Re: [PSES] safety distances in DC/DC
I am afraid it is even worse for SELV than a search of "SELV" would appear. Some standards do not use the acronym and do not show up in a "SELV" search. Do a search for "safety extra-low voltage" and you get even more! Did not try expanding out the other acronyms. __ Dan Roman, N.C.E. IEEE Product Safety Engineering Society <mailto:dan.ro...@ieee.org> mailto:dan.ro...@ieee.org --Original Message-- From: Richard Nute Date: Jan 16, 2015 2:37:58 PM Subject: Re: [PSES] safety distances in DC/DC To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> See: <http://std.iec.ch/glossary?ref=extfooter> http://std.iec.ch/glossary?ref=extfooter Enter SELV, PELV, and FELV, and enjoy! There are many definitions of SELV and PELV. It would seem that every TC has its own definitions. Just 5 for FELV and they are consistent. Also, check out ELV (which makes the FELV inconsistent). 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 < <mailto:emc-p...@ieee.org> emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: <http://www.ieee-pses.org/emc-pstc.html> http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at <http://product-compliance.oc.ieee.org/> http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: <http://www.ieee-pses.org/> http://www.ieee-pses.org/ Instructions: <http://www.ieee-pses.org/list.html> http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: <http://www.ieee-pses.org/listrules.html> http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas < <mailto:sdoug...@ieee.org> sdoug...@ieee.org> Mike Cantwell < <mailto:mcantw...@ieee.org> mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: < <mailto:j.bac...@ieee.org> j.bac...@ieee.org> David Heald: < <mailto:dhe...@gmail.com> 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
Class II is a type of construction - not necessarily relevant to this thread ? Class 2 is a North American code stuff (similar to an LPS). Brian From: Scott [mailto:0182a58d8335-dmarc-requ...@ieee.org] Sent: Wednesday, January 21, 2015 9:19 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC Try class II, class 2, or current limiting devices. Scott B On Jan 21, 2015, at 11:15 AM, Dan Roman wrote: I am afraid it is even worse for SELV than a search of “SELV” would appear. Some standards do not use the acronym and do not show up in a “SELV” search. Do a search for “safety extra-low voltage” and you get even more! Did not try expanding out the other acronyms. Dan --Original Message-- From: Richard Nute Date: Jan 16, 2015 2:37:58 PM Subject: Re: [PSES] safety distances in DC/DC To: EMC-PSTC@LISTSERV.IEEE.ORG See: http://std.iec.ch/glossary?ref=extfooter Enter SELV, PELV, and FELV, and enjoy! There are many definitions of SELV and PELV. It would seem that every TC has its own definitions. Just 5 for FELV and they are consistent. Also, check out ELV (which makes the FELV inconsistent). 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
Try class II, class 2, or current limiting devices. Scott B > On Jan 21, 2015, at 11:15 AM, Dan Roman wrote: > > I am afraid it is even worse for SELV than a search of “SELV” would appear. > Some standards do not use the acronym and do not show up in a “SELV” search. > Do a search for “safety extra-low voltage” and you get even more! Did not > try expanding out the other acronyms. > Dan > --Original Message-- > > From: Richard Nute > Date: Jan 16, 2015 2:37:58 PM > Subject: Re: [PSES] safety distances in DC/DC > To: EMC-PSTC@LISTSERV.IEEE.ORG > > See: http://std.iec.ch/glossary?ref=extfooter > > Enter SELV, PELV, and FELV, and enjoy! > > There are many definitions of SELV and PELV. It > would seem that every TC has its own definitions. > > > Just 5 for FELV and they are consistent. > > Also, check out ELV (which makes the FELV > inconsistent). > > > 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 > > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas > Mike Cantwell > > For policy questions, send mail to: > Jim Bacher: > David Heald: > > - > > 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 > > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas > Mike Cantwell > > For policy questions, send mail to: > Jim Bacher > David Heald - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
I am afraid it is even worse for SELV than a search of "SELV" would appear. Some standards do not use the acronym and do not show up in a "SELV" search. Do a search for "safety extra-low voltage" and you get even more! Did not try expanding out the other acronyms. Dan --Original Message-- From: Richard Nute Date: Jan 16, 2015 2:37:58 PM Subject: Re: [PSES] safety distances in DC/DC To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> See: <http://std.iec.ch/glossary?ref=extfooter> http://std.iec.ch/glossary?ref=extfooter Enter SELV, PELV, and FELV, and enjoy! There are many definitions of SELV and PELV. It would seem that every TC has its own definitions. Just 5 for FELV and they are consistent. Also, check out ELV (which makes the FELV inconsistent). 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 < <mailto:emc-p...@ieee.org> emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: <http://www.ieee-pses.org/emc-pstc.html> http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at <http://product-compliance.oc.ieee.org/> http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: <http://www.ieee-pses.org/> http://www.ieee-pses.org/ Instructions: <http://www.ieee-pses.org/list.html> http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: <http://www.ieee-pses.org/listrules.html> http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas < <mailto:sdoug...@ieee.org> sdoug...@ieee.org> Mike Cantwell < <mailto:mcantw...@ieee.org> mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: < <mailto:j.bac...@ieee.org> j.bac...@ieee.org> David Heald: < <mailto:dhe...@gmail.com> 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
