Amund, I believe that we agree in principle. I am not proposing that the test report include everything that is not covered (a tricky business) but, rather, that it include a simple statement such as: this product has been evaluated as a mains product throughout and the detailed review of the usual isolation/insulation has not been done. (I’m sure you could come up with more inclusive wording, but in the end, the reader is put on notice as to the restricted applicability of the evaluation.)
This is a good exercise in adapting the requirements of the standard to a specific application. I’m pleased that we examined this in this forum. :>) br, Pete Peter E Perkins, PE Principal Product Safety & Regulatory Affairs Consultant PO Box 1067 Albany, ORe 97321-0413 503/452-1201 IEEE Life Fellow IEEE PSES 2020 Distinguished Lecturer <http://www.researchgate.net/Peter%20Perkins> www.researchgate.net search my name <mailto:p.perk...@ieee.org> p.perk...@ieee.org Entropy ain’t what it used to be From: Amund Westin <am...@westin-emission.no> Sent: Tuesday, September 14, 2021 11:39 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] SV: [PSES] Creepage and clearance requirements Pete, I can follow your thoughts and that special things can happen with such a product in the long run. But the manufacturer will probably make designs that support product functionality and design as original intended. Taking into account future new development of HW and other functionalities will probably not be relevant due to, among other things, costs. But I recognize that increasing distances from 2mm to 6mm should not be cost driven. But if this is to be done after the product's first version is launched, then it will mean new pcb layouts and components with the costs that follow. It is not known whether UL or Nemko or other accredited test laboratories will point out in their test report that the design will not be approved if you later connect I / O lines to the secondary circuits on the product. If a new manufacturer or company were to introduce such product changes without making sure that they could reuse the design without having to make any changes to the original design, it must be said to be a strange approach. But if it is either written in test reports or in other documentation that safety only applies to products as it appears, then it is of course positive. Best regards Amund Fra: Pete Perkins Sendt: 14. september 2021 16:51 Til: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Emne: Re: [PSES] Creepage and clearance requirements Amund, I support Rich’s approach. It does leave a lingering question, though. (removing my rose colored glasses and putting on my dark, pessimistic glasses) Imagine a downstream case such as this: The unit works well and is popular. A customer request comes to the manufacturer something to the effect that the unit works well except does not provide the full operational reliability in cases where there is significant EMC generated in the use area; they ask for an output (USB , PoE, etc) so that they can cable connect the unit for these applications. A (different) company designer believes that this is easy to do and starts to work on this project. If you are lucky, he consults the earlier safety lab report to understand the details to properly implement this. Where in the report do you clearly state that the requirements, including isolation/insulation (creepage and clearance) were not evaluated and the ‘secondary’ is considered mains in a clear way? With this understanding the designer will know that the full mains isolation/insulation will have to be done for the output circuit since it wasn’t done for the mains/secondary interface initially. (Since, reasonably often, the unit won’t meet the mains/secondary requirements in some way and the manufacturer will not be willing to change it in this redesign cycle.) If this is not clearly taken care of initially then the process starts down the slippery slope of believing that everything was completed earlier and not fully reviewed at the modification step. If not caught by the designer then the test lab catch will be a major complication in the project schedule. If not caught by the test lab (your associate down the hall) then the product is inadequate and does not meet the requirements of the standard; hopefully this gets caught in the review but what if it doesn’t? My point is that simplifications need to be clearly stated in the documentation for downstream users. Don’t leave anything to chance. :>) br, Pete Peter E Perkins, PE Principal Product Safety & Regulatory Affairs Consultant PO Box 1067 Albany, ORe 97321-0413 503/452-1201 IEEE Life Fellow IEEE PSES 2020 Distinguished Lecturer <http://www.researchgate.net/Peter%20Perkins> www.researchgate.net search my name <mailto:p.perk...@ieee.org> p.perk...@ieee.org Entropy ain’t what it used to be From: Richard Nute <ri...@ieee.org <mailto:ri...@ieee.org> > Sent: Sunday, September 12, 2021 3:05 PM To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] Creepage and clearance requirements Hi Amund: If no accessible conductive parts, then you can designate the secondary circuits as part of the primary circuits, which means there is no need for isolation between primary and secondary circuits. No creepage or clearance requirements! OVC would not apply primary-to-(a primary) secondary. The plastic enclosure would probably constitute reinforced insulation throughout. For electric shock, you would wrap in foil and measure touch current. Should be comfortably below the limit. And, you would need to do a dielectric test to the same foil at twice the voltage necessary for basic insulation. Should easily pass. I have assumed the antenna is within the enclosure so no accessible conductive parts. If the antenna is an accessible conductive part, then the above scenario is not valid. Stay safe, and best regards, Rich From: Amund Westin <am...@westin-emission.no <mailto:am...@westin-emission.no> > Sent: Sunday, September 12, 2021 10:16 AM To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> Subject: [PSES] Creepage and clearance requirements IEC60950-1: How about the Creepage and clearance requirements for an AC driven radio HUB device. * One input: 230VAC (direct into wall socket) * No physical output ports, just radio communication. * Insulated plastic enclosure (UL94 V-0) The Creepage and clearance requirements between primary and secondary circuits, does it make any sense as long as the device has no cables and is encapsulated by a plastic enclosure I understand that there should be some Creepage and clearance to withstand OVC II (250V transient). Best regards Amund - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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