Re: [time-nuts] Thoughts on lightning protection measures....
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 1'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 -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ 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.
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 1'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.
Re: [time-nuts] Thoughts on lightning protection measures....
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 1'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.
Re: [time-nuts] Thoughts on lightning protection measures....
Chuck, You and Atilla must be right! when the basement for my home was dug I pounded in four standard eight foot plated ground rods horizontally just a few inches above the concrete footing which means they're down nearly six feet. I happen to respect a lot of the ideas of my maternal grandfather so I also have what might be called a classic lightning rod system with appropriate ground rods. While I do not claim to have some of the suggested elements of a ground field I do have more than 20 additional grounding points that accompany my ham radio antennas. And I learned about the wisdom of having home perimeter grounding too late to install that but all wiring in the house is metallic: EMT, greenfield or BX. So I think I have some elements of that as well. Anyway, while my neighbors, also living on the hill, have lost numerous TV sets, etc. I have never had a single loss to what I could plainly see was lightning. Even though a tree less than 30 feet from the house took a direct strike which killed the tree! Whenever the power company appears for whatever reason they always check my ground. They haven't complained yet! No, I'm no fool, when a storm is predicted or I hear the first faint thunder rumble all antennas and sensitive stuff power is disconnected. I've seen pieces of homes disappear when Old Mother Nature uses that particularly destructive tool of hers! Lee Mushel K9WRU - Original Message - From: Chuck Harris cfhar...@erols.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, April 13, 2012 7:14 AM Subject: Re: [time-nuts] Thoughts on lightning protection measures ___ 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.
Re: [time-nuts] Thoughts on lightning protection measures....
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 1'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.
Re: [time-nuts] Thoughts on lightning protection measures....
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 1'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.
[time-nuts] Thoughts on lightning protection measures....
Time-nutters-- Around here (N. Central Flori-DUH) it is not uncommon for near-by lightning strikes to damage underground cables and wiring. This is why buried wiring to things like driveway gate-openers are often placed in conduit rather than done with direct-burial wiring so that if lightning damages the wiring a new cable can be pulled through the conduit without having to re-dig the burial trench. Some years ago I had occasion to hold some long discussions with Martin Uman, one of the worlds most distinguished and eminent lightning researchers. He commented that even with the most extraordinary and costly efforts to install protection measures, that-- sooner or later-- there was a good chance that lightning would find a way to damage things. His lightning research laboratory was located here in N.Central Florida because it is in the heart of the most dense strike area in N. America. Mike Baker ___ 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.
Re: [time-nuts] Thoughts on lightning protection measures....
On 4/12/12 6:22 AM, Michael Baker wrote: Time-nutters-- Around here (N. Central Flori-DUH) it is not uncommon for near-by lightning strikes to damage underground cables and wiring. This is why buried wiring to things like driveway gate-openers are often placed in conduit rather than done with direct-burial wiring so that if lightning damages the wiring a new cable can be pulled through the conduit without having to re-dig the burial trench. Some years ago I had occasion to hold some long discussions with Martin Uman, one of the worlds most distinguished and eminent lightning researchers. He commented that even with the most extraordinary and costly efforts to install protection measures, that-- sooner or later-- there was a good chance that lightning would find a way to damage things. Dr. Uman (and his colleague Dr. Rakov) probably know about lightning and effects than any other humans alive. He's making an excellent point: at some point, the cost to replace the gear (or the cost of being off the air) is smaller than the cost of the protection scheme. Sometimes, you're better off having a sacrificial element, and a spare in the closet for speedy repair. His lightning research laboratory was located here in N.Central Florida because it is in the heart of the most dense strike area in N. America. ___ 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.
Re: [time-nuts] Thoughts on lightning protection measures....
True if you do not include the cost of the burned down house which is a possibility. Bert Kehren In a message dated 4/12/2012 9:59:08 A.M. Eastern Daylight Time, jim...@earthlink.net writes: On 4/12/12 6:22 AM, Michael Baker wrote: Time-nutters-- Around here (N. Central Flori-DUH) it is not uncommon for near-by lightning strikes to damage underground cables and wiring. This is why buried wiring to things like driveway gate-openers are often placed in conduit rather than done with direct-burial wiring so that if lightning damages the wiring a new cable can be pulled through the conduit without having to re-dig the burial trench. Some years ago I had occasion to hold some long discussions with Martin Uman, one of the worlds most distinguished and eminent lightning researchers. He commented that even with the most extraordinary and costly efforts to install protection measures, that-- sooner or later-- there was a good chance that lightning would find a way to damage things. Dr. Uman (and his colleague Dr. Rakov) probably know about lightning and effects than any other humans alive. He's making an excellent point: at some point, the cost to replace the gear (or the cost of being off the air) is smaller than the cost of the protection scheme. Sometimes, you're better off having a sacrificial element, and a spare in the closet for speedy repair. His lightning research laboratory was located here in N.Central Florida because it is in the heart of the most dense strike area in N. America. ___ 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.