John I agree that huge progress has been made over the last 3 decades in particular, but I do think that issues like this (and I'm sure there are others) do need to be addressed if we are to make further significant progress. Therefore I think that point should be made to the chairmen of all the relevant TC's, and thus: - the TC's which are effectively "in disagreement" over their definitions and requirements for "the same things" should be clearly identified ; - the areas of disagreement, and the reasons why, should be identified; - these should be rationalised and "equalised" - but, if that does not resolve the issues then some "head-banging" (probably lead by the IEC & CENELEC) needs to take place to sort them out. That being my view (and that - like yourself! - having been in the regs & stds business for very many years), do ANY OF THE "SIGNIFICANT" CONTRIBUTORS TO THE FORUM (notably the chairmen of relevant TC's‼‼) have some sensible suggestions as to how these progress towards these objectives could be achieved? NB: for my part I would suggest that this issue should be raised at the next IEC &/or CENELEC top-level steering committee meetings for them to identify and chart some possible ways forward from where we are today. John Allen -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: 16 January 2015 22:06 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC In message , dated Fri, 16 Jan 2015, John Allen writes: >And, in that case, what would you suggest might be done about improving >the situation? I don't have a solution. Do you? -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
In message LH5RdgBAA==@blueyonder.co.uk>, dated Fri, 16 Jan 2015, John Allen writes: And, in that case, what would you suggest might be done about improving the situation? I don't have a solution. Do you? -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
In message /Ml8/oBAA==@blueyonder.co.uk>, dated Fri, 16 Jan 2015, John Allen writes: Thanks, and that's all probably true (especially the language issue), but surely the issue is that the definitions of safety-relating earthing and the relevant insulation requirements should be pretty basic (not "BASIC", as in "BASIC INSULATION") and consistent, is it not? IEC has moved a long way in that direction with 'insulation co-ordination', but it still isn't 100% effective. If that scenario is not the case, then the whole underlying concept of the "basic" safety requirements in international standards being "common" could be very severely undermined? Not, I think, 'very severely'. In any case, the advisory committee on safety keeps a watch. But IEC has a policy of not 'micromanaging' its technical committees, although it strays from that on occasion, which usually leads to trouble sooner or later. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
And, in that case, what would you suggest might be done about improving the situation? John Allen -Original Message- From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: 16 January 2015 21:28 To: 'John Woodgate'; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] safety distances in DC/DC John Thanks, and that's all probably true (especially the language issue), but surely the issue is that the definitions of safety-relating earthing and the relevant insulation requirements should be pretty basic (not "BASIC", as in "BASIC INSULATION") and consistent, is it not? If that scenario is not the case, then the whole underlying concept of the "basic" safety requirements in international standards being "common" could be very severely undermined? John Allen -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: 16 January 2015 21:02 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC In message , dated Fri, 16 Jan 2015, John Allen writes: > >That seems like a classic case of the IEC "management" not clearly >"laying down the law" on the need for the various TCs to ensure that >they operate in a consistent manner - maybe these terms should be >defined clearly in IEC 60050 It hasn't worked: look up 'level' in the whole of 600650 and you find about 50 definitions. >and for the various TCs to use those definitions very consistently, and >without deviation? Unfortunately, one size does not fit all. We don't have enough distinct English words. German is better, but we really need a fully agglutinative language to express all the subtle shades of meaning. (;-) >(or have I just opened another can of worms that nobody wants to get to >grips with?) Substantially. It's very difficult to get people who are able (and funded) to do terminology work, and the present chaos would take an infinite team of monkeys for ever to sort out, especially as terms are being defined, or re-defined, all the time. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
