'Recessed' back box?

[JohnW2]

Hi folks,
Over the weekend, a neighbour of mind was replacing a broken double socket, and asked me to 'check that he'd connected it correctly' (it would be pretty difficult not to ). It looked as if whoever had installed it had run out of 35mm metal back boxes, because what was there was a 25mm one, buried with it's front 10-15mm below the wall surface (and, I imagine, longer than usual faceplate screws). I 'commented' on that, but said (as I still believe) that there was nothing particularly 'wrong' with it (and whoever did it had done a good job of making good the edges of the hole, so that they were all well under the faceplate.

Can anyone think of any problem with such a situation?

Kind Regards, John

 

[pete01]

No seems normal to me.

I prefer to put 25mm boxes a bit deeper as I always think 35mm are a bit too deep....just me maybe.

 

[Murdochcat]

Perfectly acceptable solution. 25mm back boxes are the work of the devil.

35mm or 47mm are better

 

[pete01]

47mm are better

Good luck on a single brick wall....

 

[SUNRAY]

47mm are better

Good luck on a single brick wall....

I've worked on a pair back to back in 3" block, rivetted together and only held in place by the faceplate screws.

 

[SUNRAY]

Hi folks,
Over the weekend, a neighbour of mind was replacing a broken double socket, and asked me to 'check that he'd connected it correctly' (it would be pretty difficult not to ). It looked as if whoever had installed it had run out of 35mm metal back boxes, because what was there was a 25mm one, buried with it's front 10-15mm below the wall surface (and, I imagine, longer than usual faceplate screws). I 'commented' on that, but said (as I still believe) that there was nothing particularly 'wrong' with it (and whoever did it had done a good job of making good the edges of the hole, so that they were all well under the faceplate.

Can anyone think of any problem with such a situation?

Kind Regards, John

No problem at all if they are secure.

 

[JohnW2]

Perfectly acceptable solution. 25mm back boxes are the work of the devil.

... except, as you say, it's perfectly acceptable to send the devil away by sinking the 25mm box below the surface!

Whilst I essentially agree with your view, a real 'old-timer' electrician I knew, who died quite recently, in his 90s, used to say that anyone claiming that 25mm boxes were not deep enough "did not deserve to be called an electrician"

 

[JohnW2]

No problem at all if they are secure.

I see no real reason why it should be any less secure than would a deeper box - after all, it's primarily the screws through the back of the box that secure it.

 

[SUNRAY]

... except, as you say, it's perfectly acceptable to send the devil away by sinking the 25mm box below the surface!

Whilst I essentially agree with your view, a real 'old-timer' electrician I knew, who died quite recently, in his 90s, used to say that anyone claiming that 25mm boxes were not deep enough "did not deserve to be called an electrician"

My dad would only buy the cheapest BB so usually the shallowest, many of our single sockets were mounted in the shallow switch boxes buried deep

 

[SUNRAY]

I see no real reason why it should be any less secure than would a deeper box - after all, it's primarily the screws through the back of the box that secure it.

Indeed yes, I mention it only because I seem to find loose boxes tend to be shallow boxes buried deeply

 

[JohnW2]

My dad would only buy the cheapest BB so usually the shallowest, many of our single sockets were mounted in the shallow switch boxes buried deep

Yes, I was tempted to ask how one would describe 16mm ones, if 25mm ones were 'the work of the devil'

 

[JohnW2]

I've worked on a pair back to back in 3" block, rivetted together and only held in place by the faceplate screws.

Quite enterprising - maybe you should patent that idea

 

[morqthana]

Whilst I essentially agree with your view, a real 'old-timer' electrician I knew, who died quite recently, in his 90s, used to say that anyone claiming that 25mm boxes were not deep enough "did not deserve to be called an electrician"

He presumably never encountered dimmers, smart switches, smart sockets, flat-plate accessories, sockets with USB chargers built in, Euromodules.....

 

[plugwash]

Can anyone think of any problem with such a situation?

Two potential concerns spring to mind.

1. Electrical conductivity. An electrical enclosure should ideally be made out of either a good conductor and connected to earth or made out of a good insulator. A material that is neither a good conductor or a good insulator poses a risk in that it may carry enough current to give someone a shock, but not enough to blow a fuse/trip a breaker.
2. Fire resistance, electrical enclosures are supposed to be made of flame retardant materials.

I know gypsum plaster has good fire resistance. I'm finding it hard to find good information on it's electrical conductivity but I get the impresison it varies significantly with moisture content.

 

[morqthana]

And the cables from the back of a socket could come into contact with plasterboard how?