10V/mil - so 60mil. 60 mil is ~1.5mm, if I am not mistaken. So you have a safety factor of ~2.5, based on the 0.5mm rating for 500V. Not the 10 fold increase that Inge recommended, but depending on your comfort level, may be OK. If this is on the primary side for a voltage entering a product, there may be CSA/UL type requirements to meet that may be different than the absolute minimums mentioned in the IPC document. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Nutting Sent: October 15, 2007 8:29 AM To: [log in to unmask] Subject: [TN] inner layer spacing for voltage Good morning, One of our engineers posed this question; " I have an inner ground plane in an area with high voltage (to 600 V). My question is this: What is the recommended spacing between the plated-though hole with this voltage and the internal ground plane relief outline? I will go with 10 V/mil as a default, but I am hoping the safe limit might be a bit higher than this." Can you point me to an IPC spec for this? I was thinking it might be in 2222. Thanks in advance. Phil --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------