Hello Brian, I've employed spark gaps, like you, not because you 'have' to but because it seemed good practice. It involved a control installation with cables strung externally.
My advice is to use propriatory discharge tubes. They're cheap and their performance is more predictable than engineering your own air gap across PCB tracks or using pointy pins and are much less influenced physical and environmental conditions such as temperature and humidity, etc. And should they ever be needed, the consequences can be much less messy. I found a good selection available and looked at PCB mounting tubes with breakdown voltages of between 3 and 12 kV. I finally used 4kV, 5kA/10kA (10/1 discharges) devices having been influenced by what professional LAN & GPS installers were using which largely ranged between 3 and 6 kV. Just my thoughts. T ----- Original Message ----- From: Kunde, Brian Sent: 09/06/13 04:56 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Spark Gap PCB Layout on AC Mains Our engineers are working on an AC Mains Distribution PCB. Like most electronic devices, we have seen the damage caused by lightning strikes. So we are increasing our creepage and clearance distances as wide as we can and still meet other requirements. But no matter what spacing you design to, there is a lightning bolt out there that will exceed the design and it will arc somewhere. So the question came up to whether it makes sense to deliberately make a weak spot, or an area where the clearance is slightly smaller to control where a lightning/surge pulse will arc and/or discharge, like a Spark-Gap. I have seen spark-gap lay outs on PC boards on I/O connectors; usually for ESD protection, but not on AC Mains. Is this a bad bad idea or something worth doing? Pros and Cons? Other suggestions?? Thanks to all for your help. The Other Brian ----------------------------------------------------------------- *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 < 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://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 <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>
