Re: [PSES] POE creepage clearances
Hi Ian: I think the short answer to your question is that under 60950 there are no requirements for creepage and clearance distance between the Ethernet circuit and ordinary SELV circuits that are user-contactable. This is because under 60950, Ethernet is classified as an SELV circuit. There are no requirements to separate one SELV circuit from another. Where this issue becomes confusing is that under the Ethernet 802.3 standard, an Ethernet port must provide a 1500 VRMS isolation barrier between the Ethernet conductors and earth. This is a legacy requirement whose origins seem to have been lost in the sands of time. However, I believe the consensus view is that the original intent of this requirement was to protect against ground loops and was not related to user safety. Nevertheless, the 802.3 isolation requirement has sometimes been treated as though it is a safety requirement. Note that the 802.3 requirement is for a simple dielectric test, with no reference to creepage, clearance, or distance through solid insulation. So, in principle, there are no safety isolation requirements for your application, since both of the proposed power supplies have a SELV output. This makes the entire device a SELV circuit (unless there are other ports on the device that are not SELV). Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) j...@randolph-telecom.com http://www.randolph-telecom.com Dear colleagues We are developing a hand held product that is powered from +48V DC over Ethernet or from an external +12V DC wall wart PSU. The maximum internal voltage will be the +48V POE. Can anyone let me know what the creepage and clearance requirements between the primary Ethernet circuit and the secondary circuit. The product will be tested to IEC 60950 or possibly IEC 60065 so I am assuming a safety isolation creepage clearance is required. Many thanks in advance; Ian McBurney Design Engineer Allen Heath Ltd Kernick Industrial Estate Penryn, Cornwall TR10 9LU United Kingdom +44 (0)1326 370121 ian.mcbur...@dmh-global.com www.allen-heath.com A DMH Pro Company. - 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.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://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...@radiusnorth.net 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.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://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...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.org David Heald dhe...@gmail.com
Re: [PSES] POE creepage clearances
Be careful Joe, There is a UL PAG that says that PoE must be treated as a TNV1, but overvoltage tests can be waived from Annex NAC. It is a botched PAG that needs to be fixed for other reasons. Also if it crosses the boundary between buildings it needs to be treated as TNV-1 even for international safety standards which may impose creepage and Clearance distances. Also people forget there can be a lot of current coming from a shared PoE DC supply and eventhough safety requirement creepage and clearances do not apply between the high and low voltage rails it is good to impose separation so you don't have a fire. Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.commailto:jim.wi...@adtran.com From: Joe Randolph [mailto:j...@randolph-telecom.com] Sent: Monday, November 26, 2012 1:43 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] POE creepage clearances Hi Ian: I think the short answer to your question is that under 60950 there are no requirements for creepage and clearance distance between the Ethernet circuit and ordinary SELV circuits that are user-contactable. This is because under 60950, Ethernet is classified as an SELV circuit. There are no requirements to separate one SELV circuit from another. Where this issue becomes confusing is that under the Ethernet 802.3 standard, an Ethernet port must provide a 1500 VRMS isolation barrier between the Ethernet conductors and earth. This is a legacy requirement whose origins seem to have been lost in the sands of time. However, I believe the consensus view is that the original intent of this requirement was to protect against ground loops and was not related to user safety. Nevertheless, the 802.3 isolation requirement has sometimes been treated as though it is a safety requirement. Note that the 802.3 requirement is for a simple dielectric test, with no reference to creepage, clearance, or distance through solid insulation. So, in principle, there are no safety isolation requirements for your application, since both of the proposed power supplies have a SELV output. This makes the entire device a SELV circuit (unless there are other ports on the device that are not SELV). Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) j...@randolph-telecom.com http://www.randolph-telecom.comhttp://www.randolph-telecom.com/ Dear colleagues We are developing a hand held product that is powered from +48V DC over Ethernet or from an external +12V DC wall wart PSU. The maximum internal voltage will be the +48V POE. Can anyone let me know what the creepage and clearance requirements between the ?primary? Ethernet circuit and the ?secondary? circuit. The product will be tested to IEC 60950 or possibly IEC 60065 so I am assuming a safety isolation creepage clearance is required. Many thanks in advance; Ian McBurney Design Engineer Allen Heath Ltd Kernick Industrial Estate Penryn, Cornwall TR10 9LU United Kingdom +44 (0)1326 370121 ian.mcbur...