|
Base Antenna Mounting
Planning to install a base antenna as soon as things warm up and could use some
help.......... So far I have an Imax 99 antenna. I was thinking of attaching it to the garage side of my house which is about~20 feet high at the peak. I would take a 5' piece of antenna mast and pound it several feet into the ground to secure the bottom and then attach 2 more 10' pieces on top of that. The mast could be secured to the house with several of those wall mount brackets. How does this sound so far? Now I understand that it must be grounded. Would having the bottom section of mast pounded into the ground as I mentioned suffice? or will I need to attach it to a seperate 8' ground rod? If a seperate rod is needed, do I attach the ground wire to the antenna mounting plate or the mast or either? Near the top of the mast or near the bottom? I also have read of the need for a 'static discharge unit' for my coax. Could anyone recommend one? Google searches are not helping me out much. Have some more questions, but this seems enough for now. Any help would be really appreciated. I've been trying to piece information together from the web, but still need some more help. Thanks! |
|
Richard Cranium wrote: (Zeeeeeeee3) wrote in message ... Planning to install a base antenna as soon as things warm up and could use some help.......... So far I have an Imax 99 antenna. I was thinking of attaching it to the garage side of my house which is about~20 feet high at the peak. I would take a 5' piece of antenna mast and pound it several feet into the ground to secure the bottom and then attach 2 more 10' pieces on top of that. The mast could be secured to the house with several of those wall mount brackets. How does this sound so far? It sounds like it'll wobble, but it should hold the antenna. For best performance, however you'll need to get the base of the antenna a minimum of one wavelength (about 36 feet) off the ground, and I don't recommend you use 10 foot mast sections for that. Now I understand that it must be grounded. Would having the bottom section of mast pounded into the ground as I mentioned suffice? or will I need to attach it to a seperate 8' ground rod? If a seperate rod is needed, do I attach the ground wire to the antenna mounting plate or the mast or either? Near the top of the mast or near the bottom? I'd use an 8 foot Ground rod installed close to the bottom of the mast, then connect them with the largest wire (or braid) you can find. Assuming decent connections between the mast sections you should make the connection at the bottom of the mast. In most locations (unless you live in a swamp) you need to go down five feet before you make a good Ground connection anyhow. I also have read of the need for a 'static discharge unit' for my coax. Could anyone recommend one? Google searches are not helping me out much. Check out Universal Radio on the web. They have those units. Have some more questions, but this seems enough for now. Any help would be really appreciated. I've been trying to piece information together from the web, but still need some more help. Thanks! if you intend to use a ground rod try and keep it at least 4' away from the foundation of the house as many times contractors will back fill around it with all sorts of stuff when the house is going up. i dug a 3 foot pit and put 4 rods at 90d intervals (for stability) with a 5' pole in the middle as a base and filled it with cement. |
Zeeeeeeee3 wrote:
Planning to install a base antenna as soon as things warm up and could use some help.......... So far I have an Imax 99 antenna. I was thinking of attaching it to the garage side of my house which is about~20 feet high at the peak. I would take a 5' piece of antenna mast and pound it several feet into the ground to secure the bottom and then attach 2 more 10' pieces on top of that. The mast could be secured to the house with several of those wall mount brackets. How does this sound so far? Now I understand that it must be grounded. Would having the bottom section of mast pounded into the ground as I mentioned suffice? or will I need to attach it to a seperate 8' ground rod? If a seperate rod is needed, do I attach the ground wire to the antenna mounting plate or the mast or either? Near the top of the mast or near the bottom? I also have read of the need for a 'static discharge unit' for my coax. Could anyone recommend one? Google searches are not helping me out much. Have some more questions, but this seems enough for now. Any help would be really appreciated. I've been trying to piece information together from the web, but still need some more help. Thanks! I do not worry about a static discharge if the antenna is grounded. Hell, if lightning its your house all you are going to worry about is your radio? I am thinking this is a good time to have the insurance paid up... -- Mike reply: m3425man at bevcomm.net Powered by Mandrake Linux since 5 February, 2003 Idiots (monkeys) can be trained, though morons are out of luck... Then there are those leaders who make policies and decisions based on whatever they dream up. They reject recommendations from the people on the ground or those who have excellent knowledge of the operations. I call them "combat confusers." |
I do not worry about a static discharge if the antenna is grounded. Hell, if
lightning its your house all you are going to worry about is your radio? I am thinking this is a good time to have the insurance paid up... Is the static discharge unit only to protect the radio? I was under the impression that it would also help prevent lightning strikes. Thanks |
|
In ,