John Thanks, and that's all probably true (especially the language issue), but surely the issue is that the definitions of safety-relating earthing and the relevant insulation requirements should be pretty basic (not "BASIC", as in "BASIC INSULATION") and consistent, is it not? If that scenario is not the case, then the whole underlying concept of the "basic" safety requirements in international standards being "common" could be very severely undermined? John Allen -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: 16 January 2015 21:02 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC In message , dated Fri, 16 Jan 2015, John Allen writes: > >That seems like a classic case of the IEC "management" not clearly >"laying down the law" on the need for the various TCs to ensure that >they operate in a consistent manner - maybe these terms should be >defined clearly in IEC 60050 It hasn't worked: look up 'level' in the whole of 600650 and you find about 50 definitions. >and for the various TCs to use those definitions very consistently, and >without deviation? Unfortunately, one size does not fit all. We don't have enough distinct English words. German is better, but we really need a fully agglutinative language to express all the subtle shades of meaning. (;-) >(or have I just opened another can of worms that nobody wants to get to >grips with?) Substantially. It's very difficult to get people who are able (and funded) to do terminology work, and the present chaos would take an infinite team of monkeys for ever to sort out, especially as terms are being defined, or re-defined, all the time. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
In message aKojswBAA==@blueyonder.co.uk>, dated Fri, 16 Jan 2015, John Allen writes: That seems like a classic case of the IEC "management" not clearly "laying down the law" on the need for the various TCs to ensure that they operate in a consistent manner - maybe these terms should be defined clearly in IEC 60050 It hasn't worked: look up 'level' in the whole of 600650 and you find about 50 definitions. and for the various TCs to use those definitions very consistently, and without deviation? Unfortunately, one size does not fit all. We don't have enough distinct English words. German is better, but we really need a fully agglutinative language to express all the subtle shades of meaning. (;-) (or have I just opened another can of worms that nobody wants to get to grips with?) Substantially. It's very difficult to get people who are able (and funded) to do terminology work, and the present chaos would take an infinite team of monkeys for ever to sort out, especially as terms are being defined, or re-defined, all the time. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
Then the UAP (IEC :D) will now declare independence from the rest of the Universe :D! -Original Message- From: Brian Oconnell [mailto:oconne...@tamuracorp.com] Sent: 16 January 2015 20:20 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC The Union of Allied Planets does not desire the overt and published knowledge of 'FELV', and would prefer that one not meddle in the tools of an Operative. Brian -Original Message- From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: Friday, January 16, 2015 12:07 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC Yes, I'll run - but in which direction for "safety"? (and that's the problem here as well: to SELV, PELV, FELV or "somewhere" / "something else" ?) ;-) John -Original Message- From: Kunde, Brian [mailto:brian_ku...@lecotc.com] Sent: 16 January 2015 19:59 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC John, when you are visited by two men in suits with blue nitrate gloves and your nose and eyes start to bleed, RUN!! "Two by two, hands or blue" - River (Firefly) The other Brian -Original Message- From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: Friday, January 16, 2015 2:48 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC Rich That seems like a classic case of the IEC "management" not clearly "laying down the law" on the need for the various TCs to ensure that they operate in a consistent manner - maybe these terms should be defined clearly in IEC 60050 and for the various TCs to use those definitions very consistently, and without deviation? (or have I just opened another can of worms that nobody wants to get to grips with?) John Allen W. London, UK -Original Message- From: Richard Nute [mailto:ri...@ieee.org] Sent: 16 January 2015 19:36 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC See: http://std.iec.ch/glossary?ref=extfooter Enter SELV, PELV, and FELV, and enjoy! There are many definitions of SELV and PELV. It would seem that every TC has its own definitions. Just 5 for FELV and they are consistent. Also, check out ELV (which makes the FELV inconsistent). 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Dougla
Re: [PSES] safety distances in DC/DC