Re: [time-nuts] Thoughts on lightning protection measures....
I have 2 TBolts but now I'm thinking to buy others to save them from the sacrifice... On Thu, Apr 12, 2012 at 3:58 PM, Jim Lux jim...@earthlink.net wrote: On 4/12/12 6:22 AM, Michael Baker wrote: Time-nutters-- Around here (N. Central Flori-DUH) it is not uncommon for near-by lightning strikes to damage underground cables and wiring. This is why buried wiring to things like driveway gate-openers are often placed in conduit rather than done with direct-burial wiring so that if lightning damages the wiring a new cable can be pulled through the conduit without having to re-dig the burial trench. Some years ago I had occasion to hold some long discussions with Martin Uman, one of the worlds most distinguished and eminent lightning researchers. He commented that even with the most extraordinary and costly efforts to install protection measures, that-- sooner or later-- there was a good chance that lightning would find a way to damage things. Dr. Uman (and his colleague Dr. Rakov) probably know about lightning and effects than any other humans alive. He's making an excellent point: at some point, the cost to replace the gear (or the cost of being off the air) is smaller than the cost of the protection scheme. Sometimes, you're better off having a sacrificial element, and a spare in the closet for speedy repair. His lightning research laboratory was located here in N.Central Florida because it is in the heart of the most dense strike area in N. America. ___ 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.
Re: [time-nuts] Thoughts on lightning protection measures....
Hi Is your house hit multiple times per year now? If so, I'd suggest that's the issue that needs to be solved. If not, then mount the antenna lower than the peak of the house and move on. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Azelio Boriani Sent: Thursday, April 12, 2012 10:04 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Thoughts on lightning protection measures I have 2 TBolts but now I'm thinking to buy others to save them from the sacrifice... On Thu, Apr 12, 2012 at 3:58 PM, Jim Lux jim...@earthlink.net wrote: On 4/12/12 6:22 AM, Michael Baker wrote: Time-nutters-- Around here (N. Central Flori-DUH) it is not uncommon for near-by lightning strikes to damage underground cables and wiring. This is why buried wiring to things like driveway gate-openers are often placed in conduit rather than done with direct-burial wiring so that if lightning damages the wiring a new cable can be pulled through the conduit without having to re-dig the burial trench. Some years ago I had occasion to hold some long discussions with Martin Uman, one of the worlds most distinguished and eminent lightning researchers. He commented that even with the most extraordinary and costly efforts to install protection measures, that-- sooner or later-- there was a good chance that lightning would find a way to damage things. Dr. Uman (and his colleague Dr. Rakov) probably know about lightning and effects than any other humans alive. He's making an excellent point: at some point, the cost to replace the gear (or the cost of being off the air) is smaller than the cost of the protection scheme. Sometimes, you're better off having a sacrificial element, and a spare in the closet for speedy repair. His lightning research laboratory was located here in N.Central Florida because it is in the heart of the most dense strike area in N. America. ___ 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.
Re: [time-nuts] Thoughts on lightning protection measures....
Only if it's not part of the sacrificial ritual... On the more serious part, while the lightning processes, and effects are scientifically researched for ages, an efficient lighting protection still borders black magic. On 4/12/2012 5:01 PM, ewkeh...@aol.com wrote: True if you do not include the cost of the burned down house which is a possibility. Bert Kehren In a message dated 4/12/2012 9:59:08 A.M. Eastern Daylight Time, jim...@earthlink.net writes: On 4/12/12 6:22 AM, Michael Baker wrote: Time-nutters-- Around here (N. Central Flori-DUH) it is not uncommon for near-by lightning strikes to damage underground cables and wiring. This is why buried wiring to things like driveway gate-openers are often placed in conduit rather than done with direct-burial wiring so that if lightning damages the wiring a new cable can be pulled through the conduit without having to re-dig the burial trench. Some years ago I had occasion to hold some long discussions with Martin Uman, one of the worlds most distinguished and eminent lightning researchers. He commented that even with the most extraordinary and costly efforts to install protection measures, that-- sooner or later-- there was a good chance that lightning would find a way to damage things. Dr. Uman (and his colleague Dr. Rakov) probably know about lightning and effects than any other humans alive. He's making an excellent point: at some point, the cost to replace the gear (or the cost of being off the air) is smaller than the cost of the protection scheme. Sometimes, you're better off having a sacrificial element, and a spare in the closet for speedy repair. His lightning research laboratory was located here in N.Central Florida because it is in the heart of the most dense strike area in N. America. ___ 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.