@dmh-global.commailto:ian.mcbur...@dmh-global.com www.allen-heath.comhttp://www.allen-heath.com/ A DMH Pro Companyhttp://www.dmh-global.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.orgmailto: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://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...@radiusnorth.netmailto:emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.orgmailto:mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.orgmailto:j.bac...@ieee.org David Heald dhe...@gmail.commailto: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.orgmailto: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://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee
Re: [PSES] POE creepage clearances
Hi Joe, I agree that an Ethernet circuit would be considered to be an SELV circuit and that would be true if the POE circuit were completely on premise generally, which would categorize this as a Class III product according to IEC/UL 60950-1 2nd Ed. given that the external power supply is a limited power source (LPS). However, TNV-1 creepage/clearance requirements would apply if the POE were to be exposed to overvoltages from telecommunication networks (essentially off premise) requiring Basic insulation. I make this distinction as Ian did not mention where the POE circuit originates. Best regards, Ron From: Joe Randolph [mailto:j...@randolph-telecom.com] Sent: Monday, November 26, 2012 12:43 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] POE creepage clearances Hi Ian: I think the short answer to your question is that under 60950 there are no requirements for creepage and clearance distance between the Ethernet circuit and ordinary SELV circuits that are user-contactable. This is because under 60950, Ethernet is classified as an SELV circuit. There are no requirements to separate one SELV circuit from another. Where this issue becomes confusing is that under the Ethernet 802.3 standard, an Ethernet port must provide a 1500 VRMS isolation barrier between the Ethernet conductors and earth. This is a legacy requirement whose origins seem to have been lost in the sands of time. However, I believe the consensus view is that the original intent of this requirement was to protect against ground loops and was not related to user safety. Nevertheless, the 802.3 isolation requirement has sometimes been treated as though it is a safety requirement. Note that the 802.3 requirement is for a simple dielectric test, with no reference to creepage, clearance, or distance through solid insulation. So, in principle, there are no safety isolation requirements for your application, since both of the proposed power supplies have a SELV output. This makes the entire device a SELV circuit (unless there are other ports on the device that are not SELV). Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) j...@randolph-telecom.commailto:j...@randolph-telecom.com http://www.randolph-telecom.comhttp://www.randolph-telecom.com/ Dear colleagues We are developing a hand held product that is powered from +48V DC over Ethernet or from an external +12V DC wall wart PSU. The maximum internal voltage will be the +48V POE. Can anyone let me know what the creepage and clearance requirements between the ?primary? Ethernet circuit and the ?secondary? circuit. The product will be tested to IEC 60950 or possibly IEC 60065 so I am assuming a safety isolation creepage clearance is required. Many thanks in advance; Ian McBurney Design Engineer Allen Heath Ltd Kernick Industrial Estate Penryn, Cornwall TR10 9LU United Kingdom +44 (0)1326 370121 ian.mcbur...@dmh-global.commailto:ian.mcbur...@dmh-global.com www.allen-heath.comhttp://www.allen-heath.com/ A DMH Pro Companyhttp://www.dmh-global.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.orgmailto: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://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...@radiusnorth.netmailto:emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.orgmailto:mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.orgmailto:j.bac...@ieee.org David Heald dhe...@gmail.commailto: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.orgmailto: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://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...@radiusnorth.netmailto:emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.orgmailto:mcantw...@ieee.org For policy
Re: [PSES] POE creepage clearances
