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AM2 changes on sources for SELV and PELV

roger Farnsworth

I wonder if anyone here can shed some light on this matter ! - 

 According to BS7671 reg 701.414.3  SELV or PELV supplys in zones 0  / 1 / 2  as described in reg 414.3 (iv) shall not be used  , therefore my question is this , we have previously used IP67 rated 12 / 24 v DC switching mode power supplies to feed colour changing LED downlights in pool areas etc - does the change to BS7671 now make this non compliant ??  and do i now require the extra expense of an isolation transformer ??  I recently asked this question during a seminar on the new AM2 regs , and nobody came up with an answer !?!

Thanks .

  • 0

    You cannot test compliance into a product, it comes from the design. Why we have adopted this standard is ridiculous, is there NO ONE left who can actually read proposed standards and see that they are useful, and in compliance with all the existing ones? I am currently working on another problem, but the same kind of thing has happened, NO ONE has actually understood what is in a draft!

  • 0

    My assumption was that normal lighting 'transformers' (including electronic ones) would provide isolation according (i) or (ii) - and that (iv) was only for some weird and wonderful contraptions that didn't provide conventional isolation from the mains (the note talks about test equipment).

    Looking at a couple of data sheets though I can't see BS EN 61558 obviously mentioned though - maybe it's implied via more specific product standards or may be I'm being overly optimistic...

       - Andy.

  • 0

    It all depends on how those SMPSUs are made.

    This has been complicated by the fact that a new standard BS EN 62368-1, which has now replaced BS EN 60950-1, does not recognise SELV and PELV especially the behaviour under single-fault conditions. The alternative provisions do not fully align with BS EN 61140 requirements for SELV and PELV. The second consideration, is that not all electronic equipment standards recognise the need to maintain the lowered SELV/PELV voltages in certain Part 7 locations, including under single fault conditions.

    Now, what's really confusing is that a particular product may meet the requirements for SELV and PELV (and even the lower voltage requirements), but there is now no way to prove that by complying with certain (but not all) product standards (some other product standards cross-refer to BS EN 62368-1).

    Sadly, the onus is on the installer to check the product meets the requirements (of BS 7671), but of course some of these devices are "plug and play" and a consumer may well get hold of their own (non-compliant) replacement.

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