Replacement Hob Question of Available KW Load

[EFLImpudence]

 

[EFLImpudence]

Go to 3.20

 

[src1]

Really?




Yes, a socket for a plug.

Not a socket for the head of a bolt.

Or a socket for the end of a ball on a bone.



I really am so looking forward to the fun that will ensue when you try to claim that you really had no idea that he meant something like this:

Please don't wait too long, as I need to get to bed.

Yes this is it, we have one of these mounted close to each appliance. Each appliance is hard wired and isnt connected by a plug to this.

All I must say a thankyou for the constant support

 

[ban-all-sheds]

OSG (and the other two books cited): 10A + 30% f.l. of connected cooking appliances in excess of 10A....

Note it does not say 10A + 30% f.l. in excess of 10A of connected cooking appliances...

The "in excess of 10A" is an adjectival phrase which, because of its position, relates to the cooking appliance, not the full load current.

It means that the current is deemed to be 10A, plus, if the appliance has a f.l. current of over 10A, 30% of that f.l. current.

That's the way that English works.

10A + 30% f.l. of {connected cooking appliances in excess of 10A}....


As for the link to the book on TLC's site, you can either go with what 3 IET books say when read according to the rules of English, or you can decide to ignore those things because you want to believe someone else who read it wrongly.

But it is only a guideline.

 

[ban-all-sheds]

Go to 3.20

Go to 3:58

 

[DetlefSchmitz]

So according to BAS.
For a 10A cooker you have to allow 10A.
For an 11A cooker you have to allow 13.3A.
Ah, that's what diversity means then.

 

[JohnW2]

The standard wording is .... the first 10A plus 30% of the remainder.

What's going on? I am relying on the formula which has been in existance for 60 years.

I've been silently watching these exchanges with interest - since I also wondered "What is going on?". Like you, in all the years I've known about diversity for domestic cooking appliances, everyone I've known has regarded/interpreted it as "the first 10A plus 30% of the rest" - and, incidentally, that has been the basis of innumerable posts in this forum over the years, without anyone ever having previously challenged it.

Given that, as far as I know, there are no regulations which cover this, I'm not sure who/what could be regarded as an authoritative determinant of what the formula 'should be' - but I think/presume that nearly everyone relies upon the OSG.

I initially thought that BAS's most recent (grammatical) comment simply related to poor wording by people who didn't understand the grammatical nuances. However, now having looked at my (red) OSG, I'm starting to wonder. Whilst the wording for domestic cooking appliances is as has been stated, for small shops etc. and small hotels etc. is it stated as "100% of f.l. for first appliance and X% of f.l. for second appliance and Y% of f.l. of remaining appliances - so they do, in some situations, use that grammatical construct. However, for the generic/default domestic "Heating and Power (but see 5 to 8 below)", it says "100% of total demand up to 10A plus 50% of any current demand in excess of 10A" - which is consistent in form with how we have all always understood the calculation for domestic cooking appliances.

If BAS's ('grammatically strictly correct') interpretation correctly reflects the 'intention', it is surely crazy - since it means that one could have an unlimited number of 10A (or lower) appliances on one circuit with the 'after diversity' current of the lot never being more than 10A. Indeed, if one regarded all the 'hob rings' and ovens as being separate appliances (after all, they could theoretically be physically separate) one could end up concluding that a massive cooker (or, certainly, the equivalent in 'separates'), with many hob 'rings' and several small ovens/grills, could be run off a B10 with 1.5mm² cable! The interpretation which nearly all of us have always used seems a lot more sensible than that.

Kind Regards, John

 

[EFLImpudence]

What then is the difference between Tables A1 and A2?

Mr.Ward did not seem to notice the difference.

As Detlef has pointed out, 11, 12, or 13A ovens, by Table A2, are therefore not allowed on 13A plugs.

This is obviously wrong so the first column of Table A2 must be an error - hard to believe such a thing is possible in the OSG.

 

[ban-all-sheds]

What then is the difference between Tables A1 and A2?

Mr.Ward did not seem to notice the difference.

So is he one of the many who cannot or will not read properly?

As Detlef has pointed out, 11, 12, or 13A ovens, by Table A2, are therefore not allowed on 13A plugs.

Using diversity calculations is not compulsory.

This is obviously wrong so the first column of Table A2 must be an error - hard to believe such a thing is possible in the OSG.

Or the 5th row of A1 is wrong.

 

[EFLImpudence]

So is he one of the many who cannot or will not read properly?

Irrelevant. Which is correct?

By the other two links and indisputable logic -

As Detlef has pointed out, 11, 12, or 13A ovens, by Table A2, are therefore not allowed on 13A plugs.
This is obviously wrong so the first column of Table A2 must be an error - hard to believe such a thing is possible in the OSG.

it must be A1

Using diversity calculations is not compulsory.

Again irrelevant.
When using it, a method that makes sense is probably the correct one.
Occam's razor.

Or the 5th row of A1 is wrong.

Unlikely as the equivalent of A2 is a nonsense.
Occam's razor.

 

[DetlefSchmitz]

So pick one: (aimed at BAS if any doubt)
1) The method as you understand it is correct although it results in wildly illogical results
2) The use of English by the author(s) does not match your high standards.

 

[ban-all-sheds]

When using it, a method that makes sense is probably the correct one.

But not a parsing of the sentence according to the rules for the language it's written in?

Occam's razor.

Which is a "lesser" assumption?

That a formula designed for typical domestic cooking appliances doesn't work with atypical ones, or that we have to use special grammar when reading it?

Occam's razor.

From memory not a philosophical concept which had much traction with you regarding HIE ring finals....

 

[EFLImpudence]

But not a parsing of the sentence according to the rules for the language it's written in?

Again irelevant if that sentence is grammatically correct but conceptually wrong.

Which is a "lesser" assumption?

Is it?

That a formula designed for typical domestic cooking appliances doesn't work with atypical ones, or that we have to use special grammar when reading it?

Unless the concept of the statement is incorrect.

From memory not a philosophical concept which had much traction with you regarding HIE ring finals....

From memory, I thought I agreed with you on that, or are you saying you were wrong?


Are you saying that we should alter our long-standing previous belief because one of two contradicting statements disagrees with it?

 

[DetlefSchmitz]

But not a parsing of the sentence according to the rules for the language it's written in?

Usually whenever an 'engineer' tries to express a mathematical formula in words, the result will be ambiguous. That is why we have mathematical formulae.

Frankly I think you should stop digging.

 

[JohnW2]

Per what Detlef recently wrote (and also what I previously wrote), and just to get this clear in my mind ...

... am I correct in my understanding that is it being said that the 'correct' interpretation of the OSG is the one which leads unavoidably to the conclusion that it is permissible/appropriate to run, say, half a dozen 10A domestic cooking appliances from a circuit wired in 1.5mm² cable and protected by a B10?

If so, common sense seems to be conspicuously absent from one of the views being expressed in this thread.

Kind Regards, John