The Union of Allied Planets does not desire the overt and published knowledge of 'FELV', and would prefer that one not meddle in the tools of an Operative. Brian -Original Message- From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: Friday, January 16, 2015 12:07 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC Yes, I'll run - but in which direction for "safety"? (and that's the problem here as well: to SELV, PELV, FELV or "somewhere" / "something else" ?) ;-) John -Original Message- From: Kunde, Brian [mailto:brian_ku...@lecotc.com] Sent: 16 January 2015 19:59 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC John, when you are visited by two men in suits with blue nitrate gloves and your nose and eyes start to bleed, RUN!! "Two by two, hands or blue" - River (Firefly) The other Brian -Original Message- From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: Friday, January 16, 2015 2:48 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC Rich That seems like a classic case of the IEC "management" not clearly "laying down the law" on the need for the various TCs to ensure that they operate in a consistent manner - maybe these terms should be defined clearly in IEC 60050 and for the various TCs to use those definitions very consistently, and without deviation? (or have I just opened another can of worms that nobody wants to get to grips with?) John Allen W. London, UK -Original Message- From: Richard Nute [mailto:ri...@ieee.org] Sent: 16 January 2015 19:36 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC See: http://std.iec.ch/glossary?ref=extfooter Enter SELV, PELV, and FELV, and enjoy! There are many definitions of SELV and PELV. It would seem that every TC has its own definitions. Just 5 for FELV and they are consistent. Also, check out ELV (which makes the FELV inconsistent). 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc
Re: [PSES] safety distances in DC/DC
Rich So what "good" technical reasons do they appear to give? (given the scope of the issue, they need to be damned good!) ISPCE 2015? - unfortunately my pension funds don't run to flights to/from the US (and all that goes with that), much as I would like to come (and having just spent nearly $3k, with more to come, on repairs to my car!) John -Original Message- From: Richard Nute [mailto:ri...@ieee.org] Sent: 16 January 2015 20:06 To: 'John Allen'; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] safety distances in DC/DC Hi John: The definitions represent "committee speak" without any reference to engineering or science. Supposedly, TCs are to follow the IEC basic safety standards. But, there is an out in that committees can divert from the basic standards if they have a "good" technical reason. See you at the Symposium (ISPCE 2015 in Chicago)? 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
Hi John: The definitions represent "committee speak" without any reference to engineering or science. Supposedly, TCs are to follow the IEC basic safety standards. But, there is an out in that committees can divert from the basic standards if they have a "good" technical reason. See you at the Symposium (ISPCE 2015 in Chicago)? 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
Yes, I'll run - but in which direction for "safety"? (and that's the problem here as well: to SELV, PELV, FELV or "somewhere" / "something else" ?) ;-) John -Original Message- From: Kunde, Brian [mailto:brian_ku...@lecotc.com] Sent: 16 January 2015 19:59 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC John, when you are visited by two men in suits with blue nitrate gloves and your nose and eyes start to bleed, RUN!! "Two by two, hands or blue" - River (Firefly) The other Brian -Original Message- From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: Friday, January 16, 2015 2:48 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC Rich That seems like a classic case of the IEC "management" not clearly "laying down the law" on the need for the various TCs to ensure that they operate in a consistent manner - maybe these terms should be defined clearly in IEC 60050 and for the various TCs to use those definitions very consistently, and without deviation? (or have I just opened another can of worms that nobody wants to get to grips with?) John Allen W. London, UK -Original Message- From: Richard Nute [mailto:ri...@ieee.org] Sent: 16 January 2015 19:36 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC See: http://std.iec.ch/glossary?ref=extfooter Enter SELV, PELV, and FELV, and enjoy! There are many definitions of SELV and PELV. It would seem that every TC has its own definitions. Just 5 for FELV and they are consistent. Also, check out ELV (which makes the FELV inconsistent). 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to
Re: [PSES] safety distances in DC/DC
John, when you are visited by two men in suits with blue nitrate gloves and your nose and eyes start to bleed, RUN!! "Two by two, hands or blue" - River (Firefly) The other Brian -Original Message- From: John Allen [mailto:john_e_al...@blueyonder.co.uk] Sent: Friday, January 16, 2015 2:48 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC Rich That seems like a classic case of the IEC "management" not clearly "laying down the law" on the need for the various TCs to ensure that they operate in a consistent manner - maybe these terms should be defined clearly in IEC 60050 and for the various TCs to use those definitions very consistently, and without deviation? (or have I just opened another can of worms that nobody wants to get to grips with?) John Allen W. London, UK -Original Message- From: Richard Nute [mailto:ri...@ieee.org] Sent: 16 January 2015 19:36 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC See: http://std.iec.ch/glossary?ref=extfooter Enter SELV, PELV, and FELV, and enjoy! There are many definitions of SELV and PELV. It would seem that every TC has its own definitions. Just 5 for FELV and they are consistent. Also, check out ELV (which makes the FELV inconsistent). 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
