chasing in surface mounted boxes.

[danlightbulb]

Hi,

Almost all of my light switches and sockets are surface mounted.

As I decorate each room I want to convert to flush ones.

Is there any reason why they were all surface mounted in the first place?
Is the conversion just as simple as removing the box, stitch drilling and chiselling out a hole for a metal backbox.
Is it safe to assume that if the cable can reach into a surface mounted box then it will easily be long enough for a flush box.

Cheers
Dan

 

[holmslaw]

..

 

[daytona]

dont forget to earth the backboxes/metal switches etc

 

[RF Lighting]

The surface boxes were fitted to avoid damage to the decorations

They are quite common when doing the work to a cost is of major importance.

It is much quicker to fit surface boxes than it it to chop in flush boxes and make good afterwards.

 

[Steve]

Some of our walls are only 6cm thick including plaster - built of thermalite blocks. But we have had no trouble chasing in a switch and several sockets. I can understand why you wouldnt want to chase into thermalite though. Its very very crumbly.

PS we used building adhesive to hold the metal boxes in their holes while the plaster set.

 

[Chri5]

Some of our walls are only 6cm thick including plaster - built of thermalite blocks. But we have had no trouble chasing in a switch and several sockets. I can understand why you wouldnt want to chase into thermalite though. Its very very crumbly.

PS we used building adhesive to hold the metal boxes in their holes while the plaster set.

6mm is 1/4 of an inch (well under that) .

You can't have walls that thin, or are you talking about the thickness of the plaster and render over the bricks / block work?

 

[Steve]

only 6cm thick

6mm is 1/4 of an inch (well under that)

Read it again.

 

[danlightbulb]

Looking at the different metal backboxes, I notice that there are several depths to choose from: 16mm, 25mm, 35mm, 47mm.

Which depth would be best for a) a single gang light switch and b) 2 gang 13A sockets on a 2.5mm T&E ring main.

Obviously want to minimise chasing but need room to wire cables and take the depth of the fitting. I don't intend to use the very flat types of socket (you know the ones that are almost flat to the wall).

Many thanks

 

[Steve]

a) 16
b) 25

 

[daytona]

dont forget,if your going to fit a dimmer you will need a deeper box

 

[danlightbulb]

Thanks all,

looks like 25mm all round then as i do want a dimmer.

Cheers
Dan

 

[RF Lighting]

You're not intending to use flat plate metal accesories are you?

 

[plugwash]

The traditional rule was to use 16 for lightswitches and 25 for dimmer/sockets/20A switches/fused spurs/etc. Going one size deeper (e.g. 25 for lights, 35 for sockets) will make the wiring much easier especially if the box is crowded and it allows for flat plate accessories.

47mm boxes are used for cooker outlets and the like, you shouldn't need them for a socket or similar unless you have unusually big cables coming in.

 

[ColJack]

You're not intending to use flat plate metal accesories are you?

I don't intend to use the very flat types of socket (you know the ones that are almost flat to the wall).

lost the reading glasses RF?

 

[securespark]

Sometimes, surface boxes are used for a good reason.

When I was S/E, one of my customers wanted surface boxes flushing. I could not do it, because underneath were the original (excellently installed) cast switch boxes & conduit...