Re: [AMRadio] Somewhat Off topic - lightning protection
> Call your power company and ask for the sales department. The unit plugs > into the meter base and is grounded to the ground rod then there are surge > protectors in the house. If you don't have any luck, let me know and I will > call my REC and get the name and particulars on it. They're probably made by Joslyn, and are called "Lightning Arrestors". http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4675&item=5708676716&rd=1 Currently, 0 bids- starting at $9.oo *Pssst* less than 18 hours to go on this one... 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] Somewhat Off topic - lightning protection
The REC protector is probably available from any power company. Here in the Sulphur, OK area I am on an REC and called them about it when I first heard about the unit. They knew immediately and quoted 50 dollar installation + 5 bucks per month. They supply protection inside the house for 3 appliances for the 5 dollars per month and you can have them install more than that. I forget the exact details. I fooled around and haven't had it installed yet then the other day during a storm we had a hit very close to the house. I heard the sizzle and the crack of the bolt immediately. I am calling tomorrow for installation. I am worried because my house is built on fill dirt that is 24 inches above bedrock just like the telescope installation mentioned earlier. Call your power company and ask for the sales department. The unit plugs into the meter base and is grounded to the ground rod then there are surge protectors in the house. If you don't have any luck, let me know and I will call my REC and get the name and particulars on it. 73 Jim de W5JO - Original Message - From: "Patrick Jankowiak" <[EMAIL PROTECTED]> To: Sent: Tuesday, July 13, 2004 10:46 PM Subject: [AMRadio] Somewhat Off topic - lightning protection > Is your safety ground actually grounded (with a ground rod) at > the main box, and therein also securely bonded to the neutral > lead of the incoming utility power? with a #4 wire or better? > > This keeps the lightning voltage which is coming in from from the > ground, at or near the same potential as your neutral lead, > thereby minimizing the voltage between GND and NEUT during a > lightning strike. > > The REC's protector, is it something sold commercially? Sounds > interesting. > > Patrick > > > Date: Tue, 13 Jul 2004 18:18:49 -0500 > From: "Sara & Wayne Steiner" <[EMAIL PROTECTED]> > Subject: Re: [AMRadio] Somewhat Off topic - lightning protection > > > My semi rural home has all wiring , power, telephone and cable > all under ground. Over the years there have been several been > several cases where I have sustained damage caused by lighting > strikes in the area. None at the house. I purchased a surge > protector from the rural elec co-op which is guraranteed to work. > The last strike about 1200 ft away put a crater in the ground and > took out the surge protector which was furnished by the rural > electric co-op. They replaced the protector at no cost. I had > no damage. > > Before the REC protector, one of my cases of damage was the > refrigerator wiring harness. It was toast!. The high potential > seemed to come in through the safety ground! Didn't trip the > breaker! I have no explanation. The potential created by a > lighting strike induced into under ground wiring is > huge! Check with with your elec company for their surge > protectors, at least they may guaranty their product as mine does. > > ___ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio > >
[AMRadio] Somewhat Off topic - lightning protection
Is your safety ground actually grounded (with a ground rod) at the main box, and therein also securely bonded to the neutral lead of the incoming utility power? with a #4 wire or better? This keeps the lightning voltage which is coming in from from the ground, at or near the same potential as your neutral lead, thereby minimizing the voltage between GND and NEUT during a lightning strike. The REC's protector, is it something sold commercially? Sounds interesting. Patrick Date: Tue, 13 Jul 2004 18:18:49 -0500 From: "Sara & Wayne Steiner" <[EMAIL PROTECTED]> Subject: Re: [AMRadio] Somewhat Off topic - lightning protection My semi rural home has all wiring , power, telephone and cable all under ground. Over the years there have been several been several cases where I have sustained damage caused by lighting strikes in the area. None at the house. I purchased a surge protector from the rural elec co-op which is guraranteed to work. The last strike about 1200 ft away put a crater in the ground and took out the surge protector which was furnished by the rural electric co-op. They replaced the protector at no cost. I had no damage. Before the REC protector, one of my cases of damage was the refrigerator wiring harness. It was toast!. The high potential seemed to come in through the safety ground! Didn't trip the breaker! I have no explanation. The potential created by a lighting strike induced into under ground wiring is huge! Check with with your elec company for their surge protectors, at least they may guaranty their product as mine does.
