Old British Standard back boxes incompatible with new electrical screws

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Hi,

I'm at the tail end of redecorating my flat, and I have replaced most of the wall plates for power and light switching to new MK Logic plus stuff. The metal wall boxes for the power outlets were fine, but I have noticed that the light switch plates use an old (British Standard?) metal wall box, which seems to have had a larger gauge fixing screw ( the two that secure the face plate to the metal wall box).

The ones that came with the new light switch plates are too small a gauge, and will therefore not secure the wall plate to the wall.

The building is mid-1960s, and the metal wall boxes are original (I did not replace these, as they are firmly anchored to the original metal conduit, and the electrics megatested ok). Unlike the modern ones with a metal piece that takes the wall plate screw, these have a plastic piece that does that job, and the screw was larger. The wall boxes are in fine condition.

Is there a modern equivalent to these screws which are readily available. Seems a shame to put back the old screws, and I may have lost a couple. I would say they are 0.5 gauge or so larger than the modern ones supplied (but likely an old imperial size).

Thanks in advance.
 
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Is there a modern equivalent to these screws which is readily available. Seems a shame to put back the old screws, and I may have lost a couple. I would say they are 0.5 gauge or so larger than the modern ones supplied (but likely an old imperial size).
They are quite probably 4BA screws.

Kind Regards, John
 
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No probably about it, they are 4BA which is actually metric based. What is actually the problem with putting back the old screws? I imagine 4BA screws would be hard to obtain nowadays though I have not actually tried.
 
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... What is actually the problem with putting back the old screws? I imagine 4BA screws would be hard to obtain nowadays though I have not actually tried.
Over 1,700 hits on eBay. Although many are obviously not an appropriate type, I feel sure that something suitable could be found amongst them.

Kind Regards, John
 
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No probably about it, they are 4BA which is actually metric based. What is actually the problem with putting back the old screws? I imagine 4BA screws would be hard to obtain nowadays though I have not actually tried.

I cant seem to find them all at the moment, but other than that, no issue. I need about 6 of them... they don't seem to hard to find.

That's excellent help... i'll let you know if they do the job.
 
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I cant seem to find them all at the moment, but other than that, no issue. I need about 6 of them... they don't seem to hard to find. That's excellent help... i'll let you know if they do the job.
Indeed. As I just wrote, over 1,700 hits on eBay for "4BA screw" - so I feel sure you'll be able to find something suitable amongst them.

Kind Regards, John
 
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They would obviously work but they are not as nice as the origional raised countersunk head type.
 
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May be easier to retap the existing box threads to M3.5 and use new screws
I think one would probably have to squash (if metal) or otherwise 'plug' a 4BA hole before successfully tapping it with M3.5 (the OP has said that M3.5 screws are loose in the existing holes). I think the OP mentioned that the lugs are plastic, which makes this a less simple approach.

Kind Regards.
 
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the OP has said that M3.5 screws are loose in the existing holes
Will that cancel out the next problem he will find, which is that 4BA are a tight fit, or quite possibly too big, for the faceplate holes?
 
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The blocks are nylon not plastic I think.
Probably, yes - I obvious;ly meant 'non-metal'.

'Plastic' is an odd word, anyway. Although it has come to be used to refer to polymers, there are lots of metals (e.g. lead and copper) were are essentially plastic (as opposed to elastic)!

Kind Regards, John
 
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Will that cancel out the next problem he will find, which is that 4BA are a tight fit, or quite possibly too big, for the faceplate holes?
I know for a fact you have to drill them out for 4mm.
Stupidly I tried to clean up some box threads and mistakenly used a 4mm tap instead of a 3.5mm,
 

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