John, I have no problem with your second paragraph; it makes sense.
However, I believe that standards should use all three precepts as necessary rather than an ascension order as you state. For example, for fire mitigation, UL uses all three approaches: performance (subjects plastics to fire tests), construction (types of enclosure, hole openings), and design (parts in low current & power limited circuits have different requirements). In contrast, Bellcore GR-63-CORE torches the complete system to prove fire safety and subjects printed circuits to airborne contaminants (thereby absolutely destroying them) to prove pass or fail parameters by performance. I think that it is wrong and unreasonable to destroy equipment that costs hundreds of thousands of dollars to prove a pass or fail condition.. And unnecessary when judicious design and construction requirements could achieve similar results. I think that all three are necessary in proper combination. UL is not a saint, but I believe that they have a more rational approach than burning equipment,-- like witches were burned in the Dark Ages to prove their fair or foul status. Tania Grant taniagr...@msn.com ----- Original Message ----- From: John Woodgate Sent: Wednesday, June 20, 2001 9:13 AM To: emc-p...@majordomo.ieee.org Subject: Re: You won't believe this ... Well, maybe you will. <002501c0f905$794dabe0$3e3e3...@corp.auspex.com>, Doug McKean <dmck...@corp.auspex.com> inimitably wrote: >1. Have any you ever run into something > like this before? > >2. If you have, what did you do about it? I would say that a safety standard that specifies a cfm rating for a fan is a badly-drafted standard. I would press to get the standard changed. What matters for safety is the temperature that parts can reach. If they are OK, under both normal and fault conditions, the equipment should pass. This is an example of a fundamental principle of prescriptive standardization: 1. If possible, specify performance: it's what matters and is usually easy to verify. 2. If it isn't possible/practicable to verify performance (e.g. if long- term durability is involved), specify construction. 3. If it isn't possible/practicable to specify construction (e.g. because many constructions would be satisfactory), specify design. In this case, specifying performance - temperature rises under normal and fault conditions - is the normal practice. Specifying the cfm is specifying design, and there seems no good reason for that. -- Regards, John Woodgate, OOO - Own Opinions Only. Phone +44 (0)1268 747839 Fax +44 (0)1268 777124. http://www.jmwa.demon.co.uk Why not call a vertically- applied manulo-pedally-operated quasi-planar chernozem-penetrating and excavating implement a SPADE? ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
