BS7671:2008(2015) - Cmin=0.95 and no other obvious surprises

JohnW2 · 7 Jan 2015

OK, speculation is over. At first glance, I can see no difference between Amd3 (as now published as the BYB) and what was in the DPC.

In particular, as rather expected, the value of "Cmin" remains as 0.95, despite the suggestion from myself and others that, in view of range of permitted UK supply voltages, 0.94 would perhaps be more logical. However, it may not be 'their fault'- it seems that the value of "Cmin" is probably defined by "PD CLC/TR 50480", whatever that may be. This means, for example, that the oft-quoted 'maximum Zs' of 1.44Ω for a circuit protected by a B32 MCB nas now fallen to 1.37Ω, and that for a circuit protected by a B50 has fallen to 0.87Ω.

I'll be looking in more detail but, as above, at first glance I don't think there are any surprises in the BYB. For example, as expected, all references to 'competent persons' have been removed (replaced with "skilled or instructed person"), and the requirement to comply with MIs has been relaxed.

Kind Regards, John

pompeygit · 7 Jan 2015

So it's £75 for trivial changes that could have easily been incorporated in an 18th edition with game changing amendments. It's becoming tiresome having to up date your library so often for minutia. But I guess as the salaries of the movers and shakers of our industry increase exponentially they must grab every revenue stream they can.

pompeygit · 7 Jan 2015

So it's £75 for trivial changes that could have easily been incorporated in an 18th edition with game changing amendments. It's becoming tiresome having to up date your library so often for minutia. But I guess as the salaries of the movers and shakers of our industry increase exponentially they must grab every revenue stream they can.

Spark123 · 7 Jan 2015

You can say that again

JohnW2 · 7 Jan 2015

pompeygit said:
So it's £75 for trivial changes that could have easily been incorporated in an 18th edition with game changing amendments. It's becoming tiresome having to up date your library so often for minutia. But I guess as the salaries of the movers and shakers of our industry increase exponentially they must grab every revenue stream they can.

That's certainly one view, but I suspect that if there weren't these Amendments, then new editions would come out a lot more frequently, so it probably wouldn't make a lot of difference. The average interval between editions (with intervening amendments) over recent decades has been about 13 years. On that basis, the 18th is not due until about 2021 - but I very much doubt they would have left it anything like that long if there were not intervening Amendments.

Of course, if these were goverment-imposed/legislated regulations, we probably would not have to pay to have access to them.

Kind Regards, John

Spark123 · 7 Jan 2015

The last amendment wasn't available as an amendment document, we had to buy the lot again. They may as well have stuck a new number on the front cover.
I'm not sure if amendment 3 is available as a stick in document for my green reg book. I've managed to forget my username and password for the IET site

JohnW2 · 7 Jan 2015

Spark123 said:
The last amendment wasn't available as an amendment document, we had to buy the lot again. They may as well have stuck a new number on the front cover.

When you say 'the last amendment' do you actually mean Amendment 1 (2011)? Most of us never heard of, or saw, Amendment 2, which I believe was a standalone new chapter relating to electric vehicle charging.

Spark123 said:
I'm not sure if amendment 3 is available as a stick in document for my green reg book. I've managed to forget my username and password for the IET site

I would rather doubt it - not the least because the introduction of the concept of Cmin has resulted to extensive changes to tabulations (and text) involving, or related to, Zs throughout the document. For the same reason, the new OSG due to be published at the end of the month will contain 'numerous changes'.

Kind Regards, John

Spark123 · 7 Jan 2015

Yep, amd 1 that had us all buying the green books a couple of years back.
I think the last time the IET published an amendment on its own was the blue to brown 16th edn.

JohnW2 · 7 Jan 2015

Spark123 said:
Yep, amd 1 that had us all buying the green books a couple of years back.

Indeed it did.

Spark123 said:
I think the last time the IET published an amendment on its own was the blue to brown 16th edn.

Yes, I think that's right. However, as I said, even if it were still the usual practice, I'm not sure that it would really be all that practical/useful to publish Amd 3 as just an amendment.

Kind Regards, John

ban-all-sheds · 8 Jan 2015

Well it would be if they abandoned their rapacious pricing for electronic versions.

JohnW2 · 8 Jan 2015

ban-all-sheds said:
Well it would be if they abandoned their rapacious pricing for electronic versions.

With an electronic version, there's really no point/need to publish separate 'amendment' documents, such as Spark123 was discussing - one might as well just have amendED electronic versions.

The pricing (of either paper or electronic versions) is a separate issue!

Kind Regards, John

ban-all-sheds · 8 Jan 2015

I must admit I don't understand his point - AFAIR the price of Brown 16th Amended was no different to what it would have been had they made it Brown 17th.

JohnW2 · 8 Jan 2015

ban-all-sheds said:
I must admit I don't understand his point - AFAIR the price of Brown 16th Amended was no different to what it would have been had they made it Brown 17th.

I presume that he's talking about the difference between a small 'amendment document' (just a list of the changes), rather than a full amended version of the entire book.

Kind Regards, John

ban-all-sheds · 8 Jan 2015

Can't be done unless it's a tiny (probably error-correcting) amendment that could be pasted in, or unless they were to reintroduce the loose-leaf ring binder hard copy version when they could realistically publish changed pages.

JohnW2 · 8 Jan 2015

ban-all-sheds said:
Can't be done unless it's a tiny (probably error-correcting) amendment that could be pasted in, or unless they were to reintroduce the loose-leaf ring binder hard copy version when they could realistically publish changed pages.

Indeed. As I've been saying, certainly in the case of the extensive changes (involving very many pages) in the recently published Amd3, it would be totally impractical to do anything other than publish a full, amended version.

Kind Regards, John

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