CU cable entry

[tabbypurr]

How to get 4 cables into this CU?

Metal CU has clearances of: top 4" bottom 4" right: 0 left: plenty, but the tails run up there.

A christmas-tree cone bit is at least 2" long, leaving little space for a drill for top or bottom. Right is possible by drilling through what it's up against, but the result would look lousy. Left there's enough space in theory, but a lot of hand held drilling with a large bit very close to tails? Not loving that idea. Looked at cutting into the front edge rather than using round entry glands, but not seeing fireproof grommet strip anywhere.

Suggestions welcome!

[alan_m]

Q max punch?

Example

or

[alan_m]

Smaller hole still required to fit punch but could that be done by drilling from inside of the box?

[spuorgelgoog]

Photo please :-)

Can you unfix it from the wall and pull it forward?

Owain

[tabbypurr]

Interesting. Last time I used those, long ago, they severely distorted the sheet they were punching. Is there some way to avoid that?

NT

[Andy Burns]

armeg holesaw, doesn't need separate arbor so shorter (use with right angle drill if possible)

[Brian Gaff (Sofa 2)]

Have you ever spent longer getting the bit you punched out of the cutting tool than cutting the hole in the first place? Grin. Brian

[alan_m]

I've used them in the past without problems but are you sure that it was the punch causing the distortion or you applying a sideways force to the whole punch assembly and twisting the metal.

You can get a Q-MAX Thrust Race to make winding in the punch much easier and possibly help with with any unwanted forces you apply to the structure you are working on

Google "Q-MAX Thrust Race"

[nothanks]

Aren't there any knock-outs to, errr, knock-out? If not, you could get a nibbler into a 4" gap and then improvise grommet strip from anything suitable (saw blade protector, slit sleeving, T&E outer ...) and then use high-temp silicone to form a seal. I have a hand nibbler and also one that goes onto a drill, for this job I'd use the latter. Mine is one of these:

but bought 10-15 years ago and much used for sheet metal work.

[Dave Plowman (News)]

A Q-Max cutter. Needs very little clearance once you have the pilot hole. And gives a perfect hole.

[alan_m]

I usually have that problem with hole saws into wood

[tabbypurr]

the metal was in free air, and the punch tightened with spanners. The problem is that the punch cutting edge is not flat, so as it pushes 2 parts of the potential hole, the whole sheet wanted to follow it & get very bent. I know punches sometimes work, but IMLE with them you need a lot of surrounding metal to resist that urge to bend horribly.

sure, not sure it's worth it for 1 or 2 holes.

NT

[tabbypurr]

It looks like there are, but I can only conclude they weren't pressed deep enough, as the whole box starts to bend under great force before those bits show any interest in moving.

Interesting.

NT

[tabbypurr]

Is that 18th edition passable?

[nothanks]

I can't give a categorical "yes", but also can't see why not. The cable is protected from the metal edge by the improvised grommet strip and the hole is sealed and fireproof. Hmm, I typed "high-temp silicone", but I meant "fire-retardant silicone"

- like this

[ARW]

The absolute best.

Did I show you them at ELEX or did you already know about them? I cannot remember.

Also they do not fly through the hole you have just cut as they have a wider diameter base than the hole you have cut.

Both CK and Starrett now have similar (first links I could find)

Its worth noting that they fit impact drivers (the Armeg one does) which are usually smaller than a cordless drill if space is tight.

Usually when cutting into a DB or trunking full of cables I use the floorboard lifter as protection against against the hole cutter causing any damage.

[Andy Burns]

Yes, you did ...

cheaper too.

[Dave Plowman (News)]

Get some decent quality ones? If the tolerances are poor, it won't shear accurately.

[Tricky Dicky]

It might be easier to simply pull the CU off the wall, this of course means pulling the DNOs service fuse but will also give you the opportunity to fit a separate isolator switch. I would not worry about anybody Complaining about it, I did it and when the guy came to fit the smart meter he said nothing and resealed the fuse afterwards as well as the isolator switch.

Richard

[tabbypurr]

The ones I was using were the Qmax you recommended.