What size drill bit, wall plugs and screws to fit flush box

25 Jun 2014
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Tyne and Wear
United Kingdom
Hi, i am going to be doing cable runs and fitting some electrical flush mounting boxes but i am unsure as to what size drill bit to use for the mounting box holes then what size wall plugs and screws to use to fix it to the wall. Can anyone enlighten me please?
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I'm surprised you need to ask, really. Personally I use 6mm drill, red plugs and 1½" no 8 screws.

Do not forget to fit grommets in the cable entry holes.
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Also reading up on the legal aspect of installing electrical systems within a domestic property, circuit design, the protective device selection (note 30mA RCDs for newly buried cable and new socket outlets).
Inspection and testing procedures and the much loved documenting of your findings within the relevant forms.

But I tend to use 6mm masonary drill bit, red plugs and a bit of dry wall adhesive to set backboxes on to uneven surfaces, if required.
SDS yes use 5.5 any other sort of drill use 6.

I tend to go with yellow plugs now as with power drivers you can throw no 8s into them quite quickly.
I use a 5.5mm drill bit, red plugs and 1 1/2" no 10 screws normally.
7mm bit and brown plugs.

I only use brown because for some reason I have a big sack of them.

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