Long ago (earlier '80's) and not so far away, The disconnect, double pole, had to be located so that is was visible and RED and reachable (front or front side) by the user-operator. Then it has to be marked with |/0 because some might not know English ON and OFF. I think the 1 was tried first but for some arcane reason the vertical bar was put in it's place. Now this caused all sorts of issues withe EMC. The disconnect had to be between the mains line cord and the filter, but no one wanted to put a line cord into the front of a unit. Imagine routing the external or unfiltered power cord back and forth inside the unit Very inventive mechanical gymnastics were developed to accomplish that. The one I liked best was the front switch was mechanically linked, a little rod, to disconnect switch located on the power supply at the rear. Another solution was a very long power supply internally divided into two shielded sections, mains plugged into the rear, pass through the unfiltered but shielded channel to the big red switch which connected to the AC filters into the filtered side. That one turned into a good exercise for mounting redundant hot swappable power supplies. - Bill
________________________________ From: John Woodgate <[email protected]> To: [email protected] Sent: Sat, February 27, 2010 8:57:50 AM Subject: Re: O and | symbols -- a bit of history In message <000001cab7af$41716230$c4542690$@com>, dated Sat, 27 Feb 2010, Ronald R. Wellman <[email protected]> writes: > Finally, what is sometimes ridiculous about labels and symbols is where they are on a product and whether they can be seen under normal use. If the O/| symbols are next to a mains power switch located on the back of an instrument, what good is that? You can't see the symbols in normal use. Those who do not learn from history are required to repeat the experience. At one time, at least one safety standard simply did not allow the disconnect to be on the back panel. > However, when Company Industrial Design folks have their way, you most likely will be required to have a switch on the front of the product. Whether that is a mains disconnect or stand-by switch is left for discussion. If it's a stand-by switch, you probably won't get your Energy Star rating. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK I should be disillusioned, but it's not worth the effort. - 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. 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]> - 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. 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]>