Jim, Ron: I agree that *if* the Ethernet cable extends outside the building for a *considerable* distance, it's safety classification enters a no-man's land in terms of safety classification. UL attempted to address such situations with their PAG on POE, which states that POE lines that are routed outside should be treated as TNV-1, but ordinary POE that is routed inside can be treated as SELV. This leaves some ambiguity because often the manufacturer does not know whether the user's POE network uses outside lines. A few months ago, those of us on the IEEE Telecom TAC had a very robust discussion about this problem and possible ways to resolve it in a clear manner. Unfortunately, we were unable to come up with a simple solution. The fact remains that under IEC 69050 and it's national derivations, Ethernet is classified as SELV and for the vast majority of applications, this classification is entirely appropriate. Now that *some* users are stringing Ethernet cables outside, the question can be asked, at what cable length does my Ethernet cable become subject to the same safety threats as a TNV-1 circuit? The only official attempt to answer this question is the UL PAG for UL 60950, and even this attempt has some ambiguities. Given that the maximum length of an Ethernet cable is specified in 802.3 to be 100 meters, it can be argued that this is insufficient to create the same level of exposure hazard as a conventional phone line that can easily exceed 5000 meters. Getting back to Ian's original question, though, one could ask what the effect would be of classifying his Ethernet port as a TNV-1 circuit. I'm speaking from memory here, but as I recall the TNV-1 classification does not invoke explicit creepage and clearance distances (these are only called out for TNV-2 and TNV-3 circuits). I think the only isolation requirement for TNV-1 is a dielectric test of 1000 VRMS to user-contractible points and/or 1500 VRMS to hand-held items. In other words, if his design meets the 1500 VRMS isolation requirement called out in 802.3, it will also meet the TNV-1 isolation requirement in IEC 60950. Now I know that the TNV-1 requirements in IEC 60950 are expanded in the UL/CSA version to cover power cross testing, and the Australian version uses a higher isolation test. However, I'm not going to get caught up in these nuances unless Ian tells us these countries are important for his particular product, *and* that he thinks he has to classify his Ethernet interface as TNV-1. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) j...@randolph-telecom.com http://www.randolph-telecom.com Be careful Joe, There is a UL PAG that says that PoE must be treated as a TNV1, but overvoltage tests can be waived from Annex NAC. It is a botched PAG that needs to be fixed for other reasons. Also if it crosses the boundary between buildings it needs to be treated as TNV-1 even for international safety standards which may impose creepage and Clearance distances. Also people forget there can be a lot of current coming from a shared PoE DC supply and eventhough safety requirement creepage and clearances do not apply between the high and low voltage rails it is good to impose separation so you dont have a fire. Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com From: Joe Randolph [mailto:j...@randolph-telecom.com] Sent: Monday, November 26, 2012 1:43 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] POE creepage clearances Hi Ian: I think the short answer to your question is that under 60950 there are no requirements for creepage and clearance distance between the Ethernet circuit and ordinary SELV circuits that are user-contactable. This is because under 60950, Ethernet is classified as an SELV circuit. There are no requirements to separate one SELV circuit from another. Where this issue becomes confusing is that under the Ethernet 802.3 standard, an Ethernet port must provide a 1500 VRMS isolation barrier between the Ethernet conductors and earth. This is a legacy requirement whose origins seem to have been lost in the sands of time. However, I believe the consensus view is that the original intent of this requirement was to protect against ground loops and was not related to user safety. Nevertheless, the 802.3 isolation requirement has sometimes been treated as though it is a safety requirement. Note that the 802.3 requirement is for a simple dielectric test, with no reference to creepage, clearance, or distance through solid insulation. So, in principle, there are no safety isolation requirements for your application, since both of the proposed power supplies have a SELV output. This makes the entire device a SELV circuit (unless there are other ports on the device that are not SELV). Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) j
Re: [PSES] POE creepage clearances
The external DC power supply needs to be SELV too, not just energy limited. ___ Ralph McDiarmid | Schneider Electric | Solar Business | CANADA | Regulatory Compliance Engineering From: Ron Pickard rpick...@equinoxpayments.com To: EMC-PSTC@LISTSERV.IEEE.ORG, Date: 11/26/2012 12:38 PM Subject: Re: [PSES] POE creepage clearances Hi Joe, I agree that an Ethernet circuit would be considered to be an SELV circuit and that would be true if the POE circuit were completely on premise generally, which would categorize this as a Class III product according to IEC/UL 60950-1 2nd Ed. given that the external power supply is a limited power source (LPS). However, TNV-1 creepage/clearance requirements would apply if the POE were to be exposed to overvoltages from telecommunication networks (essentially off premise) requiring Basic insulation. I make this distinction as Ian did not mention where the POE circuit originates. Best regards, Ron From: Joe Randolph [mailto:j...