Rich That seems like a classic case of the IEC "management" not clearly "laying down the law" on the need for the various TCs to ensure that they operate in a consistent manner - maybe these terms should be defined clearly in IEC 60050 and for the various TCs to use those definitions very consistently, and without deviation? (or have I just opened another can of worms that nobody wants to get to grips with?) John Allen W. London, UK -Original Message- From: Richard Nute [mailto:ri...@ieee.org] Sent: 16 January 2015 19:36 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC See: http://std.iec.ch/glossary?ref=extfooter Enter SELV, PELV, and FELV, and enjoy! There are many definitions of SELV and PELV. It would seem that every TC has its own definitions. Just 5 for FELV and they are consistent. Also, check out ELV (which makes the FELV inconsistent). 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
See: http://std.iec.ch/glossary?ref=extfooter Enter SELV, PELV, and FELV, and enjoy! There are many definitions of SELV and PELV. It would seem that every TC has its own definitions. Just 5 for FELV and they are consistent. Also, check out ELV (which makes the FELV inconsistent). 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
Dear Boštjan: So in reality no way to avoid abnormal testing, since on transformer we always measure >42,4Vpk. Chances are, when you fault (short) primary to secondary, the switcher will shut down, and the output will not exceed SELV (will likely be zero). If this is the case, then no requirements for safety insulation between primary and secondary. The test proves that in the event of failure of the insulation primary-to-secondary there is no "hazardous" voltage. So, the insulation is not a safeguard and need not meet the requirements. On the other hand, no testing is necessary if the separation between the hazardous voltage and the secondary meets the requirements in the standard. Good luck, and 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
Bostian et al, Thanx for reporting another case of unexpected consequences on this forum. Doug Smith recently recounted his experience with a SMPS regurgitating a test impulse as large as, or larger, than the input pulse. I would also expect that this additional switching circuit would add to the touch current waveform as additional monophase spikes. The significance of these peaks would be related to their peak relationship to the other spikes in the touch current waveform. Please continue to share the ongoing saga leading to resolution; it's a great eye-opener for everyone on this list. :>) br, Pete Peter E Perkins, PE Principal Product Safety Engineer PO Box 23427 Tigard, ORe 97281-3427 503/452-1201 fone/fax p.perk...@ieee.org - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
In message utlook.com>, dated Thu, 15 Jan 2015, "Nyffenegger, Dave" writes: Grounded SELV is PELV in EN 60204-1. Indeed. My 'FELV' was wrong: FELV doesn't have reinforced insulation. PELV has reinforced insulation AND grounding. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
Dear Rich, Thank you. So in reality no way to avoid abnormal testing, since on transformer we always measure >42,4Vpk. Best regards, Bostjan From: Richard Nute [mailto:ri...@ieee.org] Sent: Thursday, January 15, 2015 1:52 AM To: Boštjan Glavič; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] safety distances in DC/DC Dear Boštjan: a) If internal distances input to output comply with functional insulation only, fault condition tests need to be performed on functional insulation (including transformer) in order to be sure that output remains SELV. In addition, transformer needs to pass electric strength test for basic insulation If the results of the fault test are that the output remains SELV, then basic insulation is not required. The test proves that the failure of the functional insulation does not result in a non-SELV output. If the results of the fault test are that the output exceeds SELV, then the insulation (between the 88 volts peak circuit and output) must be comprised of BOTH basic and supplementary insulation. IEC 60950-1 does not contemplate a SELV-to-SELV dc-dc converter that generates greater than SELV in the converter circuits and impressed on the isolation transformer and isolation insulation. That said, the dielectric strength test voltage (for 88 volts peak primary to the secondary) would be taken from Table 5, Part 2. Vb, for double or reinforced insulation, would be 1257 volts rms! a) If internal distances input to output comply with basic insulation, there is no need for fault condition tests. No. The insulation from the 88 volts peak circuits to the secondary (output) must have double or reinforced