Fitting consumer unit vertically

[JohnW2]

Fair enough - consider that you have a single installation. OOI, which part(s) of it could be regarded as 3-phase?

530.3.4 says nothing about any parts of the installation being single-phase or not - that reg applies to installations that have a "single-phase supply". If we are considering that I just have one installation, then I don't really see how one can say that that the supply to that one installation is "single-phase", largely because it isn't!

Do you also consider that the small block of flats has a single installation?

Not really. However, as I said, I would suspect that a lot of people (probably including myself) would probably regard everything electrical within a single dwelling as being 'the (one) electrical installation'. In a block of flats, each flat would be a separate single dwelling, in the same way that my house is a single dwelling.

Kind Regards, John

 

[ban-all-sheds]

530.3.4 says nothing about any parts of the installation being single-phase or not - that reg applies to installations that have a "single-phase supply". If we are considering that I just have one installation, then I don't really see how one can say that that the supply to that one installation is "single-phase", largely because it isn't!

It may not have a single, single-phase supply.

But with no 3-phase circuits, no 3-phase loads and no 3-phase devices I do not see how it can by any stretch of the imagination be termed a 3-phase installation. But I do see how it can very easily be termed multiple single-phase ones, and I don't feel the need for any gyrations about what the regulations intend. In fact, if you consider the talk of "≤100A" and "under the control of ordinary people" I think it far more likely that they intend your house to have 3 single-phase installations, not 1 3-phase one.

Not really. However, as I said, I would suspect that a lot of people (probably including myself) would probably regard everything electrical within a single dwelling as being 'the (one) electrical installation'. In a block of flats, each flat would be a separate single dwelling, in the same way that my house is a single dwelling.

If the landlord were to knock two flats into one, but make no changes to the electrics, you're saying that there would then be 5 installations. So in the new Flat 1, would that be a 2-phase installation?

This has much in common with the discussion on Gatso time and space.

Basically, if you propose a defining rule which does not work, i.e. it does not create a determination free of ambiguities, with no dependencies on any "well it depends" etc, then your rule is a false one, and you have to discard it and find one which does work.

 

[JohnW2]

But with no 3-phase circuits, no 3-phase loads and no 3-phase devices I do not see how it can by any stretch of the imagination be termed a 3-phase installation.

530.3.4 says nothing about "X-phase installations" (Where X is some number other than 1). It talks about "an installation" with a "single-phase supply".

It's very kind of you to go to all these lengths to try to convince me that my CUs (without 16kA) are actually compliant, but the regs are so unclear that I cannot know whether you are right or not.

Kind Regards, John

 

[ban-all-sheds]

530.3.4 says nothing about "X-phase installations" (Where X is some number other than 1). It talks about "an installation" with a "single-phase supply".

Of which you have 3.

How would you categorise the situation (which I'm sure has been reported on this forum) of a premises where there's a 3-P cable coming in, there are 3 cutouts, but only one phase is used and there is only one single-phase meter and one single-phase CU? Is that an installation with a single-phase supply?

It's very kind of you to go to all these lengths to try to convince me that my CUs (without 16kA) are actually compliant, but the regs are so unclear that I cannot know whether you are right or not.

The only way I can be wrong is if one CU and its final circuits are not an assembly of associated electrical equipment having co-ordinated characteristics to fulfil specific purposes.

 

[John D v2.0]

How would you categorise the situation (which I'm sure has been reported on this forum) of a premises where there's a 3-P cable coming in, there are 3 cutouts, but only one phase is used and there is only one single-phase meter and one single-phase CU?

Yes that's me at least,

PS neither of you, and no one else is going to learn anything new, so might be worth calling it quits then everyone's a winner

 

[ban-all-sheds]

So have you got a single-phase installation, or not?

 

[JohnW2]

Yes that's me at least,...

I don't think that one really presents any problems. Since only one of the phases which enters the building is connected to anything, I can't see that anyone would dream of describing what goes on electrically in the place (whether one calls it an 'installation' or whatever) as anything other than single-phase.