(Twistedhed) wrote: From: (Zeeeeeeee3) I do not worry about a static discharge if the antenna is grounded. Hell, if lightning its your house all you are going to worry about is your radio? I am thinking this is a good time to have the insurance paid up... _ Is the static discharge unit only to protect the radio? I was under the impression that it would also help prevent lightning strikes. Thanks All bets are off with a lightning strike. No device can offer 100% protection against a direct strike. Unplugging the coax from the radio when not in use comes pretty darn close. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
From: (Frank=A0Gilliland)
In , (Twistedhed) wrote: From: (Zeeeeeeee3) I do not worry about a static discharge if the antenna is grounded. Hell, if lightning its your house all you are going to worry about is your radio? I am thinking this is a good time to have the insurance paid up... _ (Is the static discharge unit only to protect the radio? I was under the impression that it would also help prevent lightning strikes. Thanks) All bets are off with a lightning strike. No device can offer 100% protection against a direct strike. Unplugging the coax from the radio when not in use comes pretty darn close. No "device" can offer 100% protection against a direct lightning strike. -----=3D Posted via Newsfeeds.Com, Uncensored |
On Thu, 12 Feb 2004 13:12:19 -0800, Frank Gilliland
wrote: In , (Twistedhed) wrote: From: (Zeeeeeeee3) I do not worry about a static discharge if the antenna is grounded. Hell, if lightning its your house all you are going to worry about is your radio? I am thinking this is a good time to have the insurance paid up... _ Is the static discharge unit only to protect the radio? I was under the impression that it would also help prevent lightning strikes. Thanks All bets are off with a lightning strike. No device can offer 100% protection against a direct strike. Unplugging the coax from the radio when not in use comes pretty darn close. Maybe to protect the radio, If your antenna is hit, and your coax is disconnected from your radio , the potential across the connector can be hundreds of thousands of volts. The resulting arc can set fire to adjacent materials. |
|
In ,
(Twistedhed) wrote: From: (Frank*Gilliland) In , (Twistedhed) wrote: From: (Zeeeeeeee3) I do not worry about a static discharge if the antenna is grounded. Hell, if lightning its your house all you are going to worry about is your radio? I am thinking this is a good time to have the insurance paid up... _ (Is the static discharge unit only to protect the radio? I was under the impression that it would also help prevent lightning strikes. Thanks) All bets are off with a lightning strike. No device can offer 100% protection against a direct strike. Unplugging the coax from the radio when not in use comes pretty darn close. No "device" can offer 100% protection against a direct lightning strike. My goodness but you are predictable. First off, you have limited comprehension of your limited vocabulary. From Webster's: device -- n. 1. a thing devised; plan. 2. a scheme; trick. 3. a mechanical contrivance; invention...... Second, disconnecting the coax from the radio is often done with a "device", or haven't you heard of this new gizmo on the market called the 'switch'? Third, your communication deficit is acting up again. Read the original post: "....I was under the impression that it would also help prevent lightning strikes." Unless you are from a different planet with some kind of wonderful new technology that can actually change the weather at will, no "device" can prevent lightning strikes, period. Now go fly a kite, Dave. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
No, it is what it says, for static discharge. It won't prevent
strikes. Disconnect all cables before they enter your house and ground them. Ok thanks. Follow-up question then.......why do I want to get rid of the static? What if I don't? Thanks |
"Twistedhed" wrote in message ... From: (Frank Gilliland) In , (Twistedhed) wrote: From: (Zeeeeeeee3) I do not worry about a static discharge if the antenna is grounded. Hell, if lightning its your house all you are going to worry about is your radio? I am thinking this is a good time to have the insurance paid up... _ (Is the static discharge unit only to protect the radio? I was under the impression that it would also help prevent lightning strikes. Thanks) All bets are off with a lightning strike. No device can offer 100% protection against a direct strike. Unplugging the coax from the radio when not in use comes pretty darn close. No "device" can offer 100% protection against a direct lightning strike. Your both right, but you all forgot to tell him to unplug the radio from the wall too. Landshark -- Treat people as if they were what they ought to be and you will help them become what they are capable of becoming. |
|
On Fri, 13 Feb 2004 14:11:40 GMT, "Landshark"
wrote: "Twistedhed" wrote in message ... From: (Frank Gilliland) In , (Twistedhed) wrote: From: (Zeeeeeeee3) I do not worry about a static discharge if the antenna is grounded. Hell, if lightning its your house all you are going to worry about is your radio? I am thinking this is a good time to have the insurance paid up... _ (Is the static discharge unit only to protect the radio? I was under the impression that it would also help prevent lightning strikes. Thanks) All bets are off with a lightning strike. No device can offer 100% protection against a direct strike. Unplugging the coax from the radio when not in use comes pretty darn close. No "device" can offer 100% protection against a direct lightning strike. Your both right, but you all forgot to tell him to unplug the radio from the wall too. Landshark Not just his radio. My tower got hit last year, no damage to my radios, they were disconnected and unplugged. I'm guessing due to an induced charge in the wiring in my house, I lost 2 TV sets, 1 computer, my router and wireless access point. I now unplug just about everything when storms are on the way. |
LOL,,only your off-topic sidestep definitions don't apply in this case.
