MSF100 Switch fuses and amended regs
- Thread starter m109254
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Indeed, and I think that change is what has introduced some confusion into our minds, and into this discussion. One has to wonder whether the change was 'deliberate' (the references to the OSG and "IEE Guidelines" have also now gone).
Kind Regards, John
I think you'll find that 511 is referring to standards other than itself.
I think you'll find that the wording re non-combustible switchgear is insufficiently detailed and rigorous for it to be a standard which could guide manufacturers and test houses in the manufacturing and testing of products.
I think you'll find that "BS 7671 compliance" is not something which can be claimed of, or applied to, switchgear.
And I think you'll find that everybody knows that you already knew all of that.
Yes, I suppose you're right.
However, let's consider: we know that BS7671 requires CUs to be non-combustible. We know that is not possible, so as you have previously pointed out we have to assume that what is meant is something like "sufficiently non-combustible". We also have an example - ferrous metal - of what is considered to be sufficiently non-combustible.
So, if someone were to use a CU that was acceptable in another country's national standard, given that 511 requires the designer to confirm that the level of safety is not lower than that for a UK product, would he not have to demonstrate that his CU was at least as "non-combustible" as a ferrous metal one in order to claim conformity of his design to BS7671?
However, let's consider: we know that BS7671 requires CUs to be non-combustible. We know that is not possible, so as you have previously pointed out we have to assume that what is meant is something like "sufficiently non-combustible". We also have an example - ferrous metal - of what is considered to be sufficiently non-combustible.
So, if someone were to use a CU that was acceptable in another country's national standard, given that 511 requires the designer to confirm that the level of safety is not lower than that for a UK product, would he not have to demonstrate that his CU was at least as "non-combustible" as a ferrous metal one in order to claim conformity of his design to BS7671?
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Well - you tell us.
You are the one with all the experience of standards.
Would "manufactured from non-combustible material" in a standard applying to the construction of consumer units etc, with no definition of "non-combustible", no description of tests to demonstrate conformance etc, be acceptable?
Do you think that people should have to imagine the presence of words not in a standard in order to understand what it means, or to make it workable?
You say "confirm that the level of safety is not lower than that for a UK product", but there are no relevant standards which apply to UK products.
Oh - and BTW - as soon as you start arguing that what they really meant to require was "sufficiently non-combustible" then you immediately allow the use of consumer units which are considered sufficiently non-combustible in a large number of advanced countries, and also considered sufficiently non-combustible to be used in this country in places of work, public entertainment, schools, hospitals, childrens' homes, old people's homes....
The list goes on and on, and encompasses buildings occupied by vulnerable, dependent people. If a CU is considered sufficiently non-combustible to be used there, care to explain how it would not be safe to use in a house if "sufficiently non-combustible" was the criterion?
You are the one with all the experience of standards.
Would "manufactured from non-combustible material" in a standard applying to the construction of consumer units etc, with no definition of "non-combustible", no description of tests to demonstrate conformance etc, be acceptable?
Do you think that people should have to imagine the presence of words not in a standard in order to understand what it means, or to make it workable?
You say "confirm that the level of safety is not lower than that for a UK product", but there are no relevant standards which apply to UK products.
Oh - and BTW - as soon as you start arguing that what they really meant to require was "sufficiently non-combustible" then you immediately allow the use of consumer units which are considered sufficiently non-combustible in a large number of advanced countries, and also considered sufficiently non-combustible to be used in this country in places of work, public entertainment, schools, hospitals, childrens' homes, old people's homes....
The list goes on and on, and encompasses buildings occupied by vulnerable, dependent people. If a CU is considered sufficiently non-combustible to be used there, care to explain how it would not be safe to use in a house if "sufficiently non-combustible" was the criterion?
Not necessarily, I would say. Although BS7671 mentions ferrous metal as an example material which it regards as being "sufficiently non-combustible" (which, as I've said before, sounds like an oxymoron!), it does not say that it is the "least non-combustible" (!!) that would be acceptable. In other words, despite that one example given, it does not say that a material which was "more combustible" than ferrous metal (whatever that means) would necessarily not be acceptable. There simply is not enough information.
It is, in my opinion, simply a very poorly thought-through and written regulation. One could say that it is analogous to the situation which would exist if Standards specified that insulating materials (in cables, enclosures etc.) had to be "non-conducting". Again, the presumed intent would be "sufficiently non-conducting" (again an oxymoron) - but, again, without further clarification (i.e. specified tests) it would be meaningless and uninterpretable.
Kind Regards, John
No, it wouldn't.
No, they shouldn't.
Yes there is - BS EN 61439-3. However products to that standard are not considered adequate by BS7671.
If BS7671 were to be submitted as a draft IEC standard then no doubt the "non-combustible" requirement as well as several others would have to be improved.
However, notwithstanding all the above, we are where we are, and in the absence of clarity we have to try to interpret the requirements as best we can. A consensus that a steel enclosure is necessary for compliance with BS7671 seems to have developed, and I am merely trying to point out that compliance with another country's installation standard would possibly not be sufficient.
Although you have highlighted the word "not", does the "possibly" not also deserve highlighting? - i.e. through lack of information/detail in BS7671, we simply don't know?
Kind Regards, John
Perhaps, but we also don't know what is in the hypothetical "other country's standard" that might be considered a breach of UK requirements. I rather suspect that the author(s) of the earlier AD P had assumed that installation regulations were the subject of Harmonised Standards.
Indeed not - but that's primarily because we don't know (other than for one example) what the "UK requirements" actually are!
Kind Regards, John
My point was that even where the UK requirements are clear, we cannot know if those requirements are met by some other unspecified standard.
Well, it's only a finite number other other (known) standards.
However, my point is that, notwithstanding what you say, if the UK requirements are not clear (which is the situation we're discussing) we cannot even start to think about whether those (unclear) requirements would be satisfied by compliance with some other standard.
Kind Regards, John
Yes, sorry, I'd forgotten what the OP was about!
It's actually what the entire 4 pages of discussion have been about, not just the OPYes, sorry, I'd forgotten what the OP was about!
Kind Regards, John
Most of it, yes.
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