Hi Amund:
There are two kinds of insulation: solid material and gas (air). (I am ignoring liquid insulation because it is seldom used in products that I have been associated with.) Creepage is the interface between solid insulation and air insulation. Creepage is NOT insulation. (Clearance is the minimum through-air insulation path.) Creepage is important because the solid insulation surface can be contaminated by a foreign material, thus reducing the electric strength of the solid insulation. (Creepage cannot – physically - be less than the associated clearance). The contamination (aka pollution) is subject to long-term heating by the rms value of the voltage through the pollution and the creepage path. The heating damages the solid insulation surface, reducing its electric strength. Hence, various standards specify creepage distances depending on pollution degree and comparative tracking index. Every solid insulation has an associated air insulation (e.g., for connection to the conductors). And, every air insulation has an associated solid insulation (e.g., to support the conductors). Consider a C14 appliance coupler. Or, an overhead power line. Clearance and creepage requirements do not apply to solid insulation. Well… creepage is the surface of solid insulation. Hope this helps, Rich From: Amund Westin <[email protected]> Sent: Tuesday, November 12, 2024 1:00 PM To: [email protected] Subject: [PSES] SV: [PSES] SV: [PSES] SV: [PSES] Creepage Live-Ground Hi Rich, Great summary. Through-holes is the case I’m struggling with now. 1. Through-holes. 1. Solid insulation between the AC plane and the through-hole conductor: No clearance and creepage requirements. 2. Solid insulation between the GND plane and the through-hole 230VACconductor: No clearance and creepage requirements. 3. Air insulation between the through-hole conductor and the AC plane: The separation must meet clearance and creepage requirements. 4. Air insulation between the through-hole 230VAC conductor and the GND plane: The separation must meet clearance and creepage requirements. I have added our situation and assume that doesn’t change the facts. Do I understand this correct, that all kind of clearance and creepage requirements are though air insulation, and not through solid pcb insulation? Where in IEC62368-1 (or IEC60950-1) will I find these paragraphs regarding “No clearance and creepage requirements”, as in the No.1 statement?. BR Amund On 2024-11-11 21:27, Richard Nute wrote: Hi Amund: 2. Plane separation. 1. No air insulation between planes: No clearance and creepage requirements: the planes can be adjacent. 2. Air insulation between planes: The planes must be separated by clearance and creepage requirements. 3. Edges of the PCB. 1. AC plane does not extend to the edge of the PCB: No clearance and creepage requirements. 2. AC plane extends to the edge of the PCB: Clearance and creepage dimensions are required. 4. Through-holes. 1. Solid insulation between the AC plane and the through-hole conductor: No clearance and creepage requirements. 2. Air insulation between the through-hole conductor and the AC plane: The separation must meet clearance and creepage requirements. 5. Solid-air series construction. 1. Such construction constitutes a capacitive voltage divider. Most of the voltage is across the air insulation. However, the solid insulation most likely has more than adequate electric strength. The air can be ignored. Best regards, Rich From: Amund Westin <mailto:[email protected]> <[email protected]> Sent: Monday, November 11, 2024 4:38 AM To: [email protected] <mailto:[email protected]> Subject: [PSES] SV: [PSES] SV: [PSES] Creepage Live-Ground In other words, is it allowed to have GND and LIVE in adjacent PCB layers? BR Amund Fra: Amund Westin Sendt: 11. november 2024 10:25 Til: [email protected] <mailto:[email protected]> Emne: [PSES] SV: [PSES] Creepage Live-Ground Ref. picture below … would the clearance be different in a case if we had a solid ground plane and solid LIVE AC plane on a PCB? Let’s say the planes were layer 2 and 3 in a 4-layer PCB. There must be some connection point to both layers, which could look like the picture below, but let’s say the there is a connection area on the PCB where the GND and LIVE are >> 20mm from each other. But the two layers are maybe 0.5mm from each other. BR Amund Fra: Amund Westin Sendt: 5. november 2024 14:51 Til: [email protected] <mailto:[email protected]> Emne: [PSES] Creepage Live-Ground Pin with 230VAC through the FR4 PCB with spacing to the inner ground plane. Creepage: Which table in the EN 62368-1:2020 apply? BR Amund _____ This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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To post a message to the list, send your e-mail to [email protected] <mailto:[email protected]> All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/[email protected]/ <https://www.mail-archive.com/[email protected]/%20> Website: https://ewh.ieee.org/soc/pses/ <https://ewh.ieee.org/soc/pses/> Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) <https://ewh.ieee.org/soc/pses/list.html> List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: [email protected] <mailto:[email protected]> Rick Linford at: [email protected] <mailto:[email protected]> For policy questions, send mail to: Jim Bacher at: [email protected] <mailto:[email protected]> _____ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC <https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1> &A=1 _____ This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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