32mm Holesaw in Metal Consumer Unit knock out - balls up!

[Noob2013]

Hi all,

I was dreading drilling a 32mm hole in the top of a Hager metal Consumer Unit for a 25mm Swa. There are square knock outs all along the top and my worse fear was the knock out coming out.

Anyway, there is limited room so I had no choice but to terminate the swa in the consumer unit.

I started drilling the hole and all was fine until the very last bit - the knock out came out!

So I now have one of the square knock outs in the top of a hager board missing with a half circular hole.

Possible due to lack of experience but how can I gland the swa now?

I was thinking I could have a square piece of metal either side of the costumer unit with a 32mm hole in each to fix it securely.

Any ideas much appreciate

 

[Octopus]

I don't have an answer but have been pondering this one too!

Shame the CU manufacturers don't have answers and more shame to the IET for implementing such a stupid reg

 

[midgetman]

Terminate into a metal box first which is up against the hole and feed cable through there. Feel for ya lol

 

[Octopus]

The OP did say he had limited space!

 

[midgetman]

Oh yes lol

 

[Leesparkykent]

Bolt a plate over the top and re-drill hole.

 

[Barrie Patrick]

I think, if possible I'd take a jig saw to the top of the CU and take out or put as big a slot in the top as I could and then plate it with some metal sheet, maybe cutting something like a piece of trunking or adaptable box lid. then terminate the armoured into it and possibly slot the rest for any sheathed cables. Just be careful you get rid of sharp edges, grommet strip or maybe piece of Truflex? and make it look as good as you can? Barrie

 

[Noob2013]

Cheers for the advice.

I think I'll try the idea me and Leesparkykent had with use a piece of metal.

I just had a thought, the large oval knock outs I took out for rear cable entry are big enough and will look better as they are the same colour and finish as the consumer unit

 

[Octopus]

The CU manufacturers need to start selling "blank" kits!

 

[malcolmsanford]

Plate is the only realistic way forward now.

But in future when drilling something like this put a piece of 9.5/12.5 mm plywood under it held in place with a c clamp. Should stop the knockouts from falling out

 

[7029 dave]

Have not fitted CU for long time, why the hell are knockouts square.? square terminations these days.? lol

 

[Dizzy_Maskell]

For me make a new plate and pre drill this so fits nicely over balls up and your glans holds it all together !

 

[topquark]

Yep, plate it (and maybe put some high temp sealant around it).

Won't help here but the newer Contactum boards have 32mm knockouts on both sides (top right side and top left side) and also on the bottom right and top right. Not a recommendation as I don't like the fit of the front, but for future ref.

 

[Englishman]

Not any help now, but you could possibly drill a smaller hole and then open it up with one of those cone cutter things, designed to open metal holes up.

 

[Richard Burns]

Have not fitted CU for long time, why the hell are knockouts square.? square terminations these days.? lol

For mini trunking entry of cables, perhaps?

For me make a new plate and pre drill this so fits nicely over balls up and your glans holds it all together !

An interesting turn of phrase you have there ! mg_smile:

 

[Sintra]

Bolt a metal besa box lid on and re-drill.

 

[Ryan Scott]

You could get your grinder and cut a slot out of the top of the CU and stick a bit of 3 or 4 inch trunking on top of that depending if you have many cables coming into it

 

[NDG Elecs]

Not any help now, but you could possibly drill a smaller hole and then open it up with one of those cone cutter things, designed to open metal holes up.

Not a bad idea at all. I wander whether the knock out would still hold firm though. Malcolm's idea should allow for the hole to be drilled neatly. Silly design by the manufacturers, they should have a couple of different options for the actual enclosure. Maybe they should do a bit of market research, asking sparks their views..

 

[Englishman]

May hold but may not. The horrible "knock outs" on the back of the Crabtree Starbreaker would hold though, they just refuse to ever come out.

