Hi Nick,
The frustrations you document below are indeed understandable. If I may
point out however, there are some very good reasons why one standard should
make reference to another standard rather than include what may be believed
to be the complete or appropriate requirement from another standard.
Some of the reasons are:
1. any group of people involved in the preparation of an international
standard are accepted as reasonably expert in their field. Typically
therefore they are not acknowledged as experts in terms of another
standard, developed by another group of experts (committee) and as such may
unwittingly include the wrong requirements or include the requirement in
the wrong context;
2. all standards, particularly standards involving complex requirements,
should be read in full regarding their requirements. It is unwise to
attempt to isolate one clause or requirement in a standard as other parts
of the standard may well impact that clause;
3. if requirements from another standard are included, the moment the
other standard changes or modifies that requirement in any way the first
standard which has included the requirement is immediately out of date and
it too now requires modification to come into line with the modified
requirement in the other standard. Unnecessary duplication of effort and
expense (expenses which would need to be passed on to the purchaser of the
standard anyway). When a standard includes requirements from several other
standards it is an impossible and unrealistic task for the committee
responsible to keep a watching brief on all requirements in all standards
they have included requirements from; and
4. lastly, the IEC have general rule that after a standard has had 4
Amendments a new Edition of the entire standard must be published. This
again introduces unnecessary work and costs and would result in a marked
decrease in the period for which your standard that you purchased would be
current (ie the user would need to purchase the complete standard far more
frequently).
I am not sure I have included all the reasons however these are the main
ones. By the way, the standard you picked (IEC 60950) is one of the more
complex standards and as such is an excellent example of point 2 above I
believe.
Hope this provides some appreciation for some of the reasons most standards
no longer include requirements from other standards and instead just make
reference to the applicable standard.
Best regards,
Kevin
>
>
> Very little to do with the topc in the header I'm afraid, but...
>
> This post raises a point which has concerned me for some time, and which
> I'd be interested in opinions from other sources on.
>
> It is my impression (and it is only an impression - I have made no
attempt
> to gather objective evidence) that it is increasingly common for new
> standards to be issued, and existing standards to be modified, with
> certain tests removed from the standard itself and replaced with a cross
> reference to another harmonised or IEC standard.
>
> This seems to be particularly true of mechanical tests (e.g. vibration,
> drop test, enclosure access).
>
> Standards writers would doubtless argue that this makes good sense
because
> it make updating these specialist requirements easier, and it
standardises
> (!) the requirements between different documents.
>
> Personally, it's a practice which annoys me and I think it is bad
standard
> making. I say this on two grounds:
>
> 1. Few things annoy me more in relation to standards than spending a shed
> load of money on an enormous document which is supposed to be a
> comprehensive set of requirements and then discovering I have to spend a
> load more money to buy subsidiary standards in order to find out what the
> requirements of the main standard really are. It's difficult not to
> conclude that this is profiteering by the standards publishing bodies.
>
> 2. When you get a test certificate for an appliance which has been tested
> to (say) BSEN60950:1992 it would be nice to think you could tell exactly
> what requirements have been applied to the product. However, if one has
to
> know which version of the subsidiary standards have been applied, the
> process quickly becomes a nightmare.
>
> 60950 may be a bad choce to illustrate this phenomenon - I'm not very
> familiar with it, although I know lots of other people on this list are.
> The problem is particularly prevalent in machinery standards, but it is
> also creeping into the main electrical safety standards (e.g. EN60204 and
> 60335).
>
> Personally I can see no reason not to give the full requirements of the
> subsidiary standard in the main standard, and to cross reference the
> subsidiary standard as well. That way, when you buy the main standard you
> get a completely comprehensive set of requirements, but if you want to
see
> what might develop you can look at how the subsidiary standards have been
> changed since the main standard was last issued.
>
> I'd be interested in commends from others on this topic - especially
anyone
> on the list who is closely involved in standards writing. Maybe if enough
> people agree with me I could turn this into a comment to be sent to
someone
> who ought to listen.
>
> Regards
>
> Nick.
>
>
>
>
>
> At 12:17 -0400 24/9/99, Peter E. Perkins wrote:
> > PSNet
> >
> > The announcement of the availability of the update to IEC 60990,
> >shown below, has been circulating for a short time now. As Convenor
> >(Chairman) of this committee I had not generally circulated it to the
PSNet
> >since it is not a product standard but a basic standard to be used by
> >product standards writing committees. As is usually the case, the
> >information in basic standards is excerpted or summarized in product
> >standards. Two IEC committees have been integrating this information
into
> >their product standards for some time; IEC TC66/IEC 61010 (and the 1010
> >derivitive EN, CSA and UL standards) and IEC TC74/IEC 60950 (and the 950
> >derivitive EN, CSA and UL standards). The implementation of these
> >requirements into these two standards families is done in a slightly
> >different way and neither is a full copy of the IEC 60990 set of
> >recommended requirements. The certification requirements for the
products
> >are contained in the end product standard. We expect to see ongoing
> >changes to the measurement of touch current at the product level to
> >accommodate the introduction of new technology which changes touch
current
> >and exposes the user to this aspect of electric shock in some new way.
If
> >you are a designer of test equipment making this measurement or want to
see
> >the latest information regarding the measurement of touch current you
> >should buy a copy of this standard.
> >
>
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Best regards,
Kevin Richardson
Stanimore Pty Limited
(Technology Products Standards, Regulations and Compliance Specialists)
Ph: 02-4329-4070 Fax: 02-4328-5639
Int'l: +61-2-44329-4070 +61-2-4328-5639
Email: k...@compuserve.com (Internet)
kevin.richard...@ieee.org (Alternate Internet #1)
k...@technologist.com (Alternate Internet #2)
100356,374 (Compuserve)
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