Cable entry into Consumer unit

[Taylortwocities]

Yes, but not Eaton/MEM. And the lighting busbars are on the unprotected busbar direct from the main switch.
Would be worth seeing a pic of the whole thing. Even better to see inside.

 

[Jupiter01]

Yes, but not Eaton/MEM. And the lighting busbars are on the unprotected busbar direct from the main switch.
Would be worth seeing a pic of the whole thing. Even better to see inside.

Here you go

 

[JohnW2]

That is exactly how my Square D was designed:

What you describe/illustrate appears to be one of the variants of how a 'high integrity' CU can be configured. However, if that's what the OP has, it would still presumably be the case that, as TTC suggested, the two lighting circuits would be without RCD protection.

Kind Regards, John

 

[SUNRAY]

What you describe/illustrate appears to be one of the variants of how a 'high integrity' CU can be configured. However, if that's what the OP has, it would still presumably be the case that, as TTC suggested, the two lighting circuits would be without RCD protection.

Kind Regards, John

Yes but let's not forget lighting circuits were amongst the last to require RCD protection, no idea of correct date.

Those boards were being fitted in Bush House refit, BBC left in 2012 so as recently as 2013/14.

 

[plugwash]

I'm pretty sure it was the 17th edition that introduced the RCD protection requirements for concealed cables, that in practice required most domestic circuits to be RCD protected.

Some time later (think it may have been the 18th edition) they introduced a specific requirement for RCD protection of domestic lighting circuits, but it was largely academic, most domestic lighting circuits would have required RCD protection already under the concealed cables rules.

Bush house seems to be an office building, if it was wired in conduit/trunking as seems to be quite common in office buildings then afaict even today there would be no need for RCD protection on it's lighting circuits.

 

[JohnW2]

Yes but let's not forget lighting circuits were amongst the last to require RCD protection, no idea of correct date.

I think that started with the initial version of 18th, in 2018. However, as plugwash has observed, the requirement for RCD protection of buried cables (almost inevitable in any lighting installation, given switches) was earlier than that.

However, I think what we are probably all agreed about is that, unless it was installed by a total clown, that CU was installed an awful lot more than 4 years ago - so who knows what regs applied at the time?!

Kind Regards, John

 

[Jupiter01]

Well, there could theoretically be two RCDs if both were connected to the main switch by cables (as in a 'high integrity' CU), rather than one being connected via a little busbar - but, as you imply, only an idiot would "do it like that"

Kind Regards, John

Presumably this would require three separate neutral bars?

 

[Jupiter01]

Is an RCD a two pole switch?

 

[EFLImpudence]

Is an RCD a two pole switch?

An RCCB is; an RCBO is not - except double pole ones which you won't have..

RCCBs and RCBOs are RCDs

 

[Jupiter01]

An RCCB is; an RCBO is not - except double pole ones which you won't have..

RCCBs and RCBOs are RCDs

What do we have in this picture?

 

[EFLImpudence]

That is an RCCB - a Residual Current Circuit Breaker - which is an RCD - a Residual Current Device - as are RCBOs - a Residual Current Circuit Breaker with Overload protection.

 

[Taylortwocities]

30mA double pole RCD

 

[EFLImpudence]

30mA double pole RCD

but it's not an RCBO.

 

[Jupiter01]

I’ve seen some garage CU’s that only have an RCD (and some MCB’s). There’s no main switch.
In that situation, the RCD is ostensibly the main switch?

 

[JohnW2]

Presumably this would require three separate neutral bars?

Indeed - and that's what 'high integrity' CUs have. There has to be a neutral bar for circuits protected by each RCD and a neutral bar for circuits not protected by any RCD - so, yes, if there are two RCDs and also some non-RCD (maybe individually RCBO-protected circuits, then there needs to be three neutral bars (which, as said, is what 'high integrity' CUs have.

Kind Regards, John