Quick question - screwdriver bit width for electrical fitting screws.

Jul 11, 2019 Last reply: 7 years ago 11 Replies

Having replaced my dud little electrical screwdriver with the cheapo MacAlister one from Screwfix I am now searching for the best bit size for slotted screws which are in light switch and 13A sockets.



Measuring the width they look to be about 7mm.



So do I co for a 7mm bit, or slightly under size with a 6mm bit?



I seem to be awash with Posidrive bits at the moment but not ones for slotted screws.



Cheers


Dave R


Grind a pozidrive bit down to a flat bit of your desired size.

I bought a set of flat bladed bits off Ebay ranging from may be 3mm to

8mm for a few pounds, with long round sections after the hex part.

Quality seems OK.

(I also found some other bits with extended shanks- torx, hex, Pozi, ....)

I would never use an electric screwdriver on such screws (machine bolts IMHO).

'Machine screws' is surely the right term for them isn't it?

Regarding the right sized screwdriver I find that a 4mm wide flat blade screwdriver works well for most electrical work. Occasionally one needs one smaller or larger but 4mm seems good generally. Having said that 4mm is quite an unusual size, it doesn't tend to come with sets of screwdrivers.

Neither, too big. And as almost said, power driving slotted screws just doesn't work very well. The smaller the bit the more stable it is, so try 4 or 5mm.

NT

Screwfix call them electrical screws.

Since may will sit in a small recess, you need a driver that is slightly under the full width - otherwise you will catch on the edges of the recess.

M3.5 screws in electrical accessories are never tightened to anywhere near their load limit, they'd break plastic if they were. There is thus no need for a large bit. Large slotted bits are much more unstable than smaller ones.

NT

I'm following the example of our electrician, where the time saved winding screws in and out of multiple fittings builds up remarkably quickly.

This isn't some massive drill/driver, but a 3.6V one with a torque control.

So far it has worked well for me apart from the bit being too small to easily centre.

Cheers

Dave R

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