Re: [time-nuts] Thoughts on lightning protection measures....
A very efficient solution would be to get the signal/power conducting cables out of the lightning path - that means a GPS receiver near the antenna, with a local power supply (photo cell panels / buffer accumulator) and signal transmission over optical fiber. Quite feasible, as a GPS Rx has low power requirements. If the delay from receiver to the disciplined oscillator is critical, or too high, a compensation scheme comes to mind - 2 identical optical paths in a loop, with the sent pps signal phase adjusted so that the received GPS pps is centered between the sent and the looped one. Regarding the TBs, even if they are the only ones directly connected to the antenna, the cable is already punching through the house Faraday cage, and chances are quite high that the lightning discharge won't stop at them. On 4/12/2012 5:03 PM, Azelio Boriani wrote: I have 2 TBolts but now I'm thinking to buy others to save them from the sacrifice... On Thu, Apr 12, 2012 at 3:58 PM, Jim Luxjim...@earthlink.net wrote: On 4/12/12 6:22 AM, Michael Baker wrote: Time-nutters-- Around here (N. Central Flori-DUH) it is not uncommon for near-by lightning strikes to damage underground cables and wiring. This is why buried wiring to things like driveway gate-openers are often placed in conduit rather than done with direct-burial wiring so that if lightning damages the wiring a new cable can be pulled through the conduit without having to re-dig the burial trench. Some years ago I had occasion to hold some long discussions with Martin Uman, one of the worlds most distinguished and eminent lightning researchers. He commented that even with the most extraordinary and costly efforts to install protection measures, that-- sooner or later-- there was a good chance that lightning would find a way to damage things. Dr. Uman (and his colleague Dr. Rakov) probably know about lightning and effects than any other humans alive. He's making an excellent point: at some point, the cost to replace the gear (or the cost of being off the air) is smaller than the cost of the protection scheme. Sometimes, you're better off having a sacrificial element, and a spare in the closet for speedy repair. His lightning research laboratory was located here in N.Central Florida because it is in the heart of the most dense strike area in N. America. ___ 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.
Re: [time-nuts] Thoughts on lightning protection measures....
On Thu, 12 Apr 2012 17:39:57 +0300 MailLists li...@medesign.ro wrote: Regarding the TBs, even if they are the only ones directly connected to the antenna, the cable is already punching through the house Faraday cage, and chances are quite high that the lightning discharge won't stop at them. A house isnt a faraday cage. Not by far. Unless you live in a box made out of solid 5mm steal plates. If a lightning hits your house directly and is going down the lightning rod down into earth there is a good chance that the electric and magnetic fields you have in the house will fry sensitive electronic equipment Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ 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.
Re: [time-nuts] Thoughts on lightning protection measures....
You're right, but it's highly depending on the used construction materials... The building I live in, is quite like a Faraday cage - reinforced concrete. Even higher frequency radio signals have a tough time entering, mostly through the windows. What I wanted to underline is that, even if the house would be build like a Faraday cage, any conductor from the outside represents a potential dangerous ingress path. Of course, the generated fields would affect any sensitive equipment, but with the low impedance path of an antenna cable, even the less sensitive ones could suffer catastrophic failure. Not to neglect are all the other conductors entering from the outside - power lines, metallic pipes, etc. Full protection is quite difficult, almost impossible, to obtain, but an antenna cable is the preferred path. On 4/12/2012 6:02 PM, Attila Kinali wrote: On Thu, 12 Apr 2012 17:39:57 +0300 MailListsli...@medesign.ro wrote: Regarding the TBs, even if they are the only ones directly connected to the antenna, the cable is already punching through the house Faraday cage, and chances are quite high that the lightning discharge won't stop at them. A house isnt a faraday cage. Not by far. Unless you live in a box made out of solid 5mm steal plates. If a lightning hits your house directly and is going down the lightning rod down into earth there is a good chance that the electric and magnetic fields you have in the house will fry sensitive electronic equipment 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.
