance holes in the wood to match. Tack the wood to the back of the box with a small screw ( or double sided tape if you are never going to remove the box again ) then fix the box to the wall with screws though the clearance hole in the wood.

 

[JohnW2]

Was just curious if there was anything in the regs about a child being able to poke something between the faceplate and the wall and successfully reach a live terminal (which could happen if the face plate was a little loose, and the backbox didn't come all the way up to the backside of the faceplate)

That could happen if "the faceplate were a little loose" even if the backbox were sticking out proud of the surface of the wall - so isn't really very relevant in terms of whether or not the box is flush with the wall.

Kind Regards, John

 

[bernardgreen]

The hazard is that it is possible to push an item through the plaster and and through the gap between face plate and the edge of the box and thus into the back box. If there is no gap between plate and box then getting something into the box is near impossible.

 

[JohnW2]

The hazard is that it is possible to push an item through the plaster and and through the gap between face plate and the edge of the box and thus into the back box. If there is no gap between plate and box then getting something into the box is near impossible.

True, but it's very unlikely that anyone, even a child, would do that. The OP was talking about a situation in which the faceplate screws were loose - in which case, as I said, there would be a gap between faceplate and box even if the box were protruding from the wall!

Kind Regards, John

 

[Taylortwocities]

Was just curious if there was anything in the regs about a child being able to poke something between the faceplate and the wall and successfully reach a live terminal (which could happen if the face plate was a little loose, and the backbox didn't come all the way up to the backside of the faceplate)

As above, there should be no way of doing this if the plate is propely fixed and the wall is reasonably even.

Those so called "Socket Safety Covers" (available in may stores) are much more of a hazard.

 

[bernardgreen]

If the fixing screw is pressing the plate against plaster instead of the metal ( or plastic) of a back box then with plugs being pushed in and pulled out the pressure and vibration will abrade the plaster. The pressure on the thread locking the screw will reduce, eventually enough to allow the the screw to rotate and with further vibration the screw will loosen