The original poster was referring to a device, as in "gadget", not a "scheme",such as you presented in your desperate squirm for deflection. In fact, all had no problem comprehending such, with the sole exception of your self,,,...tsk tsk.,,and here you go again, the low self-esteem and self-hatred you are forced to deal with, ****ing you off to no end, manifesting in misdirected anger from your darkness. Such hostility for no reason other than your personal problems.....that makes you a .......lid. |
In ,
(Twistedhed) wrote: LOL,,only your off-topic sidestep definitions don't apply in this case. The original poster was referring to a device, as in "gadget", not a "scheme",such as you presented in your desperate squirm for deflection. In fact, all had no problem comprehending such, with the sole exception of your self,,,...tsk tsk.,,and here you go again, the low self-esteem and self-hatred you are forced to deal with, ****ing you off to no end, manifesting in misdirected anger from your darkness. Such hostility for no reason other than your personal problems.....that makes you a ......lid. SOBR. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
The antenna requires an earth ground, first, as required by
National Electrical Code. That mounting rod should be connected to an eight+ foot earth ground rod (available even in Home Depot and Lowes). This required by NEC for human safety, but also to protect transistors. Incoming wire should enter building at the service entrance so that a ground block (maybe $1 at Radio Shack or Home Depot) connects 'less than 10 feet' to the building's single point earth ground. Same earthing ground that also connects to AC electric, telephone, and cable TV wire. Do not even think an AC receptacle or water faucet will provide that necessary earthing. NEC requirements have changed since 1990 to require a service entrance ground rod. You may need to install this earth ground rod at the service entrance. Many homes don't even have that much which is another reason why some homes suffer household electronics damage. Principles are demonstrated in this figure. Note an antenna tower and building each have their own earth ground. Each is earthed as if it were a separate structure. Every incoming wire makes a connection to that earth ground. To make the 'system' work better, a ground wire interconnects the antenna and building earth grounds: http://services.erico.com/public/lib...es/tncr002.pdf Static is irrelevant. A few hundred volts of static will not damage any properly built radio. You could even static shock your car radio antenna or a portable radio antenna without damage. That would be as much as 18,000 volts - and still no damage. The earthing is required by NEC for human safety AND also provides transistor safety. If lightning is provided a path to earth ground via that exterior rod, then it too will not seek earth ground, destructively, via your radio. Direct strike lightning damage is that easily avoided. Unfortunately, too many don't have necessary earthing, suffer damage, and then declare nothing could have helped. Generations of technical history say otherwise. Its all about earthing - as even required by code. Zeeeeeeee3 wrote: Ok thanks. Follow-up question then.......why do I want to get rid of the static? What if I don't? Thanks |
On Fri, 13 Feb 2004 14:41:50 -0500, w_tom wrote:
The antenna requires an earth ground, first, as required by National Electrical Code. That mounting rod should be connected to an eight+ foot earth ground rod (available even in Home Depot and Lowes). This required by NEC for human safety, but also to protect transistors. Where in the NEC code does it say that you need an earth ground to protect transistors? Incoming wire should enter building at the service entrance so that a ground block (maybe $1 at Radio Shack or Home Depot) connects 'less than 10 feet' to the building's single point earth ground. Same earthing ground that also connects to AC electric, telephone, and cable TV wire. Do not even think an AC receptacle or water faucet will provide that necessary earthing. NEC requirements have changed since 1990 to require a service entrance ground rod. You may need to install this earth ground rod at the service entrance. Many homes don't even have that much which is another reason why some homes suffer household electronics damage. Principles are demonstrated in this figure. Note an antenna tower and building each have their own earth ground. Each is earthed as if it were a separate structure. Every incoming wire makes a connection to that earth ground. To make the 'system' work better, a ground wire interconnects the antenna and building earth grounds: What figure? Do you work for erico? http://services.erico.com/public/lib...es/tncr002.pdf Whats this link? Have one that works? Static is irrelevant. A few hundred volts of static will not damage any properly built radio. You could even static shock your car radio antenna or a portable radio antenna without damage. That would be as much as 18,000 volts - and still no damage. Sorry, static is not irrelevant. You need to read up on static damage before you make such foolish posts. Every electronics manufacturer in the world takes great lengths to control static. When you talk about static shocking your car radio antenna, or portable radio antenna without damage, you need to look at other paths that the static electricity would be taking. Would you allow me to connect your CB antenna connection of your radio directly to an A.C. line? Thats only 115 volts. The earthing is required by NEC for human safety AND also provides transistor safety. If lightning is provided a path to earth ground via that exterior rod, then it too will not seek earth ground, destructively, via your radio. Direct strike lightning damage is that easily avoided. Unfortunately, too many don't have necessary earthing, suffer damage, and then declare nothing could have helped. Generations of technical history say otherwise. Its all about earthing - as even required by code. Last time I read, current seeks all and any paths to ground. Has that changed? Direct strike lightning damage isn't as easy as earth grounding your antenna. Hopefully no one else will believe your B.S. that all you need to do is earth ground your antenna and electrical entrance box unless you are willing to pay for any damage that they receive following your instructions. Zeeeeeeee3 wrote: Ok thanks. Follow-up question then.......why do I want to get rid of the static? What if I don't? Thanks |
