Hi The process of bonding everything together is a lot easier if the house is set up with all the "stuff" coming in at one point. If phone, water, power, and cable all come in on their own corner - not quite so easy.
Bob On Apr 13, 2012, at 5:34 PM, Chuck Harris wrote: > Hi Bob, > > When I had my lightning protection survey done on my house, > there was a requirement that all of the lightning grounds > be tied to the power, telephone, cable, and water grounds > at a single point. Before I did this, I lost modems, network > cards, fax machines, etc.. afterward, no problems. > > I do lose the occasional phone surge protector in the network > interface block, but they seem to do their job, and protect > everything else. > > -Chuck Harris (knocking on wood!) > > Bob Camp wrote: >> Hi >> >> Yes indeed, very true. >> >> Things like telephone lines and cable lines need to "jump" at the same time >> as the house ground. The fact that they don't is what makes cordless phone >> base stations, modems (remember them?) and cable boxes the main victims in >> lightning hits. >> >> Bob >> >> -----Original Message----- >> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On >> Behalf Of Chuck Harris >> Sent: Friday, April 13, 2012 9:14 AM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] Thoughts on lightning protection measures.... >> >> As the power line worker strapped to the million volt wires he is >> working on shows, what is important is that all the grounds in the >> house stay at the same potential... not that they stay at some >> perfect earth ground potential. >> >> It really doesn't matter if a "house" ground jumps up many >> thousands of volts for an instant during a lightning strike, as >> long as everything electronic in the house, and everything >> structural in the house jumps too. >> >> -Chuck Harris >> >> >> Attila Kinali wrote: >>> Moin, >>> >>> On Thu, 12 Apr 2012 18:28:24 -0400 (EDT) >>> saidj...@aol.com wrote: >>> >>>> if I remember correctly, the issue is that the "ground" at the house is >>>> not a "real" ground when the earth is frozen, as the resistance of frozen >>>> earth goes up substantially over non-frozen earth. So it's like not >> having >>>> grounded the wires at all. >>> >>> Yes, that's why in Switzerland you have to bury the grounding loop/wires >>> at least 1m deep (IIRC), in cold areas even 1.5m deep(again IIRC) to >> ensure >>> that the earth never freezes. >>> >>> I would have assumed that the building rules in the north have similar >>> requirements, just with deeper digging. >>> >>> Of course, if you live on permafrost, you will never have a decent ground >> :-) >>> >>>> This is a real issue for cables brought to the house (cable TV, >> telephone, >>>> etc etc) as those cables are grounded somewhere else on the other side, >> and >>>> thus there may be 1000's or even 10000's Volts between the two >> "grounds", >>>> even (or especially) for just a proximity strike. As mentioned by >> someone >>>> else, all bets are off anyway's for direct hits, not much will survive a >>>> direct hit. >>> >>> Well.. if you have a near hit on some long cable. you're lucky if the >>> attached electronics survive. But it shouldn't kill everything in the >>> house. My point was that, with "proper" ground connection, your house >>> potential should increase to "many 1000s of volt", even with a near hit. >>> Again, i might miss there something. >>> >>>> >>>> It's been a long time since I designed cable TV receivers, but the specs >>>> are here, and I think there are some explanations in there somewhere: >>>> >>>> _http://www.nordig.org/specifications.htm_ >>>> (http://www.nordig.org/specifications.htm) >>> >>> Thanks, i'll have a look at those. >>> >>> Attila Kinali >>> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.