Double slot RCBO's

[Eric1066]

Hi,

Let me start with the following info:

1. I live in Cyprus which has 230v 50hz system.

2. Cyprus uses UK style everything. The regs may be slightly different here, but by and large they follow the UK. They use ring circuits for sockets, loops for lighting and they are going to change soon to metal cases for the units, just like in the UK. (Anecdotal examples)

I've just installed a small consumer unit in a shed. Main switch, 1x32a for a double socket and 1x6a for the lights. I asked for MCB's but was told to use RCBO's instead.

Ok.

Because of my curiosity, I went online to find out what RCBO's are, what's the difference etc... and EVERY video I watched had 1 slot RCBO's, with a neutral tail and a cream coloured 'functional' earth tail...

What I was sold was 2 slot RCBO's with L&N screws on top and L&N screws at the bottom and NO tails. Also a busbar that had 2 tracks. One for the Neutral and one for the Live. Ok, i figured it out, was pretty simple, installed and it all works...

There's no 'functional' earth tail though... i can't see where I would make an earth connection to these RCBO's... why do the UK RCBO's have this? Why don't these 2 slot ones have it? Is this less desireable?

Pics attached.

Any help would be greatly appreciated!!

 

[binky]

Not all RCBOs have a 'tail'. The earlier ones had earth leads, most now have neutral leads, but yours doesn't need a lead as it has direct connection to the neutral bus bar.

 

[kerching]

My complete house is covered by double pole RCBOs, my choice as I think it's a better installation. Others may have a different opinion, which is wrong
In my opinion DP RCBOs should have been mandated in the areas. In many ways UK leads the world in electrical installation, but some elements are lacking. DP RCBOs being one of them

 

[Badger]

We also have rcbo protection not dual rcd board any where to be seen here

 

[MikeJhn]

What I was sold was 2 slot RCBO's with L&N screws on top and L&N screws at the bottom and NO tails. Also a busbar that had 2 tracks. One for the Neutral and one for the Live. Ok, i figured it out, was pretty simple, installed and it all works...

What you have been sold is a EU standard RCBO and not the antiquated RCBO's that UK wholesalers are still selling, yours should have the L&N in at the top also available staggered to use dual bus bars and feed out from below.

 

[Eric1066]

Thank you guys, so much. Mind at ease!!
I really appreciate all the replies!!

 

[MikeJhn]

My complete house is covered by double pole RCBOs, my choice as I think it's a better installation. Others may have a different opinion, which is wrong
In my opinion DP RCBOs should have been mandated in the areas. In many ways UK leads the world in electrical installation, but some elements are lacking. DP RCBOs being one of them

Uk Electricians seem to be scared of increasing the size of the CU which is inevitable when using duel slot RCBO's eventually we may get to the EU standards which dictate CU positions within a domestic property and maximum amount of sockets on any one circuit, lots of other sensible rules as well, but all increase the rows and size of the CU.

 

[Eric1066]

Oh! Well my house here has THREE CU's, 2 on the ground floor and one upstairs... I thought this was mad, as in the UK, no house I ever had, had more than 1, even if it was massive.

So having three is a good thing?

 

[MikeJhn]

IMO yes, when a circuit trips out its only the circuit that it controls, therefore easier to find a fault if one exists, if you have incandescent lights this can trip a MCB if the bulb blows so only the bulb needs replacing in most case's.

 

[binky]

Oh! Well my house here has THREE CU's, 2 on the ground floor and one upstairs... I thought this was mad, as in the UK, no house I ever had, had more than 1, even if it was massive.

So having three is a good thing?

You don't see it these days, but I've encountered old houses with socket and lighting circuits per room. All radials of course.

 

[Eric1066]

You don't see it these days, but I've encountered old houses with socket and lighting circuits per room. All radials of course.

With regard to that... i always heard that the reason we have ring circuits is to save on copper.. I don't get it, unless I really dont understand radial circuits. My understanding is, from the breaker you run a line into the room connect a socket, continue to another socket and when you get to the last socket.. it ends there.

I've just put a CU into a shed, a 32A RCBO for the ring... of 2 double sockets. Surely a radial circuit is better and far less copper in that instance, but I just did what I know.

 

[binky]

With regard to that... i always heard that the reason we have ring circuits is to save on copper.. I don't get it, unless I really dont understand radial circuits. My understanding is, from the breaker you run a line into the room connect a socket, continue to another socket and when you get to the last socket.. it ends there.

I've just put a CU into a shed, a 32A RCBO for the ring... of 2 double sockets. Surely a radial circuit is better and far less copper in that instance, but I just did what I know.

It was ages ago when copper shot up in price. So much so they even started using aluminium cables. I don't run rings these days unless I really need the higher ampage it offers. As for your shed, I would have used 20A and radial cct, it's not compulsory to fit sockets to a ring.
,

 

[kerching]

Not run a ring main( domestic) for years , no need, use radials.
Run MV rings but that's a different kettle of lobsters.
Regarding DP RCBOs, all mine are single slot so the same size as an MCb. Fair enough, I do have an 18way board though

 

[MikeJhn]

I will see your 18 way board and raise you my 52

 

[MikeJhn]

Regarding DP RCBOs, all mine are single slot so the same size as an MCb. Fair enough, I do have an 18way board though

As far as I understand these things a single module RCBO with fly lead is not really a dual pole, the neutral is dragged along with the live when it trips as it does not have the solenoid connected to it, happy to be put right.

I don't like the fly lead single modules and use dual pole dual module RCBO's in preference, no common neutral bar, far easier to test and no spurious trips from cross connections.

 

[kerching]

https://www.sbstradesales.co.uk/assets/datasheets/e6bfba69cc2c380fbf47c03324cb4feafd000038.pdf

 

[MikeJhn]

Thanks for that, not seen them before.

 

[Sharpend]

https://www.sbstradesales.co.uk/assets/datasheets/e6bfba69cc2c380fbf47c03324cb4feafd000038.pdf

Oh I have a house with those

 

[Eric1066]

Just a quick question, as I've got all you guys attention

Just going through some of the stuff I jave here and noticed something, if you can shed some light on it for me.

I have 2 dp rcbo's by 2 different manufacturers. One has the neutral to the right screw, the other has the neutral on the left screw... pic attached. This means i couldn't use a dual busbar if I want all of these connected next to eachother due to space limitation in the case, OR is it not a problem wiring these things either way around and the N stamp is merely a suggestion?

I know I can simply turn it upside down, and make the connection that way, but my OCD won't let me.

 

[MikeJhn]

https://www.sbstradesales.co.uk/assets/datasheets/e6bfba69cc2c380fbf47c03324cb4feafd000038.pdf

Shame they do not show a internal circuit diagram to see if the neutral is short circuit activated or just dragged along with the phase.