insulation. Clearances are specified in Table 2M, and would be 1.4 mm for reinforced insulation. Creepage distances are related to the r.m.s. voltage of the primary, 2.10.2.2. The r.m.s. of 88 volts peak is 62.2 or less, depending on waveshape. Creepage distances are specfied in Table 2N and would be 0.1 or 0.16 depending on material. But, a creepage (physically) cannot be less than a clearance, so the clearance requirement of 1.4 mm applies. Note that some authorities would require isolation of the input from the 88 volts peak circuits. A fault test will prove that this cannot happen and that only functional insulation is required. (The law of conservation of energy.) a) Since measured working voltage 88Vpk is above TNV-2 limit it is considered as hazardous secondary voltage and we need reinforced insulation in order to avoid fault condition tests. Yes. But, if fault tests prove that the output remains SELV, then there is no requirement for reinforced insulation. Good luck, and 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
Grounded SELV is PELV in EN 60204-1. -Dave -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Wednesday, January 14, 2015 1:59 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC In message , dated Wed, 14 Jan 2015, Brian Oconnell writes: >Other than BS7671/IEC60364, what standards or codes use 'FELV' and what >is intended end-use? I've never done a search. The issue with floating SELV is that it could become live but remain undetected until someone touches it. The issue with FELV is that it might be called on to carry mains fault current but the wire size would be inadequate. Both scenarios are very improbable, but the consequences could be very serious. You get to choose! -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
Dear Boštjan: a) If internal distances input to output comply with functional insulation only, fault condition tests need to be performed on functional insulation (including transformer) in order to be sure that output remains SELV. In addition, transformer needs to pass electric strength test for basic insulation If the results of the fault test are that the output remains SELV, then basic insulation is not required. The test proves that the failure of the functional insulation does not result in a non-SELV output. If the results of the fault test are that the output exceeds SELV, then the insulation (between the 88 volts peak circuit and output) must be comprised of BOTH basic and supplementary insulation. IEC 60950-1 does not contemplate a SELV-to-SELV dc-dc converter that generates greater than SELV in the converter circuits and impressed on the isolation transformer and isolation insulation. That said, the dielectric strength test voltage (for 88 volts peak primary to the secondary) would be taken from Table 5, Part 2. Vb, for double or reinforced insulation, would be 1257 volts rms! a) If internal distances input to output comply with basic insulation, there is no need for fault condition tests. No. The insulation from the 88 volts peak circuits to the secondary (output) must have double or reinforced insulation. Clearances are specified in Table 2M, and would be 1.4 mm for reinforced insulation. Creepage distances are related to the r.m.s. voltage of the primary, 2.10.2.2. The r.m.s. of 88 volts peak is 62.2 or less, depending on waveshape. Creepage distances are specfied in Table 2N and would be 0.1 or 0.16 depending on material. But, a creepage (physically) cannot be less than a clearance, so the clearance requirement of 1.4 mm applies. Note that some authorities would require isolation of the input from the 88 volts peak circuits. A fault test will prove that this cannot happen and that only functional insulation is required. (The law of conservation of energy.) a) Since measured working voltage 88Vpk is above TNV-2 limit it is considered as hazardous secondary voltage and we need reinforced insulation in order to avoid fault condition tests. Yes. But, if fault tests prove that the output remains SELV, then there is no requirement for reinforced insulation. Good luck, and 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
In message , dated Wed, 14 Jan 2015, =?iso-8859-2?Q?Bo=B9tjan_Glavi=E8?= writes: I was talking about component level converter that is usually mounted to PCB. No plug provided. Output is SELV. I was asking how to evaluate internal distances input to output. I believe there is no real harmonization between testing laboratories on this subject. These are surely sealed units, aren't they? You cannot see inside, so you have to refer your questions to the manufacturer, such as 'What grade of insulation according to IEC/EN 60950-1 is there between the input and the output?'. If you don't get answers you like, don't buy the product. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
In message .com>, dated Wed, 14 Jan 2015, Brian Oconnell writes: Other than BS7671/IEC60364, what standards or codes use 'FELV' and what is intended end-use? I've never done a search. The issue with floating SELV is that it could become live but remain undetected until someone touches it. The issue with FELV is that it might be called on to carry mains fault current but the wire size would be inadequate. Both scenarios are very improbable, but the consequences could be very serious. You get to choose! -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
