Replacement Hob Question of Available KW Load

[ban-all-sheds]

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

But is it?

You are assuming that your concept of what it means must be correct, and that therefore it must be grammatically wrong and therefore must not be read as written.

Is it?

That make no sense as an answer to

"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?"​

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

I'm not saying I was wrong. From memory I thought you were in the camp of those who would rather do anything except use the simplest and most direct reading of the regulations because they were simply not prepared to let go of a long-standing previous belief that the regulations said something other than what they did. My memory, of course, may be faulty.

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

Maybe your long-standing previous belief is wrong.

Why do so many people think that the tongue has zones of receptors for sweet, salty, bitter etc?
Why do so many people think that "You can't have your cake and eat it" makes any sense?
Why do so many people think that Marie Antoinette said "Let them eat cake"?
How do you know you're not simply wrong because so many people before you were wrong? Remember this?:

I often quote a story I was told about 50 years ago by my Chemistry teacher. He drew our attention to an alleged chemical reaction which had first been 'described' in a 'trusted' textbook around 1900. By the 1960s, that reaction was described in virtually every chemistry textbook in existence, including the most respected and 'authoritative' ones. The only problem is that, at some point in the 60s, it was discovered that the reaction in question didn't actually happen, and never could have happened in the past! Sheep follow sheep!

 

[JohnW2]

... 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?......

 

[ban-all-sheds]

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?

I'm not sure how you reach that conclusion, whichever way you interpret the guidance.

Each appliance is either

10 + 0.3 x (10 - 10) = 10 (i.e. the 1st 10A + 30% of the remainder)

or

10 (i.e. 10A + 30 % of the flc of {an appliance in excess of 10A})

or

10 + 0.3 x 10 = 13 (i.e. 10A + 30 % of the flc)

There are no inter-appliance diversity guidelines in the OSG, so you'd just have to add those up, giving you 60A or 78A.


One problem here is that when the guidelines first went into the OSG, this is what a domestic cooking appliance looked like:

but they have changed a bit.....

Maybe the guidance is no longer appropriate.

If your "half a dozen 10A domestic cooking appliances" were welded together into a 6 plate hob, you'd end up with one single 60A appliance and 25 or 28A, which feeds into the idea I've often proposed which is that it makes no sense to consider, say, 2 built-in ovens and a hob as 3 appliances, each with their own 10A + whatever, because there are no electrical or usage-pattern factors which mean that if you took an angle grinder to a range cooker and split it into 3 lumps you'd suddenly be using more electricity, or conversely if you took your 3 appliances and installed them into a single free-standing cabinet with one external facing electrical connection you'd suddenly be using less.

But however you slice and dice your half-dozen, I can't see how you could get them all onto a 10A circuit.

 

[AndyPRK]

slow day ban? to drag up a 3 month old thread?

 

[JohnW2]

slow day ban? to drag up a 3 month old thread?

It certainly looks that way

Kind Regards, John

 

[ban-all-sheds]

Says the man who dragged it up in a PM to me only a few days ago....

 

[JohnW2]

Says the man who dragged it up in a PM to me only a few days ago....

Only because, as a matter of courtesy, I recently got around to replying to a 3-month old PM to me (the purpose of which was to inform me that the author no longer had access to the thread - a situation which has clearly now changed)

 

[ban-all-sheds]

It has.

Either such locks are time-limited, or the Mods came to their senses and realised that they couldn't justify the action they took.

 

[JohnW2]

Since this discussion seems to have been resurrected ...

That's the way that English works.
10A + 30% f.l. of {connected cooking appliances in excess of 10A}....

As has been said, that surely cannot possibly be the intention, since, as has been said, it would mean that the after-diversity current of a single appliance with a f.l. of 10.1A would be 13.03A - which is clearly ridiculous, Hence, even if the above is a grammatically correct interpretation of what has actually been written, it clearly cannot have been what they intended their words to mean.

I am less sure how it is being suggested that the above interpretation would be applied to the situation of multiple appliances. If, for example, there were six cooking appliances, each with an f.l. of 10.1A, the above 'formula' would produce a result of 28.18A - but what has one then calculated, the after-diversity current of one of the appliances (which would be ridiculous) or the after-diversity current of all six of them (which would be 25.18A if calculated 'conventionally')?

 

[ban-all-sheds]

As has been said, that surely cannot possibly be the intention, since, as has been said, it would mean that the after-diversity current of a single appliance with a f.l. of 10.1A would be 13.03A - which is clearly ridiculous, Hence, even if the above is a grammatically correct interpretation of what has actually been written, it clearly cannot have been what they intended their words to mean.

Maybe because the guidance was written to apply to cookers, not 10A cooking appliances.

What, for example, is an electric steamer or a sous-vide cooker? Are they cooking appliances, and thus potential candidates for diversity, or are they thermostatically controlled water heaters?

Maybe neither of those existed (the second one certainly didn't) when the guidance was written.

I am less sure how it is being suggested that the above interpretation would be applied to the situation of multiple appliances.

Maybe because the guidance for "Individual household installations including individual dwellings of a block" was never expected to be applicable to an installation with 6 cooking appliances.

 

[JohnW2]

Maybe neither of those existed (the second one certainly didn't) when the guidance was written. ... Maybe because the guidance for "Individual household installations including individual dwellings of a block" was never expected to be applicable to an installation with 6 cooking appliances.

Yes, they are both credible 'explanations'.
However, I'm not sure that it's all much of a problem in practice. Many of the more modern appliances are clearly 'standalone' things, which will often have 13A plugs and for which diversity is not really an issue (or appropriate), since they would not normally be 'sharing a supply' with other cooking appliances in the way in which we are usually considering. However, as for ovens, grills and hobs etc., all connected to a single supply, I don't think it unreasonable to think of them as if they were all 'welded together' to create a single 'cooking appliance', with diversity applied to the totality of it all, even if they were physically separate.