1st fix Chassing and back boxes

[Shocking]

New build 2 storey extension, block internal walls to be plastered over whats best?
1) chase in conduit or
2) surface, metal or pvc channel.
whats the best size metal back boxes to use ie lighting switches using dimmers ( I know the backs of these can vary alot) but customer hasant decided wich ones yet, dont want to put to smaller box on wall and have to change it after plastering? Is there a one size fits all? And how far would you leave back boxes protruding from block work for plastering? cables not in safty zone but will be RCD protected.

thanks for any advice guys.

 

[malcolmsanford]

Put a 35mm in that should cover nearly all dimmers, if you need a 45mm then that is some dimmer.

If block you mean breeze or thermolite etc then if you want it flush you will need to chase it in. IMO chase and then oval tube to protect the cable from plasrerers, but oval tube is not necessary.

Normally only leave back boxes proud if the wall was being dry lined, are they? If it's plaster then cut them flush with the block, unless you think the plasterer is going to welly on loads of coats, for some reason.

Why are you not running in zones? You should

 

[Des 56]

Why are you not running in zones? You should

Same thought,rcd doesn't mean ignore them

 

[Shocking]

Sorry about the zone bit they are run vertically,horizontally from switches and sockets, I meant to say there not 150mm from top of wall and 150mm from corners, oops. one to many Shandy's last night. the walls are thermo lite and will be plastered, a bit like me last night.

sorry for confusion guys

 

[rocker]

Thermolite mate just chase in some oval, you can chase that stuff out with a dessert spoon! Again as it's thermolite and easy-peasy, you may as well use the deepest boxes you can get your hands on.

 

[Hawk81]

Most houses in northern ireland are all done in block walls just plastered and we always use 20mm conduit. it is easier to get cables down than oval conduit. I definitely was use a conduit of some sort I would not be happy with the cables just being plastered into the wall. For the switches I would use 35mm boxes and sockets i would use the 25mm boxes. Leave them nearly flush with the blockwork.

 

[Shocking]

Hawk81 the conduit is chased and flush with blocks?
and is that metal or PVC?
why not use metal or PVC channel and save chassing into the wall?
that was the point of this post.

 

[Hawk81]

Hawk81 the conduit is chased and flush with blocks?
and is that metal or PVC?
why not use metal or PVC channel and save chassing into the wall?

the conduit is chased. the outside edge of the metal box is near flush with the blockwork. conduit is pvc.

 

[Amp David]

Unless otherwise asked for, I would run cables down on the block and use capping to cover, whether drylined or wet plastered.
25mm back boxes surface mount if drylinig, sink in about 15mm if wet plastering.