PSNet
We've had a healthy interchange here about the desirability and
possibility of having a single safety standard. there has also been some
controversy over specifics...
I think our set of exchanges exemplifies the real world - differences of
opinion over a significant issue of change...
Rich Nute is correct (and most can agree) - there is a sound technical
basis for requirements that can be stated, but...
Well, look at the real world. Already some have said here that they
can't use the usual/normal rules - they need something different (an exception,
if you will)... Everyone believes that their case is an exception - and wants to
argue about it with someone (test lab, standards committee, here, etc... )
The historical standards developers (mostly test houses with some
manufacturers input) have been responsive to these marketing pressures and have
developed specific standards for each group... ergo, a plethora of standards
covering many subjects... In North America there have been significantly more
standards than in the European system; so we might say that the NA system has
been more responsive to the special needs of manufacturers than the European
system...
In one effort with which many of us are familiar - the development of a
single standard for commercial, digital electronic equipment - we can chronicle
the ongoing saga, identifying the big bumps as we go along... there are several
folks on the PSNet that have been involved in this since ancient times.. (no
reference to your age Manning)... It was a momentous effort to combine IEC 380
& 435 to get IEC 950... and the resulting standard was the best (or worst) of
both worlds... adding the telecomm requirements into IEC 950 has been ongoing
for more that 5 years already and we're still haggling over the details... more
frustrating than these fundamental issues is that TC74 has spent most of the
last 10 years (and 4 amendments to IEC 950) modifying the standard to settle
arguments between manufacturers and test houses... no time to focus on the
basics...
There are methods for dealing with all of this - each with its attendant
benefits and penalties... the IEC 335 approach with the part 1 general
requirements and many (a hundred or more) specific product sections has been
discussed already... hunting back and forth to determine the full requirement
is my biggest complaint... perhaps an electronic version of the standard with
auto integration of requirements to fit each case would take care of this...
It sure would be nice if we could adopt the (continual) comment of our
TC74 Netherlands member (thanx, Theo Wenholdt) - a short statement of principles
(10 commandments for safety?) and a lot of common sense in the application...
This would work better in some situations than in others... for instance,
mechanical engineers can usually tell you the factor of safety designed into any
part (which is based upon the properties of the materials used)... electrical
engineers usually cannot tell you the factor of safety involved in any aspect of
their design... as safety engineers we try to understand these issues (as
expressed in some standard) and properly apply them in our evaluation of the
equipment...
so, remember that the world is more complicated than just identifying
the
technical issues; although we should continue to keep the focus on the
technical...
keep up the good discussion...
:>) br, Pete Perkins
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Peter E Perkins
Principal Product Safety Consultant
Tigard, ORe 97281-3427
+1/503/452-1201 phone/fax
p.perk...@ieee.org email
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