Square D MCB to RCBO

Marcus Vaughan · Nov 8, 2018

Hi All,

I have just been to to view a job on my way home. The customer is asking for a new double socket immediately below the consumer unit (that's convenient!).

It's an old Square D board without an RCD in sight.

I guess it would be very easy to install an RCD socket outlet - spurring from either the kitchen ring or 'main ring' one way or the other.

But I was thinking - probably for the same price - I could swap out the MCB for an RCBO, though it would be second hand, but with the obvious benefit of providing additional protection for an entire socket circuit.

I thought of suggesting a board change - but that seems a bit OTT when a customer on a budget only wants an additional socket.

Question is then - what would you do?

Perhaps its not viable anyway - the MCB's are marked up as Dom, eg Dom32B6 - so am searching the web to see if a replacement RCBO even exists (by Square D/Schneider)...........

Octopus · Nov 8, 2018

Spur from CU, surface trunking, RCD socket ......... only if earthing and bonding in place

As of the 1st Jan 2019 ............... these issues will get far , far more difficult..

Marcus Vaughan · Nov 8, 2018

Murdoch said:
Spur from CU, surface trunking, RCD socket ......... only if earthing and bonding in place

Thankyou.

ipf · Nov 8, 2018

Agree with that. Difficult to find anything suitable, RCBO wise.
I like that 'useful' little drawing on the lid, by the way.
If it keeps tripping, keep resetting, maybe?

123 · Nov 8, 2018

You can get RCBO's for that board. Like here. I'm not sure if Schneider make new ones for it, not familiar with that range, usually just see the older QOE (eyewatering prices for RCBO's) and the KQE stuff here.

Octopus · Nov 8, 2018

MK seem to fit nicely .............

KEV 1 N · Nov 8, 2018

I think this replaced the DOM...Easy 9 by Schneider

Marcus Vaughan · Nov 8, 2018

123 said:
You can get RCBO's for that board. Like here. I'm not sure if Schneider make new ones for it, not familiar with that range, usually just see the older QOE (eyewatering prices for RCBO's) and the KQE stuff here.

Good spot that.

To prove I am doing my homework though - I found this https://www.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/content/live/FAQS/175000/FA175169/en_US/Easy9_Domae conversion.pdf

from Schneider.

which suggests to me that a new easy 9 RCBO will fit straight in?

Kev 1 - we must have typing at the same time!
I think you are right though.

Marcus Vaughan · Nov 8, 2018

Murdoch said:
MK seem to fit nicely .............

I didn't take the cover off - but at least the cover itself hasn't been butchered. That's the third CU I've seen today with mixed MCBs.

KEV 1 N · Nov 8, 2018

Beware the old KQE RCBO and DOM are made opposite to each other....in terms of fitting to the bus bar.

It is possible to remove the clip on the KQE type to give a normal screw terminal (we often did it when fitting into old Merlin Gerin boards) however the new Schneider type you can’t remove the clip as they’re glued in place!

Octopus · Nov 8, 2018

Marcus Vaughan said:
I didn't take the cover off - but at least the cover itself hasn't been butchered. That's the third CU I've seen today with mixed MCBs.

Its extremely common .........

ChrisElectrical88 · Nov 8, 2018

KEV 1 N said:
Beware the old KQE RCBO and DOM are made opposite to each other....in terms of fitting to the bus bar.
View attachment 45585
It is possible to remove the clip on the KQE type to give a normal screw terminal (we often did it when fitting into old Merlin Gerin boards) however the new Schneider type you can’t remove the clip as they’re glued in place!

Drill the glue out and the screw is just behind it. Did it almost every week at one of my last companys. Didnt effect the RCBO at all.

westward10 · Nov 8, 2018

That consumer unit is not that old Domae was aimed at the domestic market to replace the Quickline II.

Marcus Vaughan · Nov 8, 2018

westward10 said:
That consumer unit is not that old Domae was aimed at the domestic market to replace the Quickline II.

That’s interesting. I have worked on a quick line boards - so these came after...

I think I’ll dead test one of those ring finals, and if all OK, fit an easy9 RCBO and incorporate the new socket into the ring. I’d have a warm glowy feeling if I left a whole circuit RCD protected. I don’t think the materials would cost significantly more anyway.