There is always the old story of the manager of the service dept of skilled and trained people and he went on site to show them how to get it done, and promptly fell over dead just as he removed the green wire ground from the chassis. Assuming that because you manage trained, skilled, and experienced people, you too are of the same level, can lead to some awkward moments, like making THAT phone call back to the office.
Bill In the event of a national emergency, click on the following links to provide directions to your duly elected mis-representatives. http://www.usa.gov/Contact/Elected.shtml or... https://writerep.house.gov/writerep/welcome.shtml http://www.senate.gov/general/contact_information/senators_cfm.cfm if really desperate... http://www.usa.gov/Contact/Elected.shtml --- On Fri, 10/29/10, Richard Nute <[email protected]> wrote: From: Richard Nute <[email protected]> Subject: Re: Protection system fault-tolerance hierarchy? To: [email protected] Cc: [email protected] Date: Friday, October 29, 2010, 5:49 PM Hi Brian: > What are the legal effects on my employer for Ordinary vs. Skilled vs. Instructed Persons ? By law, I cannot answer this question. Ordinary persons cannot give legal advice. > How does this affect the concept of an existing hazard as compared to a fault condition ? This question doesn't make much sense to me, probably because I don't know your definition of "hazard." In IEC 62368-1 and HBSE, we don't use the word "hazard" as a noun. Instead, it is an adjective as in "hazardous energy source." A hazardous energy source requires a safeguard be interposed between the energy source and a body to prevent energy transfer to the body. Any product connected to mains has a hazardous energy source. You can't get rid of the hazardous energy source. Instead, you must mitigate the transfer of energy to a body part by interposing one or more safeguards. Fault conditions are of two types. One is the fault of an ordinary (non-safeguard) component or spacing. In this case, during and after the fault, all safeguards must be effective and mitigate the fault. The other is a fault of a safeguard. If the energy source is Class 3, then two safeguards are required. The fault of one safeguard is mitigated by the second safeguard. > UL says that "A skilled person is expected to use their training and experience to recognize energy sources capable of causing pain or injury and to take action to protect them from injury from those energies". This is quote from IEC 62368-1, 0.2.4. I'm not sure of the issue here. When you take the cover off of a power supply, the mains is right there for you to touch. But you don't because of your training and experience. That training and experience is a safeguard. > Do you think that now is the time to get some HBSE training, or will we see a national implementation of IEC62368-1 before the apocalypse ? Wait until you can read the IEC 60950-1 to IEC 62368-1 clause-by-clause comparison document now in its final stages of preparation by Ecma's TC12. Due in March, 2011. If you had attended the IEEE PSES Symposium a few weeks ago, you could also have attended UL's HBSE training. Plan on it for next year's Symposium in San Diego. Which apocalypse? Political, economic, environmental, jihad, Armageddon? > AFAIK, if a box allows contact that exceeds a certain voltage or current or power, there is a hazard, for all people. Am I being a primitive tribal idiot ? Of course not. Existing standards have led you to this conclusion, and it makes for a safe box. In IEC 62368-1, neither an ordinary person nor an instructed person can have contact with a Class 3 energy source. Safeguards must be provided to prevent contact. This is no different than today's standards except we identify the "thing" that prevents the contact as a "safeguard." However, IEC 62368-1 considers behavior as a safeguard! In IEC 62368-1, a skilled person uses his training and experience to avoid contact as the safeguard against a Class 3 energy source. In IEC 62368-1, electric shock requires BOTH voltage and current to exceed the specified limits. One does not get a shock from a 12- volt car battery. Likewise, if leakage current is less than 0.5 mA, one does not get an electric shock regardless of voltage. In IEC 62368-1, there is no limitation on contact with power. > Can I assume that if UL/EN62368-1 gets published prior to the apocalypse, that the apocalypse as a procedural device can be certified for use by Skilled and certain Instructed Persons. Yes. But you know the adage about "assume." At the moment, neither UL nor EN will publish the 1st edition. They're waiting for the 2nd edition, which should be published in 2013. Best regards, Rich - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. 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Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]>