Re: [time-nuts] Thoughts on lightning protection measures....
One interesting fact: frozen ground is a bad conductor. The ground potential around your house may go up many 1000s of volts even with just a proximity strike, while the power feed stays down, blowing up anything connected to ground. Thus the special Nordig surge protection requirements for TV receivers in northern European countries.. On Apr 12, 2012, at 6:58, Jim Lux jim...@earthlink.net wrote: On 4/12/12 6:22 AM, Michael Baker wrote: Time-nutters-- Around here (N. Central Flori-DUH) it is not uncommon for near-by lightning strikes to damage underground cables and wiring. This is why buried wiring to things like driveway gate-openers are often placed in conduit rather than done with direct-burial wiring so that if lightning damages the wiring a new cable can be pulled through the conduit without having to re-dig the burial trench. Some years ago I had occasion to hold some long discussions with Martin Uman, one of the worlds most distinguished and eminent lightning researchers. He commented that even with the most extraordinary and costly efforts to install protection measures, that-- sooner or later-- there was a good chance that lightning would find a way to damage things. Dr. Uman (and his colleague Dr. Rakov) probably know about lightning and effects than any other humans alive. He's making an excellent point: at some point, the cost to replace the gear (or the cost of being off the air) is smaller than the cost of the protection scheme. Sometimes, you're better off having a sacrificial element, and a spare in the closet for speedy repair. His lightning research laboratory was located here in N.Central Florida because it is in the heart of the most dense strike area in N. America. ___ 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.
Re: [time-nuts] Thoughts on lightning protection measures....
Hi The lightning hit is both a great big voltage and a wallop of current. The voltage is the thing many people get worried about. Almost all of the damage I've had has come from current induced into near by conductors and similar magnetic field issues. That said, the voltage spike has likely jumped several hundred feet to get into the vicinity of your house. Hopping from this to that while trying to run through the house is trivial compared to the distance it's already traveled. There are indeed ways to take care of this stuff. Some systems are set up for a how many strikes per hour type of operation. They do indeed run properly in a high hit rate environment. You do *not* want to foot the cost for an installation like that. Having the (insured) house burn down is much cheaper Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of MailLists Sent: Thursday, April 12, 2012 11:22 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Thoughts on lightning protection measures You're right, but it's highly depending on the used construction materials... The building I live in, is quite like a Faraday cage - reinforced concrete. Even higher frequency radio signals have a tough time entering, mostly through the windows. What I wanted to underline is that, even if the house would be build like a Faraday cage, any conductor from the outside represents a potential dangerous ingress path. Of course, the generated fields would affect any sensitive equipment, but with the low impedance path of an antenna cable, even the less sensitive ones could suffer catastrophic failure. Not to neglect are all the other conductors entering from the outside - power lines, metallic pipes, etc. Full protection is quite difficult, almost impossible, to obtain, but an antenna cable is the preferred path. On 4/12/2012 6:02 PM, Attila Kinali wrote: On Thu, 12 Apr 2012 17:39:57 +0300 MailListsli...@medesign.ro wrote: Regarding the TBs, even if they are the only ones directly connected to the antenna, the cable is already punching through the house Faraday cage, and chances are quite high that the lightning discharge won't stop at them. A house isnt a faraday cage. Not by far. Unless you live in a box made out of solid 5mm steal plates. If a lightning hits your house directly and is going down the lightning rod down into earth there is a good chance that the electric and magnetic fields you have in the house will fry sensitive electronic equipment 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.
Re: [time-nuts] Thoughts on lightning protection measures....
On Thu, 12 Apr 2012 09:20:37 -0700 Said Jackson saidj...@aol.com wrote: One interesting fact: frozen ground is a bad conductor. The ground potential around your house may go up many 1000s of volts even with just a proximity strike, while the power feed stays down, blowing up anything connected to ground. Thus the special Nordig surge protection requirements for TV receivers in northern European countries.. Hmm? That sounds interesting. In switzerland, and AFAIK in most european countries, power feeds have to be grounded at the entry of the house (ie the neutral conductor is grounded). This should protect the electrical equipment from such ground jumps as you discribe. Or do i miss something? Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ 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.
Re: [time-nuts] Thoughts on lightning protection measures....