 

[HandySparks]

For me make a new plate and pre drill this so fits nicely over balls up and your glans holds it all together !

...An interesting turn of phrase you have there ! mg_smile:

Indeed, I was about to make the same comment. :biggrin5:

A sketch of the final assembly could cause offence!

 

[Redvanman]

Doesn't help your situation but in future get the Hagar boards that have no knock outs if you are going to drill it out.
They do make both

 

[PEG]

I have had this occur,when knock-outs displace,or errors,retro-fit etc,necessitates a change of position or aperture size.

Usually,it is best to fit as large a piece of material as is possible,which matches the original cabinet. This can make any "special" shapes or slots,easier to machine,as it can be vice-work.

A few years back,i had cause to strip out several phone mast control cabins,which possessed a myriad of enclosures,cabinets and racking.

The stores area had a large pile of packaged,stainless blanks,epoxy coated on one side,and in varying size,from 50mm square,to 100 mm x 500 mm.

These have proved invaluable for such tasks,fixed suitably to maintain continuity.

When drilling around such knock-outs,you have to be ready for when they fall out...with only a "knock" :stooge_moe:

 

[overskilled]

For me make a new plate and pre drill this so fits nicely over balls up and your glans holds it all together !

don't think he or the customer will be very happy with the end of his penis holding a CU together!!

 

[Geordie Spark]

Not any help now, but you could possibly drill a smaller hole and then open it up with one of those cone cutter things, designed to open metal holes up.

This could be useful:https://www.cef.co.uk/catalogue/products/1039967-20-36mm-titanium-coated-step-drill

 

[davesparks]

This could be useful:https://www.cef.co.uk/catalogue/products/1039967-20-36mm-titanium-coated-step-drill

Apart from being made by silverline and sold by CEF it looks lovely

 

[Geordie Spark]

Apart from being made by silverline and sold by CEF it looks lovely

Yes I know! BUT it shows that they are available up to & beyond 32mm ....... I thought the biggest was 22mm.

That said, it's not something that you use all day everyday so for the occasional use it could ok PROVIDED you keep the speed (RPMs) down & use plenty of lubricant.


And there's always this:

 

[malcolmsanford]

Yes I know! BUT it shows that they are available up to & beyond 32mm ....... I thought the biggest was 22mm.

That said, it's not something that you use all day everyday so for the occasional use it could ok PROVIDED you keep the speed (RPMs) down & use plenty of lubricant.


And there's always this:

Ohhhhhhh now we are talking. Great for making holes in stainless

 

[Marvo]

I don't think you should be drilling the knock-out smaller than its intended diameter in the first place, you should either remove it entirely or not use it at all. Problem is if you drill it and fit an SWA gland there's a good chance it's going to break free anyway at some time in the future. The CU manufacturers should stop catering to DIY'ers and fit a proper gland plate that doesn't have pre-perforated knock-outs or leave the side and back walls without knock-outs assuming they're strong enough to take SWA glands without distorting.

 

[Octopus]

I don't think you should be drilling the knock-out smaller than its intended diameter in the first place, you should either remove it entirely or not use it at all. Problem is if you drill it and fit an SWA gland there's a good chance it's going to break free anyway at some time in the future. The CU manufacturers should stop catering to DIY'ers and fit a proper gland plate that doesn't have pre-perforated knock-outs or leave the side and back walls without knock-outs assuming they're strong enough to take SWA glands without distorting.

Problem is Marvo that there are countless existing installations where changing the CU is made difficult by all the DIY changes and hence why, I suspect, they have these large knock outs - quite how they expect the installer to maintain the IP rating and the "non combustibility" is questionable.

 

[Geordie Spark]

Ohhhhhhh now we are talking. Great for making holes in stainless

And the beauty of it is it's operated by hand so there's no fear of a numpty spark who has no comprehension of Speeds & Feeds (basic engineering stuff) ever burning it out!!! :laugh: