What size mason drill bit/Tapcon screw to fix sunken box's ?

[bilabonic]

Hi All

I have always found it hit and miss with drill bit size and the Blue tapcon screws when fixing back box's......

I don't want to drill small pilot (which will go through box holes/4mm), remove metal clad, then drill a 6mm hole, the fit a plug, then fix the socket with standard screw.....

I just want to drill through the box with a mason bit that will fit the hole size in the box's, then go straight in with a Tapcon/self cutting screw.

What do you sparkies use ?

I will be going into brick mainly BUT some places are dense concrete block.

Cheers

 

[Taylortwocities]

mark box fixing holes, 6mm drill, red wall plugs.

Tapcon screws are the devil's children.

 

[bilabonic]

That's what i have been doing...Was hoping for an easier/quicker solution..

Why don't they make the bloody holes in the box's bigger so a 6mmscrew/plug can go straight in ?? With a large headed screw

 

[333rocky333]

Most electrical wholesalers round here only seem to sell 1 1/4 and 1 1/2 no 8 countersunks, i have never understood why, seems they think we use them for everything.

Eddies used to sell rounhead No10 spax and said there was no demand

 

[Taylortwocities]

I had a sparky mate who was pulled up on his NICEIC assessment for using countersunk screws to secure backboxes. He was TOLD there was a chance of sharp edge on the screw snagging the insulation on the conductor.

He was told that only roundhead screws were acceptable

 

[JohnW2]

Most electrical wholesalers round here only seem to sell 1 1/4 and 1 1/2 no 8 countersunks, i have never understood why, seems they think we use them for everything.

I think I probably do (use them for {almost} everything) RH screws would probably be more appropriate in many cases, but I often don't have (m)any around!

Kind Regards, John

 

[Risteard]

I had a sparky mate who was pulled up on his NICEIC assessment for using countersunk screws to secure backboxes. He was TOLD there was a chance of sharp edge on the screw snagging the insulation on the conductor.

He was told that only roundhead screws were acceptable

Countersunk should only really be used with spacer bar saddles.

 

[RF Lighting]

5.5mm drill bit, red plugs and either 1½" or 2" no.10 wood screws will give you a good fix in 80% of walls.

The other 20% is a bit more difficult and will require things like expanding foam to get a good fixing.

 

[JohnW2]

5.5mm drill bit, red plugs and either 1½" or 2" no.10 wood screws will give you a good fix in 80% of walls.

I agree about the 5.5mm drill and red plug - but will a 10 gauge wood screw necessarily go through the holes in an average back box?

Kind Regards, John

 

[flyingsparks]

You can blast a 5.5 drill right through the hole in the box then tap a red plug through and do up. Ok so the bit may not last quite as long but they certainly last me plenty long enough to warrant doing this.

 

[flyingsparks]

mark box fixing holes, 6mm drill, red wall plugs.

Tapcon screws are the devil's children.

OOI what's wrong with tapcon screws? Seen them but never used em!

 

[JohnW2]

You can blast a 5.5 drill right through the hole in the box then tap a red plug through and do up.

Oh - I thought I was probably the only person who did that - so I didn't dare mention it here

Kind Regards, John

 

[sparkwright]

Most boxes have holes large enough to pass a 5.5 mm drill bit through, though some don't.

 

[RF Lighting]

5.5mm drill bit, red plugs and either 1½" or 2" no.10 wood screws will give you a good fix in 80% of walls.

I agree about the 5.5mm drill and red plug - but will a 10 gauge wood screw necessarily go through the holes in an average back box?

Kind Regards, John

Yes no problem at all

 

[JohnW2]

... will a 10 gauge wood screw necessarily go through the holes in an average back box?

Yes no problem at all

Fair enough - thanks. I just wondered, and I'm not sure whether I've ever tried (unless, perhaps an 8 gauge one had become loose in its plug!).

Kind Regards, John