Put it in an empty jim beam bottle
In article , Twistedhed says... LOL,,only your off-topic sidestep definitions don't apply in this case. The original poster was referring to a device, as in "gadget", not a "scheme",such as you presented in your desperate squirm for deflection. In fact, all had no problem comprehending such, with the sole exception of your self,,,...tsk tsk.,,and here you go again, the low self-esteem and self-hatred you are forced to deal with, ****ing you off to no end, manifesting in misdirected anger from your darkness. Such hostility for no reason other than your personal problems.....that makes you a ......lid. |
On 13 Feb 2004 12:44:50 -0800, Harmony wrote:
Put it in an empty jim beam bottle LOL, I like that... old wives tale was a mason jar... |
In , w_tom wrote:
......Same earthing ground that also connects to AC electric, telephone, and cable TV wire..... snip ......... Note an antenna tower and building each have their own earth ground. Each is earthed as if it were a separate structure. Every incoming wire makes a connection to that earth ground. To make the 'system' work better, a ground wire interconnects the antenna and building earth grounds: ........BAD idea. Tying your ground rods together makes a ground loop, which is deadly for radio equipment. Use a completely -seperate- ground system for your radio. Sink a ground rod where the coax enters the shack, tie the coax shield directly to this rod (don't forget to waterproof the connection), and run your ground strap and coax as close together as possible. Here's a diagram: http://www.aimcomm.net/sparky/ground.gif DON'T rely on your coax shield for a ground strap!!! You can braid a heavy-duty strap using old power cords and it shouldn't cost you more than a few dollars at the local thrift shop. If AC noise becomes a problem, rewire the AC outlets used by the radio so their ground goes to the new ground rod via the ground strap. Do NOT connect the neutral (white) wire to this ground! http://services.erico.com/public/lib...es/tncr002.pdf Page has moved. Update your link. Static is irrelevant. A few hundred volts of static will not damage any properly built radio. You could even static shock your car radio antenna or a portable radio antenna without damage. That would be as much as 18,000 volts - and still no damage. Many radios aren't built "properly", and most modern radios use JFET or MOSFET frontends, which are VERY suseptible to damage from static, even from potentials as low as 50 volts (the breakdown potential of the protection diodes). That's not the only problem -- static buildup on the antenna causes horrific noise! Fortunately, the best solution is an easy one: shunt the center conductor of your coax to ground with an RF choke, something on the order of 1 milliHenry or larger (even an audio or power supply choke will work). Locate the choke at the grounding block (see diagram) as any lightning strike will travel through that choke and you don't want it inside the shack when that happens. On the upside, it makes a beautiful blob of copper and iron that you could probably sell on ebay for a decent price (after the smell goes away, of course). The earthing is required by NEC for human safety AND also provides transistor safety. If lightning is provided a path to earth ground via that exterior rod, then it too will not seek earth ground, destructively, via your radio. Direct strike lightning damage is that easily avoided. Wrong. If the coax is plugged into the radio when lightning hits the antenna, it's safe to assume that your radio will fry. Period. Doesn't matter how much protection you have. Why? Because lightning packs a few million volts (not an exaggeration) and will jump just about any gap to ground. But gaps are also resistors, and since lighting also carries a few million amps (again, not an exaggeration), you are going to have a SIGNIFICANT voltage potential on your coax. In fact, the potential and current are so high that the core insulation breaks down for the full length of the coax and it is literally cooked from end to end. I've seen it more than once. And that's WITH proper grounding! Unplug the coax from the radio when not in use. If you want to use a "device", get one of those big blade switches so there is a big gap, and wire it so the antenna is shorted to ground when not connected to the radio. Unfortunately, too many don't have necessary earthing, suffer damage, and then declare nothing could have helped. Generations of technical history say otherwise. Its all about earthing - as even required by code. Get some field experience. THEN come here and talk about lightning protection. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
|
Manufacturer changed URL for that Technical Note again:
TN CR 002 The Need for Coordinated Protection http://www.erico.com/public/library/...es/tncr002.pdf This figure demonstrates how a radio can be protected even from lightning strikes. Static is irrelevant to radios because, as was posted Every electronics manufacturer ... takes great lengths to control static. If static on an antenna was destructive to a radio, then every time a human static discharges to that radio (many times higher voltage), then the radio is damaged. But human static discharge does not damage those JFETs. Internal protection easily installed because static has such low current AND short duration. Radio design assumes an antenna has been properly earthed as even required by the NEC which therefore makes internal protection effective. Cell phone towers, 911 dispatcher radios, telephone switching computers connected to overhead wires everywhere in town. All must suffer direct strikes and not be damaged - as was standard even