Some safety standards peg it at 60Vdc (dry locations) and I recall 61010 said 70Vdc in one version.
And some say 42.4Vpk, 30Vrms. Ralph McDiarmid, AScT Compliance Engineering Group Xantrex Technology Inc. From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of 'Rich Nute' Sent: Thursday, July 30, 2009 8:50 PM To: lauren_cr...@amat.com Cc: emc-p...@ieee.org Subject: RE: "safe" voltage differences between UL 1703 and IEC 61140 Hi Lauren: The IEC and UL are not harmonized with respect to safe DC voltages. DC does not cause tetanization, and requires very much more current to cause fibrillation than AC. So, higher DC voltages provide the same effect as AC voltages. UL has taken the peak of the AC (30 V) as the limit for DC (42.4 V). For telephone circuits, UL uses 70 V DC. All we can say is that the two organizations are not yet fully harmonized as to hazardous voltages. Best regards, Rich -----Original Message----- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of lauren_cr...@amat.com Sent: Thursday, July 30, 2009 7:18 AM To: emc-p...@ieee.org Subject: "safe" voltage differences between UL 1703 and IEC 61140 A colleague has stumped me with the following question. ================== A supplier of a Photovoltaic panel cited IEC 61140 (Protection against electric shock – Common aspects for installation and equipment) as referencing a "safe" voltage to be as high as 120 Vdc. This is puzzling because UL 1703 (Flat-Plate Photovoltaic Modules and Panels) appears to define the electric shock threshold at 30 Vdc. How can electric shock threshold for UL 1703 be set at 30 Vdc, but IEC 61140 considers the upper "safe" limit to be 120 Vd.c.? ************************************** ************************************************************************ IEC 61140 - Protection against electrical shock - common aspects for installation and equipment Section 7.4 Class III Equipment Equipment relying on limitation of voltage to ELV values as provision for basic protection and with no provision for fault protection. 7.4.1 Voltages 7.4.1.1 Equipment shall be designed for a maximum nominal voltage not exceeding 50V a.c. or 120 V d.c. ripple free. ... NOTE 2: According to clause 411 of IEC 60264-4-41, class III equipment is accepted only for connection to SELV and PELV systems. ************************************** ************************************************************************** Any ideas on the rational behind this difference? Regards, Lauren Crane Product Regulatory Analyst Corporate Product EHS Lead Applied Materials Inc. Austin, TX 512 272-6540 [#922 26540] --------- - 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 <emc-p...@ieee.org> 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 <emcp...@socal.rr.com> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com> - 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 <emc-p...@ieee.org> 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 <emcp...@socal.rr.com> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com>