@randolph-telecom.com] Sent: Monday, November 26, 2012 12:43 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] POE creepage clearances Hi Ian: I think the short answer to your question is that under 60950 there are no requirements for creepage and clearance distance between the Ethernet circuit and ordinary SELV circuits that are user-contactable. This is because under 60950, Ethernet is classified as an SELV circuit. There are no requirements to separate one SELV circuit from another. Where this issue becomes confusing is that under the Ethernet 802.3 standard, an Ethernet port must provide a 1500 VRMS isolation barrier between the Ethernet conductors and earth. This is a legacy requirement whose origins seem to have been lost in the sands of time. However, I believe the consensus view is that the original intent of this requirement was to protect against ground loops and was not related to user safety. Nevertheless, the 802.3 isolation requirement has sometimes been treated as though it is a safety requirement. Note that the 802.3 requirement is for a simple dielectric test, with no reference to creepage, clearance, or distance through solid insulation. So, in principle, there are no safety isolation requirements for your application, since both of the proposed power supplies have a SELV output. This makes the entire device a SELV circuit (unless there are other ports on the device that are not SELV). Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) j...@randolph-telecom.com http://www.randolph-telecom.com Dear colleagues We are developing a hand held product that is powered from +48V DC over Ethernet or from an external +12V DC wall wart PSU. The maximum internal voltage will be the +48V POE. Can anyone let me know what the creepage and clearance requirements between the ?primary? Ethernet circuit and the ?secondary? circuit. The product will be tested to IEC 60950 or possibly IEC 60065 so I am assuming a safety isolation creepage clearance is required. Many thanks in advance; Ian McBurney Design Engineer Allen Heath Ltd Kernick Industrial Estate Penryn, Cornwall TR10 9LU United Kingdom +44 (0)1326 370121 ian.mcbur...@dmh-global.com www.allen-heath.com A DMH Pro Company. - 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.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://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...@radiusnorth.net 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.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://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators
Re: [PSES] POE creepage clearances
Hi Ralph, Thanks for pointing that out, but I didn't think I had to mention that since Ian had already noted it being +12Vdc. Best regards, Ron From: ralph.mcdiar...@schneider-electric.com [mailto:ralph.mcdiar...@schneider-electric.com] Sent: Monday, November 26, 2012 5:22 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] POE creepage clearances The external DC power supply needs to be SELV too, not just energy limited. ___ Ralph McDiarmid | Schneider Electric | Solar Business | CANADA | Regulatory Compliance Engineering From: Ron Pickard rpick...@equinoxpayments.commailto:rpick...@equinoxpayments.com To: EMC-PSTC@LISTSERV.IEEE.ORGmailto:EMC-PSTC@LISTSERV.IEEE.ORG, Date: 11/26/2012 12:38 PM Subject: Re: [PSES] POE creepage clearances Hi Joe, I agree that an Ethernet circuit would be considered to be an SELV circuit and that would be true if the POE circuit were completely on premise generally, which would categorize this as a Class III product according to IEC/UL 60950-1 2nd Ed. given that the external power supply is a limited power source (LPS). However, TNV-1 creepage/clearance requirements would apply if the POE were to be exposed to overvoltages from telecommunication networks (essentially off premise) requiring Basic insulation. I make this distinction as Ian did not mention where the POE circuit originates. Best regards, Ron From: Joe Randolph [mailto:j...@randolph-telecom.com] Sent: Monday, November 26, 2012 12:43 PM To: EMC-PSTC@LISTSERV.IEEE.ORGmailto:EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] POE creepage clearances Hi Ian: I think the short answer to your question is that under 60950 there are no requirements for creepage and clearance distance between the Ethernet circuit and ordinary SELV circuits that are user-contactable. This is because under 60950, Ethernet is classified as an SELV circuit. There are no requirements to separate one SELV circuit from another. Where this issue becomes confusing is that under the Ethernet 802.3 standard, an Ethernet port must provide a 1500 VRMS isolation barrier between the Ethernet conductors and earth. This is a legacy requirement whose origins seem to have been lost in the sands of time. However, I believe the consensus view is that the original intent of this requirement was to protect against ground loops and was not related to user safety. Nevertheless, the 802.3 isolation requirement has sometimes been treated as though it is a safety requirement. Note that the 802.3 requirement is for a simple dielectric test, with no reference to creepage, clearance, or distance through solid insulation. So, in principle, there are no safety isolation requirements for your application, since both of the proposed power supplies have a SELV output. This makes the entire device a SELV circuit (unless there are other ports on the device that are not SELV). Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) j...@randolph-telecom.commailto:j...