before WWII. Why? Earthing, as described in the below text, and demonstrated in that manufacturer's figure makes protection even inside the radio effective. If such earthing was not effective, then 911 emergency dispatch and telephone operators would have to remove headsets (stopped working) during every thunderstorm. They don't stop working, do they. Protection so routine that it even makes static electric discharge problems irrelevant and trivial by comparison. OPs antenna and antenna lead must connect as demonstrated by that industry professional's technical note. For that matter, visit this and many other 'real world' manufacturers whose products are also effective because they discuss the most critical component - earthing. Lancer wrote: On Fri, 13 Feb 2004 14:41:50 -0500, w_tom wrote: The antenna requires an earth ground, first, as required by National Electrical Code. That mounting rod should be connected to an eight+ foot earth ground rod (available even in Home Depot and Lowes). This required by NEC for human safety, but also to protect transistors. Incoming wire should enter building at the service entrance so that a ground block (maybe $1 at Radio Shack or Home Depot) connects 'less than 10 feet' to the building's single point earth ground. Same earthing ground that also connects to AC electric, telephone, and cable TV wire. Do not even think an AC receptacle or water faucet will provide that necessary earthing. NEC requirements have changed since 1990 to require a service entrance ground rod. You may need to install this earth ground rod at the service entrance. Many homes don't even have that much which is another reason why some homes suffer household electronics damage. Principles are demonstrated in this figure. Note an antenna tower and building each have their own earth ground. Each is earthed as if it were a separate structure. Every incoming wire makes a connection to that earth ground. To make the 'system' work better, a ground wire interconnects the antenna and building earth grounds: Static is irrelevant. A few hundred volts of static will not damage any properly built radio. You could even static shock your car radio antenna or a portable radio antenna without damage. That would be as much as 18,000 volts - and still no damage. The earthing is required by NEC for human safety AND also provides transistor safety. If lightning is provided a path to earth ground via that exterior rod, then it too will not seek earth ground, destructively, via your radio. Direct strike lightning damage is that easily avoided. Unfortunately, too many don't have necessary earthing, suffer damage, and then declare nothing could have helped. Generations of technical history say otherwise. Its all about earthing - as even required by code. |
Unfortunately Frank Gilliland has exaggerated his numbers
due to insufficient experience and too much time listening to myths. His numbers will be exposed as fiction. Field experience says repeatedly that antenna and radio can suffer direct strikes without damage. That is proven about 25 times every year atop Empire State Building since the 1930s. According to Frank, they must suffer damage 25 times per year. Let's start with his numbers. Millions of volts? Yes. But same voltage does not appear everywhere in a circuit - basic circuit theory. Those millions of voltage are in the sky. Surge protection is about making those millions of voltage appear elsewhere which is why industry professionals discuss impedance. A low impedance connection to earth means no millions of volts. Millions of amps? Only in dreams. Most lightning is below 20,000 amps and of such short duration as to not be high energy. Lightning typically so low energy at the strike location (not to be confused with what is miles above) that well over 90% of all trees struck leave no indication of that strike. How big need a wire be to shunt (earth) lightning? Even the US Army training manual TM5-690 requires 10 AWG wire to conduct the direct lightning strike without damage. Same wire found in 20 or 30 amp AC electric boxes because lightning is not the millions of amps so often claimed in urban myths. Unlike Frank, numbers are provided by multiple, reliable sources. Another who does this for a living: From Colin Baliss "Transmission & Distribution Electrical Engineering": Although lightning strikes have impressive voltage and current values (typically hundreds to thousands of kV and 10-100 kA) the energy content of the discharge is relatively low ... or Martin A Uman in All About Lightning Most of the energy available to the lightning is converted along the lightning channel to thunder, heat, light, and radio waves, leaving only a fraction available at the channel base for immediate use or storage. In short, Frank Gilliland's numbers are classic myths. Pre WWII ham radio operators demonstrated what was required for protection. First they would disconnect antenna and still suffer damage. Then placed antenna lead in a mason jar, and still suffered damage. But when antenna was connected to earth ground, then no damage. Neither a mason jar nor "one of those big blade switches" sufficiently blocks destructive transients. Of course not. Lightning was not blocked by miles of air. Is a mason jar or knife switch to do what miles of air could not? Of course not. For no damage, provide the destructive transient what it wants - earth ground. zeeeeeeee's antenna installation is demonstrated by a figure in TN CR 002 The Need for Coordinated Protection (corrected URL) http://www.erico.com/public/library/...es/tncr002.pdf Need anyone suffer damage from direct lightning? Of course not. Such damage is considered a human failure because proper earthing is so effective and so inexpensive. Another professional who makes that point in direct contradiction to posted myths: http://www.harvardrepeater.org/news/lightning.html Well I assert, from personal and broadcast experience spanning 30 years, that you can design a system that will handle *direct lightning strikes* on a routine basis. It takes some planning and careful layout, but it's not hard, nor is it overly