Workshop RCD, Radial circuit

[JohnW2]

If a circuit is defined as a "Final circuit" (A circuit connected directly to current - using equipment, or to a socket-outlet or socket-outlets or other outlet points for the connection of such equipment.) then how can it feed any other circuit? It is like saying very end. Clearly very is not required as end is the end. Final is in the same way the last circuit you can't have the very final circuit in same way as can't have very end or very last.

I agree with what you say about the semantics, but that doesn't really help us with the sort of issues/questions arise (primarily relating to 'notifiability').

It's all very well saying that 'a final circuit' is 'final' but what then happens if one then extends it to feed additional loads via a further OPD(s) (FCU, MCB in a CU or whatever). Does that first circuit now cease to be a 'final circuit'? If so, what do you now call it - as far as the downstream OPD is concerned, I suppose you could call it a 'submain' - but that would make very little sense if it were primarily a circuit supplying, say, a number of sockets.

As has been extensively discussed, probably the greatest problem in attempting to define 'a circuit' (hence 'a new circuit') is finding a definition that does not result in an FCU creating a 'new circuit'.

Kind Regards, John

 

[ban-all-sheds]

That's obviously the problem. If one sticks precisely to the BS7671 definition of a circuit, then I don't think there's any escaping the fact that anything 'new' downstream of an FCU would be a 'new circuit', and hence notifiable. I don't think that (m)any of us believe that was 'intended' - let's face it, even prior to the 'relaxations' in April, extending circuits with fused spurs was explicitly non-notifiable.

Yes - I've pointed that out, and asked why they didn't just word the amendment to make any installation of a CU, new or replacement, notifiable if that was what they wanted.


For good measure I've also asked why such work, in fact any work, has never been notifiable in Schedule 2 exempt buildings. One of those could quite legitimately contain a bath or shower room - the only thing it may not have is sleeping accommodation, but because it's a detached single storey building, having a floor area which does not exceed 30m2, which contains no sleeping accommodation and is a building—
(a) no point of which is less than one metre from the boundary of its curtilage; or
(b) which is constructed substantially of non-combustible material,

you don't need approval to do anything in it which you would need if it were, for example, 5.1m x 6m instead of 5 x 6.

 

[ban-all-sheds]

As has been extensively discussed, probably the greatest problem in attempting to define 'a circuit' (hence 'a new circuit') is finding a definition that does not result in an FCU creating a 'new circuit'.

Also, the definition of "circuit" in BS 7671 includes "final circuit", so changing a circuit, either to or from being a final one, does not create a new one, and it's "new circuit" which is of significance in the Building Regulations, not "new or modified circuit".

 

[ericmark]

My son could rewire his narrow boat without having to notify even though there is a lot more water around than in any bathroom and it included a bathroom. Same applies with a caravan. Due to size and use his narrow boat did not come under RCD either.

Note RCD = recreational craft directive.

Part P has never made sense why do you think that will change.

 

[JohnW2]

That's obviously the problem. If one sticks precisely to the BS7671 definition of a circuit, then I don't think there's any escaping the fact that anything 'new' downstream of an FCU would be a 'new circuit', and hence notifiable. I don't think that (m)any of us believe that was 'intended' - let's face it, even prior to the 'relaxations' in April, extending circuits with fused spurs was explicitly non-notifiable.

Yes - I've pointed that out, and asked why they didn't just word the amendment to make any installation of a CU, new or replacement, notifiable if that was what they wanted.

Good question. However, even if they had done (just) that, it would be far from watertight. Firstly, at the level of pedanticism (which is what matters with law!), we all know that it's very easy to have something which looks like, smells like, sounds like and functions like 'a CU' which does not fulfil the BS7671 definition of a Consumer Unit - so they would need to try to plug that hole (again, hopefully without 'catching' FCUs).

In any event, even if they could make that fairly 'watertight' (but sparing FCUs) that would still leave the possibility that people could 'emulate' a CU in a garage/shed etc. with an RCD and two or three FCUs

For good measure I've also asked why such work, in fact any work, has never been notifiable in Schedule 2 exempt buildings. ... you don't need approval to do anything in it which you would need if it were, for example, 5.1m x 6m instead of 5 x 6.

