How to remove knockouts from this junction box?

I realise that's not a steel box, and you've only got one to do, but I think what would be in most spark's toolbags would be one of these

flared to stop it punching right through.

they do a 25mm version if that's the size knockouts you want to use

That's no use because it will destroy the M20 thread before it even reaches the knockout.

It would be fine for simply making 20mm holes in the flat sides of a box without threaded holes.

I see that's made by CED. I stopped buying Toolstation's CED socket boxes because the plastic was so crudely made that the knockouts on the same box went from being paper thin to being super thick and impossible to push out, or when you pushed out you'd shatter half the box.

However those are thermoset plastic and your box is ABS. But perhaps they share the same lack of quality control.

I'd guess the plastic is overly thick and needs to be weakened in some way. Knife, drill?

Theo

If this is M20 x 1.5 then a clearance drill of 18.5mm should turn inside the threads.

What's wrong with a hammer and screwdriver on the knockout?

This will leave a 'not knocked out' rim that I suspect will still prevent the cable gland going in.

That did sort of work. I originally tried a hammer with a socket (as in socket spanner) that fitted the hole fairly neatly but that just broke the box. Using a screwdriver did at least punch through without destroying the box, it didn't punch cleanly though, it left several jagged bits of plastic which had to be individually knocked off.

I think I'll steer clear of these boxes from now on!

It says it's ABS but I don't think it is, it doesn't glue with the sort of glue that normally welds ABS.

I have a M20 x 1.25 tap. Necessary if you want to fit conduit to old imperial conduit boxes etc using 3/4" threads.

I'm sure the rim would yield to a cable gland or similar. Or make your own tap using steel conduit with several cuts in the thread to cut new in the plastic.

The other alternative is to drill a 20mm hole and use the nut that comes with the gland for fixing.

Chris Green snipped-for-privacy@isbd.net wrote in news: snipped-for-privacy@q957.zbmc.eu:

In a similar boat<nopun> I used an oscillating multitool to slice the end off from the inside. It was quite neat.

I gave up on cheap boxes and it’s a Wiska box evert time now

OP here, I've ordered a Wiska box and some of their spring clip connectors to connect to the SWA sheath. The Wiska boxes themselves aren't particularly expensive IMHO.

The reviews for this box indicate it has more problems than the non yielding knock out. The cover may not lock and some express the view that it's unlikely to be IP66 compliment due to the sub-standard manufacture.

alan_m snipped-for-privacy@admac.myzen.co.uk> wrote in news: snipped-for-privacy@mid.individual.net:

I don't do a lot of outdoor electrics but I always add a 2mm drain hole in the bottom of any enclosure just in case the waterproofing fails.

Maybe it's thermoset plastic as on their indoor boxes then, and they're lying about it being ABS? ABS you should be able to cut with a blade but thermoset is more likely to shatter.

Another negative point for CED, I bought some light switches and a socket. For the socket, the earth part of the socket bent away from the backplate when a plug was inserted. For a switch, I installed one fresh out of the packet but it didn't click and didn't close the circuit. I took it apart and found the spring mechanism wasn't correctly seated, and had never been correctly installed at the factory. I concluded CED is garbage and junked the rest unopened.

Theo

The trouble with that is that ants can then get in and fill it with earth.

John