buying a house

[EFLImpudence]

Why are guidelines a nonsense?

Where did I say that? They might not be. This one is.

As above, arbitrarily increased by 7.64% from 92.9 to 100m² (solely because of bureaucracy) with no regard for the consequences.



What possible relevance can the floor area have with regard to a circuit?

 

[JohnW2]

The floor areas are mentioned in the OSG, but are also mentioned in Appx 15. .... It says compliance with 433.1.103 can be achieved by, amongst other things, taking account of the floor area served. (Historically, a limit of 100m² has been adopted).

Indeed it does. However, I would say that that "taking account of" calls for some judgement and common sense - 100m² of kitchens, utility rooms and workshops etc. is obviously very different from 100m² of bedrooms, store rooms, bathrooms etc.

... and, of course, just like the OSG, Appendix 15 is only 'guidance'.

Kind Regards, John

 

[securespark]

Where did I say that?

More O.S.G. nonsense?

What possible relevance can the floor area have with regard to a circuit?

Cable length?

 

[JohnW2]

What possible relevance can the floor area have with regard to a circuit?

It's obviously an attempt to take account of the likely loads. It's a pretty poor attempt, but I'm not sure what would be better. One can estimate the likely loads for a given occupier at a particular point in time, but the need is to consider what might happen in the future, maybe with different occupants.

I would say that, at least, it's better than 'number of sockets'. In some rooms, some people might want umpteen sockets 'for convenience' (so there is always going to be one close to where one is needed), without any intention of ever using more than a tiny proportion of them at any one time.

Kind Regards, John

 

[JohnW2]

Cable length?

Cable length is cable length, and that is explicitly covered by actual regulations (regarding Zs and VD), rather than mere 'guidelines'.

A 5m² room distant from the CU/DB could involve a longer cable run than a circuit supplying 100m² close to the CU/DB

Kind Regards, John

 

[EFLImpudence]

Cable length?

Not really a result of the area, is it?
Why not specify a maximum length (for those incapable of working it out)?


Bugger, my flat is 101m²; I can't have a ring circuit.

 

[EFLImpudence]

It's obviously an attempt to take account of the likely loads.

I can't see how.

It just (as you implied) states a maximum area with no mention of the actual design.

 

[securespark]

I don't see anything in Appx 15 advising it is guidance only and not forming part of the regs. It says "(Informative)". Does that mean it is not part of the regulations?

Definition of informative: Serving to inform; providing or disclosing information; instructive.

 

[securespark]

Not really a result of the area, is it?

It can be.

Bugger, my flat is 101m²; I can't have a ring circuit.

Good, cos rings aren't in Portugal's wiring code.

 

[JohnW2]

I can't see how. It just (as you implied) states a maximum area with no mention of the actual design.

Sure but, as I said, given no crystal balls, one cannot make any informed judgement as to actual electricity usage of a certain bit of space in the future, one has to (even if only subconsciously) make some guesstimate, and "the amount of the house covered" (aka floor area) is one of the factors that one would considerer, isn't it?

Kind Regards, John

 

[JohnW2]

I don't see anything in Appx 15 advising it is guidance only and not forming part of the regs. It says "(Informative)". Does that mean it is not part of the regulations?

Yep. In this sort of context, "informative" means that it is just guidance (not a 'requirement'), as opposed to 'normative', which means that it is a 'requirement'. Look on p296 of the BYB and you will find ...

Appendix 1 is normative, and is thus a requirement. All other appendices are informative, and are provided as guidance.

Kind Regards, John

 

[EFLImpudence]

Did whoever pretended to think about this originally and wrote the regulation (it beggars belief that it actually was a regulation) have in mind that the maximum length of a ring is approximately 100m. and that is the perimiter of a 10m. x 10m. square (Edit - no it's not, silly me, it's only 40m. so makes even less sense.) (stupidly ignoring any meandering of the cable) or that it may be on the third floor, involving another 12m. for height.

Also, not realising that the building (e.g. Victorian terraced) may be 20m. x 5m. with only a 50m. perimiter.

It really is ridiculous.

 

[securespark]

Missed that!

 

[JohnW2]

Did whoever pretended to think about this originally and wrote the regulation (it beggars belief that it actually was a regulation) have in mind that the maximum length of a ring is approximately 100m. and that is the perimiter of a 10m. x 10m. square (stupidly ignoring any meandering of the cable) or that it may be on the third floor, involving another 12m. for height. .... It really is ridiculous.

As I said, I think that they probably 'did their best' to think of something which vaguely related to the likely electric load.

I think we can probably all agree that the decision is best left to the judgement of the (hopefully intelligent and sensible) designer, but regulations don't like doing that - and, indeed, some designers are more comfortable 'being told' than having to think for themselves (if they are capable of doing that) - not the least because they regard 'being told' as better from a 'CYA' viewpoint!

Kind Regards, John

 

[Risteard]

I don't see anything in Appx 15 advising it is guidance only and not forming part of the regs. It says "(Informative)". Does that mean it is not part of the regulations?

Definition of informative: Serving to inform; providing or disclosing information; instructive.

Yes - Informative clearly means it is not part of the Regulations. Even BS7671 points this out.

Also: the Informative Appendix makes it clear that this was a "historical" requirement - this clearly indicates that it is absolutely NOT a requirement anymore. That's what "historically" means.