expensive. At WXIA-TV, my other job, we take direct lightning strikes nearly every time there's a thunderstorm. Our downtime from such strikes is almost non-existant. The last time we went down from a strike, it was due to a strike on the power company's lines knocking *them* out, ... Since my disasterous strike, I've been campaigning vigorously to educate amateurs that you *can* avoid damage from direct strikes. The belief that there's no protection from direct strike damage is *myth*. ... The keys to effective lightning protection are surprisingly simple, and surprisingly less than obvious. Of course you *must* have a single point ground system that eliminates all ground loops. And you must present a low *impedance* path for the energy to go. That's most generally a low *inductance* path rather than just a low ohm DC path. Important point. This professional did not say 'resistance'. He said 'impedance' which is why wire length is so critical. 'Impedance' is why an incoming wire (antenna, CATV, telephone) must first drop down to make a short connection to earth before rising up to enter a building. Just one of the "careful layout" techniques learned from underlying theory tempered by decades of experience. zeeeeeeee's tower requires earthing to meet human safety requirements of National Electrical Code AND to provide transistor safety. Earthing required twice over. Once properly earthed, then even unplugging for protection would be unnecessary - as has been demonstrated too many times at too many locations since before WWII. Frank Gilliland wrote: In , w_tom wrote: The earthing is required by NEC for human safety AND also provides transistor safety. If lightning is provided a path to earth ground via that exterior rod, then it too will not seek earth ground, destructively, via your radio. Direct strike lightning damage is that easily avoided. Wrong. If the coax is plugged into the radio when lightning hits the antenna, it's safe to assume that your radio will fry. Period. Doesn't matter how much protection you have. Why? Because lightning packs a few million volts (not an exaggeration) and will jump just about any gap to ground. But gaps are also resistors, and since lighting also carries a few million amps (again, not an exaggeration), you are going to have a SIGNIFICANT voltage potential on your coax. In fact, the potential and current are so high that the core insulation breaks down for the full length of the coax and it is literally cooked from end to end. I've seen it more than once. And that's WITH proper grounding! Unplug the coax from the radio when not in use. If you want to use a "device", get one of those big blade switches so there is a big gap, and wire it so the antenna is shorted to ground when not connected to the radio. |
Actually that astrosurf.com author misses the point. He
cites a benchmark in surge protection, then assumes the surge protector (or more of them) provides protection. Even Polyphaser does not make that claim. Far better information are the legendary application notes from Polyphaser. Do they discuss their products? Of course not. Polyphaser discusses THE protection - earthing. Making a short connection to earth is so critical that Polyphaser even makes protectors with NO connection. Instead the protector mounts directly ON earth ground. Polyphaser application notes are at: http://www.polyphaser.com/ppc_pen_home.asp Why did the author suffer damage? Every damaged item was part of a circuit from cloud to earth. Only damaged were items that completed a path to earth. BTW, those manufacturers who discuss earthing make serious protectors. Visit their product line appreciate what serious protector products are. Randy wrote: http://www.astrosurf.com/lombry/qsl-...protection.htm This site has some good info. |
"w_tom" wrote in message ... Unfortunately Frank Gilliland has exaggerated his numbers due to insufficient experience and too much time listening to myths. His numbers will be exposed as fiction. Field experience says repeatedly that antenna and radio can suffer direct strikes without damage. That is proven about 25 times every year atop Empire State Building since the 1930s. According to Frank, they must suffer damage 25 times per year. Let's start with his numbers. Millions of volts? Yes. But same voltage does not appear everywhere in a circuit - basic circuit theory. Those millions of voltage are in the sky. Surge protection is about making those millions of voltage appear elsewhere which is why industry professionals discuss impedance. A low impedance connection to earth means no millions of volts. Millions of amps? Only in dreams. Most lightning is below 20,000 amps and of such short duration as to not be high energy. Lightning typically so low energy at the strike location (not to be confused with what is miles above) that well over 90% of all trees struck leave no indication of that strike. How big need a wire be to shunt (earth) lightning? Even the US Army training manual TM5-690 requires 10 AWG wire to conduct the direct lightning strike without damage. Same wire found in 20 or 30 amp AC electric boxes because lightning is not the millions of amps so often claimed in urban myths. Unlike Frank, numbers are provided by multiple, reliable sources. Another who does this for a living: From Colin Baliss "Transmission & Distribution Electrical Engineering": Although lightning strikes have impressive voltage and current values (typically hundreds to thousands of kV and 10-100 kA) the energy content of the discharge is relatively low ... or Martin A Uman in All About Lightning Most of the energy available to the lightning is converted along the lightning channel to thunder, heat, light, and radio waves, leaving only a fraction available at the channel base for immediate use or storage. In short, Frank Gilliland's numbers are classic myths. Pre WWII ham radio operators demonstrated what was required for protection. First they would disconnect antenna and still suffer damage. Then placed antenna lead in a mason jar, and still suffered damage. But when antenna was connected to earth ground, then no damage. Neither