@randolph-telecom.com http://www.randolph-telecom.comhttp://www.randolph-telecom.com/ Dear colleagues We are developing a hand held product that is powered from +48V DC over Ethernet or from an external +12V DC wall wart PSU. The maximum internal voltage will be the +48V POE. Can anyone let me know what the creepage and clearance requirements between the ?primary? Ethernet circuit and the ?secondary? circuit. The product will be tested to IEC 60950 or possibly IEC 60065 so I am assuming a safety isolation creepage clearance is required. Many thanks in advance; Ian McBurney Design Engineer Allen Heath Ltd Kernick Industrial Estate Penryn, Cornwall TR10 9LU United Kingdom +44 (0)1326 370121 ian.mcbur...@dmh-global.commailto:ian.mcbur...@dmh-global.com www.allen-heath.comhttp://www.allen-heath.com/ A DMH Pro Companyhttp://www.dmh-global.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.orgmailto: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://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...@radiusnorth.netmailto:emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.orgmailto:mcantw...@ieee.org For policy questions, send mail to: Jim Bacher j.bac...@ieee.orgmailto:j.bac...@ieee.org David Heald
Re: [PSES] POE creepage clearances
SELV is 60 vdc but not if outdoor or wet environment - right ??? Then it drops to 30 vdc? So Ethernet is inside only for easy compliance ?? Maybe one can extend the inside environment to an outside application by careful use and implementation of conduit and enclosures... We get lazy and apply the creepage and clearance and keep moving. ps. I am not a safety engineer and have no clue... I suspect that the 1500 v isolation came from a single fault introduced at the PoE injector that tied primary to secondary and thus the PoE device needed to also have the isolation to withstand that fault. Add up how many isolation transformers are in the circuits back to primary and/or TNV-1. From: ralph.mcdiar...@schneider-electric.com ralph.mcdiar...@schneider-electric.com To: EMC-PSTC@LISTSERV.IEEE.ORG Sent: Monday, November 26, 2012 7:21 PM Subject: Re: [PSES] POE creepage clearances The external DC power supply needs to be SELV too, not just energy limited. ___ Ralph McDiarmid | Schneider Electric | Solar Business | CANADA | Regulatory Compliance Engineering From: Ron Pickard rpick...@equinoxpayments.com To: EMC-PSTC@LISTSERV.IEEE.ORG, Date: 11/26/2012 12:38 PM Subject: Re: [PSES] POE creepage clearances Hi Joe, I agree that an Ethernet circuit would be considered to be an SELV circuit and that would be true if the POE circuit were completely on premise generally, which would categorize this as a Class III product according to IEC/UL 60950-1 2nd Ed. given that the external power supply is a limited power source (LPS). However, TNV-1 creepage/clearance requirements would apply if the POE were to be exposed to overvoltages from telecommunication networks (essentially off premise) requiring Basic insulation. I make this distinction as Ian did not mention where the POE circuit originates. Best regards, Ron From: Joe Randolph [mailto:j...@randolph-telecom.com] Sent: Monday, November 26, 2012 12:43 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] POE creepage clearances Hi Ian: I think the short answer to your question is that under 60950 there are no requirements for creepage and clearance distance between the Ethernet circuit and ordinary SELV circuits that are user-contactable. This is because under 60950, Ethernet is classified as an SELV circuit. There are no requirements to separate one SELV circuit from another. Where this issue becomes confusing is that under the Ethernet 802.3 standard, an Ethernet port must provide a 1500 VRMS isolation barrier between the Ethernet conductors and earth. This is a legacy requirement whose origins seem to have been lost in the sands of time. However, I believe the consensus view is that the original intent of this requirement was to protect against ground loops and was not related to user safety. Nevertheless, the 802.3 isolation requirement has sometimes been treated as though it is a safety requirement. Note that the 802.3 requirement is for a simple dielectric test, with no reference to creepage, clearance, or distance through solid insulation. So, in principle, there are no safety isolation requirements for your application, since both of the proposed power supplies have a SELV output. This makes the entire device a SELV circuit (unless there are other ports on the device that are not SELV). Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) j...@randolph-telecom.com http://www.randolph-telecom.com Dear colleagues We are developing a hand held product that is powered from +48V DC over Ethernet or from an external +12V DC wall wart PSU. The maximum internal voltage will be the +48V POE. Can anyone let me know what the creepage and clearance requirements between the ?primary? Ethernet circuit and the ?secondary? circuit. The product will be tested to IEC 60950 or possibly IEC 60065 so I am assuming a safety isolation creepage clearance is required. Many thanks in advance; Ian McBurney Design Engineer Allen Heath Ltd Kernick Industrial Estate Penryn, Cornwall TR10 9LU United Kingdom +44 (0)1326 370121 ian.mcbur...@dmh-global.com www.allen-heath.com A DMH Pro Company. - 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.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://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org
