Sam - Your post was no doubt sent before I replied to John Allen. FWIW, I'll try to add some clarity on the power cross testing.
The power lines that are collocated with telecommunication lines are typically medium voltage. There are both induced voltages into and metallic power cross to the telecommunication lines. The primary protector at a building entrance limits the voltages available to do harm to 600Vrms (assumed sinusoidal). There might also be secondary protection on telecommunication lines that include supplemental overvoltage protection that limits the voltage downstream to even lesser levels. The 120V and 240V power cross tests are to simulate someone digging and tearing through both a branch circuit and a telecommunication line in a stroke. While much of the telecommunications infrastructure is buried, I hesitate to say "most" is. In most new construction since ~1970, perhaps earlier, it is. It certainly isn't in my parents' neighborhood; or probably most older neighborhoods and business districts, especially those that are less wealthy than others. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA peter.tar...@sanmina-sci.com > From: Sam Davis > Sent: Thursday, December 12, 2002 7:56 AM > > In the US, aren't overhead power lines in the 10 > kV range? > > Anyway, my point here is that the power line > cross at the overhead poles > won't just put 120V on the phone lines, but 10kV, > likely incinerating the > line. I'm not sure where the power line cross > test is simulating, but it's > not at the overhead poles. > > Besides that, most telephone wiring is buried. > > Just my 2C, > Sam > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
