On 4/27/2006, Grasso, Charles wrote:
Does anyone know of ( and hopefully access to) research that documents typical surge levels found on an AC mains distribution in a home as a result of lightning activity.?? I agree that C62.41 is a good place to get some basic information. In my experience, a surge withstand of 10 KV on the AC mains is needed to provide good reliability in the field. Similarly, a surge withstand on a phone line interface of about 5 KV is needed. However, that is not the whole story. Things get interesting if the product has multiple ports or there are multiple pieces of equipment connected by a LAN or USB. I have seen some unusual failure modes where a surge entered on the AC mains port and exited through the phone line, or where it entered on the phone line of a PC modem and then traveled on a USB cable to exit through another piece of equipment. Ironically, sometimes these alternative paths are facilitated by certain "protection" devices that had been installed on one or more ports. Lightning always seeks the lowest impedance path to earth, and sometimes the path it finds is not one that the designers anticipated. This is especially true if certain portions of the installation are intended to be grounded through a 3-wire AC mains plug that in some home installations may not actually be grounded. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) [email protected] http://www.randolph-telecom.com <http://www.randolph-telecom.com/> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] 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 [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