PS neither of you, and no one else is going to learn anything new, so might be worth calling it quits then everyone's a winner

I have certainly learnt something new. Until BAS recently raised the issue, it had never occurred to me that the 'electrical setup' (I can't really use that other word!) in my house might, strictly speaking, be extensively non-compliant (with BS7671) - and whether or not that is the case depends on the definition of "installation". I have a total of something like 50 'devices' in CUs/DBs around the house, none of which (I think) are 16kA rated.

However, as you say, there's not much more to discuss, since we can but speculate about the thing that matters (to me) - i.e. the meaning of BS7671's definition of an 'installation'. Although I've started a Poll, which I suspect (in some senses 'unfortunately) may end up showing a picture which differs from BAS's view, that will only be a matter of 'opinions'.

Kind Regards, John

 

[ban-all-sheds]

I don't think that one really presents any problems. Since only one of the phases which enters the building is connected to anything, I can't see that anyone would dream of describing what goes on electrically in the place (whether one calls it an 'installation' or whatever) as anything other than single-phase.

If a 2nd CU, supplied by one of two currently unused phases, were to be installed, how would that change what goes on electrically within what was already there?

 

[JohnW2]

If a 2nd CU, supplied by one of two currently unused phases, were to be installed, how would that change what goes on electrically within what was already there?

It obviously wouldn't, but it would change the 'supply' to the totality of the electrical setup (what else can I call it?!) within the premises into something that was not a 'single-phase' supply.

Kind Regards, John

 

[EFLImpudence]

It obviously wouldn't, but it would change the 'supply' to the totality of the electrical setup (what else can I call it?!) within the premises into something that was not a 'single-phase' supply.

Why?

It would alter the installation but it wouldn't change the supply to your premises/installation.

 

[JohnW2]

Why? It would alter the installation but it wouldn't change the supply to your premises/installation.

It would functionally. If only one phase is connected to anything (and, I presume, the other two don't even have fuses in the cutout), I would call it a single-phase supply, wouldn't you? The 'supply' is surely that which is made available to the consumer, regardless of what is inside the DNO's box?

If you think the supply hadn't changed, are you suggesting that it had been 3-phase all along or single-phase all along?

Kind Regards, John

 

[EFLImpudence]

Surely, if the three cut-outs are in your premises then the supply must be three phase.
That is what the DNO supplied.

That you don't use two of them does not alter that.

 

[JohnW2]

Surely, if the three cut-outs are in your premises then the supply must be three phase. That is what the DNO supplied. That you don't use two of them does not alter that.

I don't know. As I said, I would interpret 'supply' as what had been available for the consumer's use. If, as I suspect is likely, two of the phases don't have service fuses, I would not say that the DNO had 'supplied' those phases.

However, that's obviously different from my situation, since I am using all three phases. Do I take it that (despite BAS's view) you agree with what I have always assumed - that I have one installation with a 3-phase supply?

Kind Regards, John

 

[EFLImpudence]

I don't know. As I said, I would interpret 'supply' as what had been available for the consumer's use. If, as I suspect is likely, two of the phases don't have service fuses, I would not say that the DNO had 'supplied' those phases.

The supply is there should you require it.

However, that's obviously different from my situation, since I am using all three phases. Do I take it that (despite BAS's view) you agree with what I have always assumed - that I have one installation with a 3-phase supply?

I do agree.

However, can that include sub-installations and/or sub-supplies to various parts?

 

[JohnW2]

The supply is there should you require it.

Is it? I could not make use of it without action on the part of the DNO, so I'm not sure that it could be said that I were currently 'being supplied' with it.

However, there is one matter we have not considered, which might be important to this discussion - namely that of contracts. I presume that I must somewhere have a dusty contact from my supplier, and I imagine that will indicate what supply (1-phase, 3-phase or whatever) they have contracted to supply?.

I do agree. However, can that include sub-installations and/or sub-supplies to various parts?

Goodness only knows. The BS7671 definition of 'installation' is vague enough, so what they would regard as a 'sub-installation', I haven't a clue - and they don't define 'supply', let alone 'sub-supply'! In any event, the crucial 530.3.4 refers only to 'installation' and 'supply', not to sub-anything!

Kind Regards, John