Re: [PSES] POE creepage clearances
Gentlemen: Please recall that Ethernet is isolated from the sender/receiver circuits at each end of the Ethernet circuit (where the isolation in the equipment usually is a part of the Ethernet RJ45 connector). The isolation is 1500 V rms. Why? Because building transients magnetically couple into the Ethernet cable within the building wiring. Consider two buildings. The NEC requires the neutral to be grounded at each building service entrance. Therefore, the neutral is grounded at two points, which places the ground in parallel with the neutral, and, VOILA! the ground between the two buildings is a current-carrying conductor. Isolation from ground is required because, otherwise, the Ethernet conductors would be in parallel with the ground and would become a third current carrying conductor between the two buildings. And would quickly open due to the current. As I understand POE... http://hw-server.com/images/supply_diagram.png POE is a common-mode circuit between two Ethernet pair conductors. As shown in the diagram, the powered device must have a DC-DC converter which is isolated from ground (again, 1500 V RMS). http://www.poweroverethernet.com/associated/files/file_334_1114621476.pdf POE is a maximum 48 V DC. This circuit comprises SELV between poles, and a Limited Current Circuit between each pole and ground. The Ethernet standards require isolation between: (1) the Ethernet circuits and the internal equipment circuits (provided by the RJ45) and (2) the DC-DC converter input and output (provided by the equipment). However, 60950-1 does not require clearance or creepage across these isolations. Best regards, Rich -Original Message- From: Bill Owsley Sent: Monday, November 26, 2012 5:48 PM To: ralph.mcdiar...@schneider-electric.com ; EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] POE creepage clearances SELV is 60 vdc but not if outdoor or wet environment - right ??? Then it drops to 30 vdc? So Ethernet is inside only for easy compliance ?? Maybe one can extend the inside environment to an outside application by careful use and implementation of conduit and enclosures... We get lazy and apply the creepage and clearance and keep moving. ps. I am not a safety engineer and have no clue... I suspect that the 1500 v isolation came from a single fault introduced at the PoE injector that tied primary to secondary and thus the PoE device needed to also have the isolation to withstand that fault. Add up how many isolation transformers are in the circuits back to primary and/or TNV-1. From: ralph.mcdiar...@schneider-electric.com ralph.mcdiar...@schneider-electric.com To: EMC-PSTC@LISTSERV.IEEE.ORG Sent: Monday, November 26, 2012 7:21 PM Subject: Re: [PSES] POE creepage clearances The external DC power supply needs to be SELV too, not just energy limited. ___ Ralph McDiarmid | Schneider Electric | Solar Business | CANADA | Regulatory Compliance Engineering From: Ron Pickard rpick...@equinoxpayments.com To: EMC-PSTC@LISTSERV.IEEE.ORG, Date: 11/26/2012 12:38 PM Subject: Re: [PSES] POE creepage clearances Hi Joe, I agree that an Ethernet circuit would be considered to be an SELV circuit and that would be true if the POE circuit were completely on premise generally, which would categorize this as a Class III product according to IEC/UL 60950-1 2nd Ed. given that the external power supply is a limited power source (LPS). However, TNV-1 creepage/clearance requirements would apply if the POE were to be exposed to overvoltages from telecommunication networks (essentially off premise) requiring Basic insulation. I make this distinction as Ian did not mention where the POE circuit originates. Best regards, Ron From: Joe Randolph [mailto:j...@randolph-telecom.com] Sent: Monday, November 26, 2012 12:43 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] POE creepage clearances Hi Ian: I think the short answer to your question is that under 60950 there are no requirements for creepage and clearance distance between the Ethernet circuit and ordinary SELV circuits that are user-contactable. This is because under 60950, Ethernet is classified as an SELV circuit. There are no requirements to separate one SELV circuit from another. Where this issue becomes confusing is that under the Ethernet 802.3 standard, an Ethernet port must provide a 1500 VRMS isolation barrier between the Ethernet conductors and earth. This is a legacy requirement whose origins seem to have been lost in the sands of time. However, I believe the consensus view is that the original intent of this requirement was to protect against ground loops and was not related to user safety. Nevertheless, the 802.3 isolation requirement has sometimes been treated as though it is a safety requirement. Note that the 802.3 requirement is for a simple dielectric test, with no reference
[PSES] POE creepage clearances