Fortunately, it seems that lightning is not as frequent in high northern and southern latitudes as is in tropical regions. I was told about a story of a group of Swedish scientists involved in thunderstorm studies, having built a little lab in the village with the best reputation of high probability of lightning, receiving after several years without events a delegation of the residents very grateful because after the lab installation there was no more lightning. Best regards, Antonio CT1TE Em 2012-04-12 17:20, Said Jackson escreveu: One interesting fact: frozen ground is a bad conductor. The ground potential around your house may go up many 1000s of volts even with just a proximity strike, while the power feed stays down, blowing up anything connected to ground. Thus the special Nordig surge protection requirements for TV receivers in northern European countries.. On Apr 12, 2012, at 6:58, Jim Lux jim...@earthlink.net wrote: On 4/12/12 6:22 AM, Michael Baker wrote: Time-nutters-- Around here (N. Central Flori-DUH) it is not uncommon for near-by lightning strikes to damage underground cables and wiring. This is why buried wiring to things like driveway gate-openers are often placed in conduit rather than done with direct-burial wiring so that if lightning damages the wiring a new cable can be pulled through the conduit without having to re-dig the burial trench. Some years ago I had occasion to hold some long discussions with Martin Uman, one of the worlds most distinguished and eminent lightning researchers. He commented that even with the most extraordinary and costly efforts to install protection measures, that-- sooner or later-- there was a good chance that lightning would find a way to damage things. Dr. Uman (and his colleague Dr. Rakov) probably know about lightning and effects than any other humans alive. He's making an excellent point: at some point, the cost to replace the gear (or the cost of being off the air) is smaller than the cost of the protection scheme. Sometimes, you're better off having a sacrificial element, and a spare in the closet for speedy repair. His lightning research laboratory was located here in N.Central Florida because it is in the heart of the most dense strike area in N. America. ___ 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.
Re: [time-nuts] Thoughts on lightning protection measures....
On Thu, Apr 12, 2012 at 7:22 AM, Bob Camp li...@rtty.us wrote: Hi Is your house hit multiple times per year now? If so, I'd suggest that's the issue that needs to be solved. If not, then mount the antenna lower than the peak of the house and move on. Did you not read the first post in this thread? He said it is common to have buried cables dangaged by near by strikes. I assume under ground is not the tallest thing around The point about lightening is NOT if the object is directly struct. There is nothing you can do in that case, a ightening arrestor is kind of a joke to a bolt that just jumped across a miles long air gap. What destroyed the underground cable is the EMP pulse from a strike that was 100 feet away. EMP induced a current and the current was greater then the current carrying ability of the conductor. Chris Albertson Redondo Beach, California ___ 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.
Re: [time-nuts] Thoughts on lightning protection measures....
Hi Attila, 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. 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 1'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. 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) bye, Said In a message dated 4/12/2012 09:54:40 Pacific Daylight Time, att...@kinali.ch writes: Hmm? That sounds interesting. In switzerland, and AFAIK in most european countries, power feeds have to be grounded at the entry of the house (ie the neutral conductor is grounded). This should protect the electrical equipment from such ground jumps as you discribe. Or do i miss something? 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.
Re: [time-nuts] Thoughts on lightning protection measures....
Said, The ground is a decent thermal isolator. And will in nordic countries not often go deeper than about 1 meter. You need to build your houses foundation deep enough to stand on non frozen ground. Otherwise your house will move to much with the seasons and likely break. It is not that hard to get your ground pole deep enough to avoid freezing problems. -- Björn Hi Attila, 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. 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 1'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. 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) bye, Said In a message dated 4/12/2012 09:54:40 Pacific Daylight Time, att...@kinali.ch writes: Hmm? That sounds interesting. In switzerland, and AFAIK in most european countries, power feeds have to be grounded at the entry of the house (ie the neutral conductor is grounded). This should protect the electrical equipment from such ground jumps as you discribe. Or do i miss something? 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.
Re: [time-nuts] Thoughts on lightning protection measures....
Hi Bjoern, Possibly, I am just reciting what I read in the Nordig requirements a looong time ago. Maybe they are worried about far north permafrost scenarios that go deeper? The requirements for receiver RF input surge protection were much higher than the usual US requirements.. bye, Said In a message dated 4/12/2012 15:38:55 Pacific Daylight Time, b...@lysator.liu.se writes: Said, The ground is a decent thermal isolator. And will in nordic countries not often go deeper than about 1 meter. You need to build your houses foundation deep enough to stand on non frozen ground. Otherwise your house will move to much with the seasons and likely break. It is not that hard to get your ground pole deep enough to avoid freezing problems. -- Björn ___ 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.
