Hello Michael-- I believe you can find the resistivity of earth as a functions of terrain (single or mixed types of soil), moisture content, salt content, and even temperature in: Chapter 2, section 2.7 (PP 2.36 through 2.41) of Grounding and Bonding, Volume 2 of an 12 volume EMC series published by ICT (now defunct). The author is Michel Mardiguian, the ISBN is 0-944916-02-3. The book is out of print and Amazon doesn't show alternate sources. Hopefully your technical library can get a copy of the book or of the selected pages. Contact me at my email address if you need more help. Regards, Thurman J. (Bill) Ritenour EMC Compliance LLC Boulder, CO 80303 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu