Hi, Well here is the other side to keep it 50-50.
I have understood the requirement to be that the "O" symbol can only be used when all power has been disconnected from the unit. I believe that if you used a single pole switch on a grounded neutral system, it would be OK. Of course, this is only OK if you can be sure that you know which will be the neutral. Ned Ned Devine Program Manager III Entela, Inc. 3033 Madison Ave. SE Grand Rapids, MI 49548 616 248 9671 Phone 616 574 9752 Fax ndev...@entela.com e-mail -----Original Message----- From: geor...@lexmark.com [mailto:geor...@lexmark.com] Sent: Friday, April 27, 2001 12:47 PM To: Rick Linford Cc: emc-p...@majordomo.ieee.org Subject: Re: EN60950 (UL1950, IEC 60950) On off switch marking. Rick, My opinion based on my understanding of IEC 60950......... Whether an on/off switch breaks one or both sides of the line, the equipment will be either on or off respectively, as either breaks the electron path. It is true that breaking only one side may leave the electronics "hot" if the plug or socket allow for the neutral to be the "open" side. However, the device will be off. As I recall, the marking instructions you referenced make no mention of whether one or both of the mains leads are opened by the switch. Therefore, the "I" or "O" apply only to whether the device is on or off, which results from breaking either or both sides of the line. George Alspaugh Lexmark International Inc. "Rick Linford" <rlinford%sonicwall....@interlock.lexmark.com> on 04/27/2001 12:25:19 PM Please respond to "Rick Linford" <rlinford%sonicwall....@interlock.lexmark.com> To: emc-pstc%majordomo.ieee....@interlock.lexmark.com cc: (bcc: George Alspaugh/Lex/Lexmark) Subject: EN60950 (UL1950, IEC 60950) On off switch marking. Hi All, When a switch opens only one leg of the mains to control power to equipment should it be marked with the "l" and "O"? Background: Three different engineers from three different NRTLs indicated it is permitted, two even required it. A different engineer for one of the NRTLs and two other respected individuals indicate it is prohibited. It will be interesting if members of this list will have the same 50/50 split or if there is a correct answer. (single phase 100 to 240 VAC, 2A, 50-60 Hz, intended to be shipped US, Canada, EU and generally internationally) To help, IEC 60950 (1999), section 1.7.8.3 Symbols, is shown below. Where symbols are used on or near controls, for example switches, push button, etc., to indicate "ON" "OFF" conditions, they shall be the line l for "ON" and the circle O for "OFF" (60417-1-IEC-5007 and 60417-1-IEC-5008). For push-push type switches the symbol {line in side the circle} shall be used (60417-1-IEC-5010). It is permitted to use the symbols O and l to indicate the "OFF" and "ON" positions of any primary or secondary power switches, including isolating switches. A "STAND-BY" condition shall be indicated by the symbol {line breaking the circle at the top} (60417-1-IEC-5009). My bias was not included in the 50/50 statistics noted above but I believe it is required. Rick Linford Regulatory Engineer SonicWALL ------------------------------------------- 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," ------------------------------------------- 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,"
