In message <001701c86c28$3ff658e0$c700a8c0@PC323541548743>, dated Sun, 10 Feb 2008, [email protected] writes:
> > > > >> >An electrical forensic engineer, Ed Clark, has >> >presented a theory of how power lines could have >> >started one or more of last October's San Diego >> >fires. He blames it on loose connections in >> >the power pole support cables. His evidence is >> >compelling. >> >> I'd like to see some numbers, voltage induced in the guy-ground-guy >> triangle by plausible currents in the 69 kV line, and consequent >> current. > >So would I. > A very rough calculation suggests that 100 A in the line (assumed single-phase) induces only about 20 millivolts in the triangle. If the line is 15 m above ground and carries 100 A, the flux density at ground level is 1.3 microtesla. While the flux density increases with height above ground, the width of the triangle decreases, so roughly compensates. The area of the triangle is about 43 square metres, and the frequency is 60 Hz, so, using V = 2*pi*f*B*A, V = 21.2 mV. YVMD! -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk For very important information, please turn over. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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