Re: [AMRadio] Somewhat Off topic - lightning protection
Hi Brian My semi rural home has all wiring , power, telephone and cable all under ground. Over the years there have been several been several cases where I have sustained damage caused by lighting strikes in the area. None at the house. I purchased a surge protector from the rural elec co-op which is guraranteed to work. The last strike about 1200 ft away put a crater in the ground and took out the surge protector which was furnished by the rural electric co-op. They replaced the protector at no cost. I had no damage. Before the REC protector, one of my cases of damage was the refrigerator wiring harness. It was toast!. The high potential seemed to come in through the safety ground! Didn't trip the breaker! I have no explanation. The potential created by a lighting strike induced into under ground wiring is huge! Check with with your elec company for their surge protectors, at least they may guaranty their product as mine does. 73 Wayne, N0TE
Re: [AMRadio] Somewhat Off topic - lightning protection
In cases like this "ground potential" is a relative term due to ground currents. The resistance of the ground itself can cause large potential gradients over short distances. This is exactly why it's possible to get killed by lighting without being directly hit: the potential across the distance between your feet can be more than sufficient to generate a voltage that the soles of your shoes cannot withstand. Peak currents in a cloud-to-ground strike can be exceed 50 kA on a regular basis and it doesn't take much R to get a big E with that I. The currents involved are truly mind-boggling. The advice your brother got is essentially correct: a *very* conductive grid needs to be installed all around the protected site such that large currents will not induce large voltage gradients. Copper sulfate won't do. Experimental weather radars I've seen are protected against lightning with a 00 ga copper wire mesh within the ground (3-5' deep) with many ground rods, all bonded together using thermite. A very coarse heavy-wire grid above the radar dish elevation acts as pseudo Faraday cage. Everything needs to be bonded together and then bonded to this heavy ground to be protected. Lightning protection is an expensive proposition and has to be weighed against the potential losses, but a professional analysis and installation is probably the best way to go. Kim Elmore, N5OP At 11:29 AM 7/13/2004, you wrote: This is somewhat off-topic, however the issue of lightning protection is important, and knowing how knowledgeable our members are, I thought someone might have a solution to the following problem.. My brother has a very expensive telescope in an observatory located on Petit Jean Mtn. in Arkansas. His telescope has a computerized tracking and "GoTo" system built into the base of the mount which is mounted to a steel pier. The steel pier is bolted to a 14 ton concrete substructure that is about 5 feet in the ground under the floor. The concrete section has lots of rebar and iron meshing inside of it. Lightning has taken out his computer control in the base three times in less than a year. The last two times, nothing was plugged into the unit so the base was simply at ground potential. It appears that because of the bedrock characteristics of this mountain, he is getting hit from the ground itself. I can't think of any other way. Someone emailed him the message below this morning as a possible solution, however I would be more inclined to install a tower or something a bit further to serve as a lightning rod. Maybe even treat the ground around the tower with Copper Sulfate to something similar to help give it a good ground. The suggestion below about running a copper perimeter 10' around his observatory seems like it might add to the problem. 10 feet does not sound like enough distance to be absorbing a direct hit of lightning. Since the base of the scope and the pier are both metal, there is really no way to isolate the telescope computer away from this. It is much too heavy to use nylon bolts and an insulating pad between the pier and concrete. Any ideas or suggestions? Thanks & 73, Brian / w5ami - Original Message - From: "P. Clay Sherrod" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> > No way at allin fact I am convinced now that the lightening is coming up through the > ground. > I talked to an electronics guy yesterday (he owns SoundCraft) that suggested I build a #3 > copper perimeter ground around the base of the observatory, about 10 feet away from the > walls with grounding rods on two opposing corners.he says the problem up here is that > you cannot get a proper ground on this mountain because of the rock. > ___ AMRadio mailing list AMRadio@mailman.qth.net http://mailman.qth.net/mailman/listinfo/amradio Kim Elmore, Ph.D. University of Oklahoma Cooperative Institute for Mesoscale Meteorological Studies "All of weather is divided into three parts: Yes, No, and Maybe. The greatest of these is Maybe" The original Latin appears to be garbled.
[AMRadio] Somewhat Off topic - lightning protection
This is somewhat off-topic, however the issue of lightning protection is important, and knowing how knowledgeable our members are, I thought someone might have a solution to the following problem.. My brother has a very expensive telescope in an observatory located on Petit Jean Mtn. in Arkansas. His telescope has a computerized tracking and "GoTo" system built into the base of the mount which is mounted to a steel pier. The steel pier is bolted to a 14 ton concrete substructure that is about 5 feet in the ground under the floor. The concrete section has lots of rebar and iron meshing inside of it. Lightning has taken out his computer control in the base three times in less than a year. The last two times, nothing was plugged into the unit so the base was simply at ground potential. It appears that because of the bedrock characteristics of this mountain, he is getting hit from the ground itself. I can't think of any other way. Someone emailed him the message below this morning as a possible solution, however I would be more inclined to install a tower or something a bit further to serve as a lightning rod. Maybe even treat the ground around the tower with Copper Sulfate to something similar to help give it a good ground. The suggestion below about running a copper perimeter 10' around his observatory seems like it might add to the problem. 10 feet does not sound like enough distance to be absorbing a direct hit of lightning. Since the base of the scope and the pier are both metal, there is really no way to isolate the telescope computer away from this. It is much too heavy to use nylon bolts and an insulating pad between the pier and concrete. Any ideas or suggestions? Thanks & 73, Brian / w5ami - Original Message - From: "P. Clay Sherrod" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> > No way at allin fact I am convinced now that the lightening is coming up > through the > ground. > I talked to an electronics guy yesterday (he owns SoundCraft) that suggested > I build a #3 > copper perimeter ground around the base of the observatory, about 10 feet > away from the > walls with grounding rods on two opposing corners.he says the problem up > here is that > you cannot get a proper ground on this mountain because of the rock. >