a mason jar nor "one of those big blade switches" sufficiently blocks destructive transients. Of course not. Lightning was not blocked by miles of air. Is a mason jar or knife switch to do what miles of air could not? Of course not. For no damage, provide the destructive transient what it wants - earth ground. zeeeeeeee's antenna installation is demonstrated by a figure in TN CR 002 The Need for Coordinated Protection (corrected URL) http://www.erico.com/public/library/...es/tncr002.pdf Need anyone suffer damage from direct lightning? Of course not. Such damage is considered a human failure because proper earthing is so effective and so inexpensive. So, you claim that ALL lightning strikes can be safely shunted to Earth, with no damage along the path? Well, I don't have 30 years experience in the electrical transmission and distribution industry, but I do have 25 years. And I have seen properly earth grounded transmission and distribution poles where the awg #6-#4 CU wires were mostly vaporized. Sure, there were bits and short pieces left, but for the most part, the wire was gone. I confer with you most of what you say, but you would be not completely honest to say that all lightning strikes can be earthed with no damage. Possible? Maybe. Practical? Nope.There will be strikes of magnitude where practical techniques fail. |
In , w_tom wrote:
Unfortunately Frank Gilliland has exaggerated his numbers due to insufficient experience and too much time listening to myths. His numbers will be exposed as fiction. Field experience says repeatedly that antenna and radio can suffer direct strikes without damage. That is proven about 25 times every year atop Empire State Building since the 1930s. According to Frank, they must suffer damage 25 times per year. CB radio antennas are not commercial station towers. The latter are verticals that have a direct connection to ground and the ground radials. Actually, an AM broadcast tower is almost a perfect lightning rod by design because it not only shunts the lightning directly to ground, but also distributes the power from the strike over the whole counterpoise field. So the tower stays at a relatively low potential even during a direct strike. And what -does- manage to sneak onto the line has to deal with some rather expensive protection devices. Antennas mounted seperately on towers (FM/TV BC, cell, commercial, etc) have the same problems as any other antenna, but those problems are usually minimized by the use of coax. More below. Let's start with his numbers. Millions of volts? Yes. But same voltage does not appear everywhere in a circuit - basic circuit theory. Those millions of voltage are in the sky. Surge protection is about making those millions of voltage appear elsewhere which is why industry professionals discuss impedance. A low impedance connection to earth means no millions of volts. A low impedance ground is fine for AC line protection, but it doesn't guarantee lightning protection. We have all heard that lightning takes the shortest path to ground, but that's not really true since electricity will take EVERY path to ground available. Lightning creates it's own conduit from the clouds, but once it hits a conductor on the ground it behaves just like any other form of electricity -- almost. The fact is that wire has resistance, and the resistance of copper increases with temperature, which is what happens when it passes the current from a lightning strike. When that happens it will continue it's path to ground (assuming the wire doesn't fuse), but other paths will share more of the load. And because there is a resistance, there will also be a voltage potential across that resistance. If that voltage potential is high enough it will happily arc over to another ground path, and frequently does. More below. Millions of amps? Only in dreams. Most lightning is below 20,000 amps and of such short duration as to not be high energy. Lightning typically so low energy at the strike location (not to be confused with what is miles above) that well over 90% of all trees struck leave no indication of that strike. Let's take your figure of 20,000.... no, let's go even lower. Let's say only 1000 amps @ 1,000,000 volts. And let's say this is an unusual strike in that it only hits once, not multiple times like a normal strike. And let's say the duration of the hit is 1/10 of a second. This will be a pathetic bolt of lightning to be sure! Ok, so let's do some numbers: 1,000,000 Volts x 1000 Amps = 1,000,000,000 Watts 1,000,000,000 Watts x 0.1 sec = 1,000,000 Watt/sec One million joules is "low energy"? Get a grip. Trees struck by lightning usually -do- leave an indication of being struck, but most people don't climb them to search for the point of contact, which is typically nothing more than a spot about one or two cm in diameter that has been charred. And while the reason trees are able to survive direct lightning strikes is still the subject of debate, the reason they make good lightning rods (efficiently conducting the strike to ground) shouldn't be so suprising when you take a look at a cross-section of the root structure -- interesting how it resembles an electrical discharge, isn't it? Ok, back to your low impedance ground. A ground rod is used to make an electrical connection to the earth. But the impedance of that connection can be anywhere from a few ohms to a few hundred ohms, depending on the type of rod and the conditions of the soil. Let's just say we have a ground with an unbelievable impedance of 1 ohm (a solid-silver rod in a heavily mineralized salt-water marsh that was recently used for dumping copper turnings from a very poorly run machine shop)..... 