Dear colleagues We are developing a hand held product that is powered from +48V DC over Ethernet or from an external +12V DC wall wart PSU. The maximum internal voltage will be the +48V POE. Can anyone let me know what the creepage and clearance requirements between the primary Ethernet circuit and the secondary circuit. The product will be tested to IEC 60950 or possibly IEC 60065 so I am assuming a safety isolation creepage clearance is required. Many thanks in advance; Ian McBurney Design Engineer Allen Heath Ltd Kernick Industrial Estate Penryn, Cornwall TR10 9LU United Kingdom +44 (0)1326 370121 ian.mcbur...@dmh-global.commailto:ian.mcbur...@dmh-global.com www.allen-heath.comhttp://www.allen-heath.com/ A DMH Pro Companyhttp://www.dmh-global.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.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://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...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] POE creepage clearances
In message 7b970d3d82cee74c920c2e6b0d3b837720be4...@sn2prd0610mb358.namprd06.prod.o utlook.com, dated Fri, 23 Nov 2012, Mcburney, Ian ian.mcbur...@dmh-global.com writes: We are developing a hand held product that is powered from +48V DC over Ethernet or from an external +12V DC wall wart PSU. The maximum internal voltage will be the +48V POE. Can anyone let me know what the creepage and clearance requirements between the ?primary? Ethernet circuit and the ?secondary? circuit. Insufficient data. Is the secondary circuit electrically accessible to the user? The product will be tested to IEC 60950 or possibly IEC 60065 so I am assuming a safety isolation creepage clearance is required. Do you not have those standards (60950-1 and 60065)? You should be looking at IEC 62368-1 as well for a new product development. -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk The longer it takes to make a point, the more obtuse it proves to be. 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 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://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...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] POE creepage clearances
Hello John; The front rear panel is painted metal. The base sides are a plastic moulding. So yes; the secondary circuit is electrically accessible to the user as the circuit board is mounted to the front panel using metal pillars. I have not started applying IEC 62368-1 as the testing agency I use has not recommend it. Is IEC 62368-1 the preferred option as opposed to IEC 60065 /60950 with most testing agencies now? Regards; Ian McBurney Design Engineer Allen Heath Ltd Kernick Industrial Estate Penryn, Cornwall TR10 9LU United Kingdom +44 (0)1326 370121 ian.mcbur...@dmh-global.com www.allen-heath.com A DMH Pro Company. -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of John Woodgate Sent: 23 November 2012 11:40 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: POE creepage clearances In message 7b970d3d82cee74c920c2e6b0d3b837720be4...@sn2prd0610mb358.namprd06.prod.o utlook.com, dated Fri, 23 Nov 2012, Mcburney, Ian ian.mcbur...@dmh-global.com writes: We are developing a hand held product that is powered from +48V DC over Ethernet or from an external +12V DC wall wart PSU. The maximum internal voltage will be the +48V POE. Can anyone let me know what the creepage and clearance requirements between the ?primary? Ethernet circuit and the ?secondary? circuit. Insufficient data. Is the secondary circuit electrically accessible to the user? The product will be tested to IEC 60950 or possibly IEC 60065 so I am assuming a safety isolation creepage clearance is required. Do you not have those standards (60950-1 and 60065)? You should be looking at IEC 62368-1 as well for a new product development. -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk The longer it takes to make a point, the more obtuse it proves to be. 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 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://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...@radiusnorth.net 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.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://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...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] POE creepage clearances
In message 7b970d3d82cee74c920c2e6b0d3b837720be5...@sn2prd0610mb358.namprd06.prod.o utlook.com, dated Fri, 23 Nov 2012, Mcburney, Ian ian.mcbur...@dmh-global.com writes: I have not started applying IEC 62368-1 as the testing agency I use has not recommend it. Is IEC 62368-1 the preferred option as opposed to IEC 60065 /60950 with most testing agencies now? For new designs, IEC/EN 62368-1 may come into mandatory effect before the end-of-life of your product. It is huge, and very different from the standards it will replace, so your designers and safety experts need to begin to get up to speed on it long before it becomes mandatory. I just don't understand how you can work without having copies of the standards you need to apply. There are now ways of getting them without paying hundreds of pounds but it isn't wise to discuss that too much on a public mailing list. -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk The longer it takes to make a point, the more obtuse it proves to be. 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 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://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...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
