BS7671 says refer to MI (Manufacturer’s Instruction) and MI can override BS7671 as it allows for new technologies. However what if the MI is wrong? Do we then need to go back to the document of conformity? Was the conformity done before there was a BS/BSEN standard written?
As always please be polite and respectful in this purely academic debate.
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Selection of the product in the first place is one for the Designer. Hence, if the Designer is worried about conformity, they need to select something else. This is what 'due diligence' is all about.
If the Client forces this on the Designer, there might be some wriggle-room, dependent on the contract, where the Designer can make a statement.
Both of these points are general construction contract law, and/or H&S law (e.g. PUWER), though - not specific to BS 7671 (and nor does it need to be - standards can't take precedence over the law and legislation).
The test report that underpins the DOC will consider the MI's. Often the report will have conditions on approval which are met by specific wording in the test report.
But that report isn't generally put into the public domain - in fact as the test form is typically IECEE copyright the manufacturer couldn't publish it without IECEE permission - which they woudn't get. So yes we have to trust the manufactuer.
If the product has a listing [e.g. UL, TUV, CSA etc.] then it will involve monitoring and re-assessment - and this includes the instructions. But if it's just CE marked [unless there's a notified body] then presume it isn't.
As per 133.5 - If you can produce a robust safety case then you can overide BS 7671. The Scope, Object and Fundamental Principles set out in Part 1 are ultimatly the bit on which the rest of the standard is hung. Overall BS 7671 is not a mandatory standard - but as noted in 114 if you didn't meet BS 7671 then you'd be at a sticy wicket if you found yourself being prosecuted under the Health and Safety at Work Act.
If you had detailed engineering that was properly risk assessed as to why you are deliberatly departing from BS 7671 for a good reason, and noted that report in the departures box on the NIC then you can indeed depart. As an installer you might be installing something innovative which deliberatly departs and which you're advised as such by the manufacturer. Just make sure you note it in the departures box on the IEC. *edit - and obviously only do this if you're satisfied that the departure is underpinned by good engineering advice from a reputable source, not just because the end client has asked you too. Your proefessional and ethical responsibilities must always come first.
Keir Stitt thank you for expanding on the 'due diligence' element.
I've had a few people referring to badly translated MI's as justification. My stock response is to paraphrase my primary school teachers "If the MI's told you do jump of a cliff, would you?".
It's always down to professional judgment - especially if it all goes horribly wrong because at that point you'd need to justify your decision by reference to the paperwork available at the time.
Totally agree if the MI is wrong. Eg a rose and pedant arrangement for an average bathroom dwelling being unsuitable. Engineering judgement needs to be applied.
'taking into account' and 'following blindly' are not the same. I think we have all suffered from translation-ese instructions at some point, and had to stare hard at the sad little pile of bits to work out what they really meant, and then if we really want to do that or something else.
That decision, is the professional judgement that folk pay for of course.
Of course we should refer to the instructions- there may be some essential non-obvious info there - but then use that info with wisdom.
Mike.
BS7671 says refer to MI (Manufacturer’s Instruction) and MI can override BS7671 as it allows for new technologies.
Does BS7671 say that?
133.5 - but you need to note a departure on the EIC.
Often people take this and run a mile with it. According to many lecturers you can use SY cable because the MIs say so - but when you ask them when the last time they saw the MIs for some SY cable their face goes blank.
I'm being unfair to lecturers - the curriculum for the ECS mandates a departure for no good reason.
BS7671 says refer to MI (Manufacturer’s Instruction)
I think it used to say follow MIs - but there was some debate a few years ago along the lines of what if the MIs are clearly stupid/mis-translated/presume some other country's way of doing things - nowadays the wording is "take account of" MIs - which seems to leave a bit more wiggle room for applying a bit of common sense.
- Andy.
I beleive there's two versions of "the regs". One is BS 7671, the other is the in the form of urban legend.
134.1.1 has been on quite an evolution over the years.
I think the extra wording in the seventeenth was introduced with the best of intentions. "proper materials" was a bit meaningless. But if the regs give an inch some people with optimistic readings will take a mile. Nothing in the seventeenth gave you license to do whatever if you can find equipment with MI's to back you up.
Eighteenth wording is more pragmatic. But lots of people still have the seventeeth wording in their head - especially if it's useful to them. The urban legend version of the regs happily borrows from BS 7671 but takes a long time to delete things when they're dropped from BS 7671.
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