Nick, A very informative piece on the MD, but as regards the LVD people may think that there WILL be a much revised LVD and it will look a lot like the consultation which the Commission ran last year. As far as I am informed, however, the Commission are still totting up the results of their consultation. Therefore, it is by no means certain that the final outcome will be a revised LVD with many more detailed essential requirements (certainly, many trade organisations, such as ORGALIME, are opposed to the radical change proposed). Time, as they say, will tell.
I don't think that LVD product standards cross-referencing other standards is anything new. For instance, product standards for equipment have always cross-referenced component standards for things like cables and connectors. Perhaps there are now a few more cross-referenced standards, but only a few. Like any good law, the LVD has been able to adapt to changes in societal expectations and technological development: in the cases you cite this has happened by embracing requirements for EMF and accepting the fact that more and more products contain LEDs (the requirements for LED products currently being in IEC/EN 60825-1 - though that is set to change). Because ICT equipment has incorporated lasers for many years IEC 60950-1, and before that IEC 60950, and before that IEC 950, and before that IEC 335, cross-referred to IEC 60825-1 and its forerunners (i.e., no change in principle). If the essential requirements (strictly called the 'safety objectives' in the LVD) were more proscriptive, then this ability to move with the times would be diminished - thereby forcing the LVD to be updated more often. Once the revised MD, as now finally agreed by the European Parliament, becomes effective by transposition in national law, it will be interesting how the change in the way it overlaps with the LVD will be addressed. The proscriptive list approach in the revised MD would seem to replace one set of problems (for which answers by now should already have been found) with another (for which answers will need to be found). Looks like the need for informed consultancy on this issue will be around for a few more years! Regards, Richard Hughes Nick Williams wrote: > I hear the argument you are making, John, but with the benefit of > about ten years of experience dealing with the Machinery Directive > I'm rather more positive about its approach. Since I believe the > approach which the new LVD will take (when it finally get enacted) > will be modelled on the Machinery Directive, I think it's worth > spending a little time looking at this in more detail. > > What the LVD does at present is it says "Here's a set of VERY basic > safety objectives and here's a list of standards. If you apply these > standards, you will (probably) meet the very basic safety objectives, > and at very least you will have some evidence that you tried to meet > the safety objectives even if you are ultimately found to have > failed. Either way, you will be able to CE mark your product and sell > it anywhere in Europe without having to meet any additional rules". > > What the Machinery Directive says is "Here's a detailed list of basic > safety objectives. You HAVE to meet these except where they patently > do not apply to your machine. If you want a yard stick against which > to measure whether or not you have meet the safety objectives which > apply to your machine, here's a list of standards you can use. Some > of these standards are general, some of them are specific, but they > all support one or more of the basic safety objectives of the > Directive. If you use them you will (probably) meet the basic safety > objectives, and at very least you will have some evidence that you > tried to meet the safety objectives even if you are ultimately found > to have failed. Either way, you will be able to CE mark your product > and sell it anywhere in Europe without having to meet any additional > rules". > > Superficially the approaches look very similar, but they are subtly > different and, so far as the standards are concerned, the differences > are immense. > > LVD standards are essentially comprehensive. In general, you need > only apply one standard and it covers all of the hazards associated > with a piece of equipment (OK, so where a standard has a General and > a Particular requirement, you need two documents, but in theory at > least they come together to make a single standard). > > Machinery standards are very different. The most important ones are > called 'type B' standards and usually cover only one aspect of a > machine's design. For example, EN 418 deals with emergency stops, EN > 1037 tells you how to ensure energy sources are isolated, EN 999 > tells you how to use light guards, EN 982 gives rules for the use of > hydraulics, etc etc. There are maybe 100 or 200 of these 'type B' > standards. Some machines will have only a few which apply, others > will have many, but they are all oriented around providing guidance > on the design of a particular aspect of machinery in general, rather > than dealing the the overall design of a specific type of machinery. > > There are also hundreds of standards (so called 'type C' standards) > which deal with specific types of machinery. For example, EN 693 > deals with hydraulic power presses, EN 1494 deals with vehicle jacks > and EN 201 is the standard for injection moulding machines. These > standards contain lots of specific requirements for the types of > machinery which they cover, but they also contain a lot of references > to the 'type B' standards, and they may say things like "clause > 1.2.3.4 of EN 123 does not apply to horizontal light curtains used on > power presses with closing speed of less than 30mm/second". There are > no type C standards which are self contained - i.e. which can be used > without any reference to the type B standards. > > So, whenever one applies standards in support of the Machinery > Directive, one is always going to have to pick and choose which parts > of which standard to apply. This might not suit those of a nervous > disposition who want everything laid out in black and white, but for > more adventurous souls, who are prepared to get a grip on the process > and use it to their advantage, it provides immense flexibility in how > the standards are applied. > > The reasons for this are obvious. The scope of the Machinery > Directive is so broad that it would be quite simply impossible to > create type C standards for every different type of machine. One > might argue, with some merit, that the scope of the LVD is no less > broad in its own way, but I think an analysis will show that the > hazards which are contained in most electrical equipment are of a > lesser range than those in machinery. > > I have to say that the Machinery Directive approach provides a lot > more exposure to poor standards writing since particularly the type > 'c' standards committees are often populated by people with a > particular axe to grind, and with too few others to be able to > balance their position. I've certainly concluded that one should not > necessarily believe everything which one reads in a type C standard. > However, the Directive is very clear that you do not necessarily need > to comply with the requirements of a standard, but if you do not you > will need to justify in your Technical File how it is that what you > have done as an alternative is adequate. The same possibility exists > within the LVD of course, but it seems to me that lot's a lot less > well understood or used. > > Overall, you really can't escape from the need for experience and > expertise if you are going to successfully comply with either > directive, and I realise that's not much comfort to people who are at > the bottom of the learning curve. It's true of any engineering > problem though (and it keeps people like me in work!). > > I'd also observe that the Machinery approach to standards is already > starting to creep into LVD compliance. EN 50366 is a case in point - > it's a standard which is focused on a particular type of hazard > rather than on a particular type of equipment. Likewise, for anything > with a laser in it, the LVD standard will probably refer to EN 60825 > rather than trying to give detailed requirements for laser safety. > > The new LVD looks a lot more like the Machinery Directive, in that it > has a much expanded set of essential requirements. I doubt we will > ever see a wholesale re-write of all the electrical equipment safety > standards to create a three tier structure such as the type A, B and > C machinery standards, but I think we will see more new standards > which deal with particular hazards rather than standards which deal > with particular groups of equipment. > > Sory if this is rather long winded and boring, but it seemed to me it > was worth putting on the record for those who are not already > familiar with the Machinery Directive. > > Regards > > Nick. > > > > At 6:21 pm +0100 19/4/06, John Woodgate wrote: > >In message <p06230916c06c146a6ccd@[192.168.1.62]>, dated Wed, 19 Apr > >2006, Nick Williams <[email protected]> writes > >>I do not agree. This approach may work for the LVD but it will > >>rapidly lead to a dead end when applied to equipment within the > >>scope of the Machinery Directive. > > > >Well, I was surprised to read what you wrote, because it's regularly > spot-on. > > <SNIP> > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. 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