We've been through this before, and I'm a bit confused (maybe just forgetfull!). What makes all electrical works in such exempt buildings non-notifiable? As we've established before, whilst exempt buildings (per Schedule 2) are generally exempt from all building regs, 9(3) of the regs specifically makes Part P applicable to exempt buildings of Class 6 & 7. Is there something somewhere else which says that, although subject to Part P, no electrical works in such exempt buildings are notifiable?

Kind Regards, John

 

[JohnW2]

Part P has never made sense why do you think that will change.

I would say that Part P makes total sense (as far as it goes) and that no-one should have any problem with it. It's the rules about notification that have never made sense, probably because far too little thought went into (a) what they really wanted to achieve, (b) what potential 'loopholes' or anomolies they had to deal with, and (c) what wording they should use to make a legally 'watertight' statement of that 'intent'.

Kind Regards, John

 

[brunoo]

Who De-railed my thread?

All went well with the installation.

Obv the RCD is earthed through the mains cable, But is it worth adding a seperate earth to a radiator near the RCD? Or is it not needed.

Kind regards

 

[ban-all-sheds]

Obv the RCD is earthed through the mains cable,

Obviously?

That's not an RCD, it's a voltage operated earth leakage circuit breaker.

It is old, obsolete and unsafe - it must be replaced.

 

[JohnW2]

Obv the RCD is earthed through the mains cable,

Obviously? That's not an RCD, it's a voltage operated earth leakage circuit breaker. It is old, obsolete and unsafe - it must be replaced.

I seriously doubt that such is what he was attempting to refer to - it would make little sense in terms of the rest of what we've been told (particularly in the OP).

Kind Regards, John.

 

[EFLImpudence]

But is it worth adding a seperate earth to a radiator near the RCD? Or is it not needed.

It's not possible to tell from here.

If in a bathroom etc. measurements need to be taken to determine whether the radiator pipes are extraneous and so may require bonding to other parts of the installation (to equalise potential in the event of a fault).

Radiators never require earthing (to ensure automatic disconnection should they become live).

If not in a bathroom etc., then no.

 

[JohnW2]

But is it worth adding a seperate earth to a radiator near the RCD? Or is it not needed.

It's not possible to tell from here.

You say that, but ...

If in a bathroom etc. ... If not in a bathroom etc., then no.

Does that not mean that, even 'from here', in the case of the OP's workshop (which presumably does not qualify as a bathroom etc.), the answer is 'No' (which is what I would have said)?

Kind Regards, John

 

[EFLImpudence]

I forgot is was a workshop.

Now he'll tell us he does have a bath in there.

 

[ban-all-sheds]

I seriously doubt that such is what he was attempting to refer to - it would make little sense in terms of the rest of what we've been told (particularly in the OP).

Brunoo - what is it you've looked at, which you think is an RCD, and have seen an earth connection to it?


And why...

The shower is on a 40A RCD in the main CU with 6MM T&E direct to the shower, I will be disconnecting this and using a 2-way 100A junction box, Then continuing with 6mm T&E to the workshop RCD unit.

Why have 2 RCDs in series?

 

[JohnW2]

I seriously doubt that such is what he was attempting to refer to - it would make little sense in terms of the rest of what we've been told (particularly in the OP).

Brunoo - what is it you've looked at, which you think is an RCD, and have seen an earth connection to it?

I frankly doubt that he was 'looking at' anything. I suspect that he has limited understanding of how these things work and thought that a circuit somehow gets an earth connection through its RCD (or MCB) - or, perhaps more likely, he was meaning that the earth connection was coming from 'the RCD unit' (which is how he's decribing the secondary CU).

And why...

The shower is on a 40A RCD in the main CU with 6MM T&E direct to the shower, I will be disconnecting this and using a 2-way 100A junction box, Then continuing with 6mm T&E to the workshop RCD unit.

Why have 2 RCDs in series?

If you read the OP, you'll see that he has used 'RCD' to refer to what almost ceratinly are MCBs. He speaks of a "40A RCD" (ex shower cct) in the main CU supplying "6A and 32A RCDs" in the 'Garage CU' he's using for the workshop, All we do know for sure (from the Screwfix link) is that this 'Garage CU' does, indeed, contain an RCD. Although the 'main CU' may be RCD protected, I don't think we've been told anything to confirm that (since I believe his reference to a 40A RCD supplying the old shower circuit in fact relates to an MCB).

Kind Regards, John

 

[ban-all-sheds]

I wonder what, in his mind, makes him think he is anywhere near competent to be installing CUs?