I don't doubt that telephone equipment is sensitive to lightning-induced voltage spikes on power lines, WHEN the earth ground for the telephone line is physically separate from the ac neutral earth ground, as it can be according to older electrical codes (USA). This is the same problem that blows out TVs and VCRs, except there the ground separation is between ac neutral and the cable.
The important point is that it isn't the magnitude of the spike alone, but rather a differential potential induced across victim equipment with connections to two different potentials. Modern electrical codes provide single-point grounds which should totally mitigate this type of failure. Finally note that the failure mode here is not differential mode but common mode, spike arrestors if used need to connect between each power feeder, phone or cable line and green wire in order to be effective. ---------- >From: "Roman, Dan" <[email protected]> >To: "'George Stults'" <[email protected]>, [email protected] >Subject: RE: Voltage Spikes on Power Lines etc >Date: Thu, Mar 14, 2002, 2:04 PM > > > George, > > The ACTA for Part 68 has issued an advisory for Customer Information > documentation for Part 68 devices. It suggests a warning be included > suggesting the use of an AC surge arrestor. This is on page 7 of 8 of a PDF > file downloadable from http://www.part68.org/. > > It claims that telephone companies have reported that electrical surges are > very destructive to customer telephone equipment connected to AC power > sources. It also states that "This has been identified as a major > nationwide problem." > > A source for this information is not provided, but perhaps somewhere on the > web site you might find a contact that could point you to hard data. > > Dan > > -----Original Message----- > From: George Stults [mailto:[email protected]] > Sent: Thursday, March 14, 2002 12:17 PM > To: [email protected] > Subject: Voltage Spikes on Power Lines etc > > > > > Hi Folks, > > I am trying right now to convince some folks that power line voltage spike > problems can be and usually are severe enough to degrade or kill ITE > products that don't have adequate over-voltage protection. I found a link > using Google that describes the problems [ > http://www.kalglo.com/powrline.htm ] but I'm looking for additional links to > specifics or summaries if any one knows of such. > > Thanks in advance. > > George S. > > ------------------------------------------- > 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: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > 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" > > ------------------------------------------- > 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: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > 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" > ------------------------------------------- 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] 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"