Dear all, Thank you for your feedbacks. I was talking about component level converter that is usually mounted to PCB. No plug provided. Output is SELV. I was asking how to evaluate internal distances input to output. I believe there is no real harmonization between testing laboratories on this subject. Best regards, Bostjan Boštjan Glavič Vodja laboratorija, Laboratorij za elektroniko Head of Laboratory, Laboratory of Electronic Engineering [SIQlogo60px] www.siq.si<http://www.siq.si/> SIQ Ljubljana, Trzaska c. 2, SI-1000 Ljubljana, Slovenia, VAT ID: SI23509678 t +386 (0)1 4778 265, m +386 (0)41 391 283, f +386 (0)1 4778 444 On 14. jan. 2015, at 19:49, "Brian Oconnell" mailto:oconne...@tamuracorp.com>> wrote: Other than BS7671/IEC60364, what standards or codes use 'FELV' and what is intended end-use? Have never seen in NFPA70, but remember something in IEC60364 that restricts plug configurations. Brian -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Wednesday, January 14, 2015 9:34 AM To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] safety distances in DC/DC In message mailto:blupr02mb11639e55993bee1e45c09ffc1...@blupr02mb116.namprd02.prod.outlook> .com>, dated Wed, 14 Jan 2015, Brian Oconnell mailto:oconne...@tamuracorp.com>> writes: if the input and/or output referenced to reliable ground bond. Note that only(?) 60950-1 allows SELV to be grounded. Other standards require it to float, and call the grounded kind FELV (Functional...). -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk<http://www.jmwa.demon.co.uk> When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 mailto:emc-p...@ieee.org>> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas mailto:sdoug...@ieee.org>> Mike Cantwell mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher: mailto:j.bac...@ieee.org>> David Heald: mailto: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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
Other than BS7671/IEC60364, what standards or codes use 'FELV' and what is intended end-use? Have never seen in NFPA70, but remember something in IEC60364 that restricts plug configurations. Brian -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Wednesday, January 14, 2015 9:34 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] safety distances in DC/DC In message , dated Wed, 14 Jan 2015, Brian Oconnell writes: > if the input and/or output referenced to reliable ground bond. Note that only(?) 60950-1 allows SELV to be grounded. Other standards require it to float, and call the grounded kind FELV (Functional...). -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
In message .com>, dated Wed, 14 Jan 2015, Brian Oconnell writes: if the input and/or output referenced to reliable ground bond. Note that only(?) 60950-1 allows SELV to be grounded. Other standards require it to float, and call the grounded kind FELV (Functional...). -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk When I turn my back on the sun, it's to look for a rainbow John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] safety distances in DC/DC
a. Depends on measured WV of the converter. Fault tests non sequitur for functional insulation as basis for protection from shock or prevention of fire. Fault tests are indicated only to demonstrate SELV during fault. By definition, FI does not provide any level of protection. Di-electric withstand to indicate BI performance levels for FI also non-sequitur unless you want this as part of your internal product spec. b. Use of spacing and materials to meet BI requirements has nothing to do with unit's performance during abnormal operating conditions. c. Unknown as depends on where the WV was measured and if input and output terminals remain reliably SELV during faults and abnormal operating conditions and if the input and/or output referenced to reliable ground bond. See table 2H. Brian From: Boštjan Glavič [mailto:bostjan.gla...@siq.si] Sent: Tuesday, January 13, 2015 10:03 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] safety distances in DC/DC Dear experts, We are evaluating DC/DC converter with SELV-in/SELV-out specification according to IEC 60950-1. We have measured internal working voltages on the transformer between input and output side and they were above SELV circuit (88Vpk). Could you please comment following scenarious: a) If internal distances input to output comply with functional insulation only, fault condition tests need to be performed on functional insulation (including transformer) in order to be sure that output remains SELV. In addition, transformer needs to pass electric strength test for basic insulation b) If internal distances input to output comply with basic insulation, there is no need for fault condition tests. c) Since measured working voltage 88Vpk is above TNV-2 limit it is considered as hazardous secondary voltage and we need reinforced insulation in order to avoid fault condition tests. I am quite positive about scenario a) and c) but not sure about scenario b). Thank you for your support. Best regards, Boštjan Glavič - 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 All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