1000 amps x 1 ohm = 1000 volts So with an almost impossibly good ground and a puny bolt of lightning you -still- have 1000 volts at the top of your ground rod. So a more typical ground impedance of 50 ohms (not coincidence) and a more typical lightning strike of 10,000 amps will put 500,000 volts on your grounding strap.....YIKES!!!!! This is a fact, and it certainly doesn't seem to jibe with your statement that the voltage at the bottom is insignificant! How big need a wire be to shunt (earth) lightning? Even the US Army training manual TM5-690 requires 10 AWG wire to conduct the direct lightning strike without damage. Ever hear the term "military intelligence"? Same wire found in 20 or 30 amp AC electric boxes because lightning is not the millions of amps so often claimed in urban myths. Unlike Frank, numbers are provided by multiple, reliable sources. The ground wire in house wiring is intended for fault protection, not lightning strikes. For example, if the hot wire in your vintage all-metal Craftsman drill suddenly comes loose and shorts to the case, since the case is grounded it will shunt the majority of the current to ground through the ground wire, not through the person using the drill. And if your breakers and wiring are up to code (neutral grounded at the box), that current lasts only for a very short time, limiting any damage to the person and the drill. Therefore, the ground wire in your house doesn't need to be as thick as the main wires, and it isn't. Next time you visit your local hardware store, look at the specs on a spool of house wire -- hot and neutral may be #10 while ground will be #12. Another spool may have a pair of #12 wires and #14 for ground. If this ground wire was intended for lightning protection, wouldn't it all be the same size? Fact: the NEC doesn't define ground wire size based on it's ability (or inability) to protect against lightning. Another who does this for a living: From Colin Baliss "Transmission & Distribution Electrical Engineering": Although lightning strikes have impressive voltage and current values (typically hundreds to thousands of kV and 10-100 kA) the energy content of the discharge is relatively low ... Relative to what? or Martin A Uman in All About Lightning Most of the energy available to the lightning is converted along the lightning channel to thunder, heat, light, and radio waves, leaving only a fraction available at the channel base for immediate use or storage. Then I guess all the people that have been killed by lightning didn't die from the power in the lightning, did they? And all the damage to electrical equipment caused by lightning wasn't from the lightning at all, was it? And that pro golfer that was knocked flat on the links by a nearby strike must have been hit in the head with a ball at the exact same time, huh? No, no and no..... The power of a bolt of lightning isn't the big issue here since it doesn't take much power to cause damage. The issue is how well you are protected from whatever amount of power that -does- make it to the surface. In short, Frank Gilliland's numbers are classic myths. Pre WWII ham radio operators demonstrated what was required for protection. First they would disconnect antenna and still suffer damage. Then placed antenna lead in a mason jar, and still suffered damage. But when antenna was connected to earth ground, then no damage. Neither a mason jar nor "one of those big blade switches" sufficiently blocks destructive transients. Of course not. Lightning was not blocked by miles of air. Is a mason jar or knife switch to do what miles of air could not? You bet it will! Suppose you use one of those basic air-gap devices. Ok, you have 10,000 amps passing through a gap that now consists of plasma. But even plasma has resistance and will develop a considerable voltage across it. Plus, there is the brief voltage potential that exists across the gap immediately before the plasma is ignited, as well as after it is extinguished. These are the voltages that will be developed across the conductors of the transmission line going into the shack. How high is that voltage? It can peak at several thousand volts, and the arc itself can develop several hundred volts across the points. That's enough to fry a radio. Even if the impedance is high coming into the shack, it will still destroy any overload protection in the radio, making it vulnerable to more serious damage from nothing more than a surge or static discharge. The coax doesn't offer much protection by itself, but it can limit the maximum voltage entering the shack (or coming down the tower from the antenna). Every type of coax has a core insulation that is rated for a certain breakdown, or 'pucture' voltage. RG-58 is rated for 1900 volts RMS, or roughly 2800 volts peak. That means the coax is going to permit 2800 volts into the shack before it fails and starts arcing internally. That's still enough to fry a radio. And that's assuming the lightning hits the antenna and not the coax. If it hits the coax, that's a different game altogether. There are other factors that can put large voltages on the coax, since inductive and capacitive reactances of a ground system, while small, can become very significant when the current is on the order of 10,000 amps. We can take that route too if you want. The fact is that simply sinking a ground rod is NOT ENOUGH. A large blade switch will easily block any voltage that can make it through the coax. Additionally, it will also protect the coax by shorting it, thereby preventing a voltage high enough to cause the insulation to fail. This is a method that has been proven time and time again since the beginning of radio. Of course not. For no damage, provide the destructive transient what it wants - earth ground. zeeeeeeee's antenna installation is demonstrated by a figure in TN CR 002 The Need for Coordinated Protection (corrected URL) http://www.erico.com/public/library/...es/tncr002.pdf "Equipotential Earth Bonding" = ground loop = bad news when using unbalanced transmission line (coax). Whoever made that design has no experience with radio communication systems, which is especially evident because most commercial stations bury their coax, affording a level of protection far superior to the design in your reference (....gawd I hate pdf's!). Need anyone suffer damage from direct lightning? Of course not. Such damage is considered a human failure because proper earthing is so effective and so inexpensive. Another professional who makes that point in direct contradiction to posted myths: http://www.harvardrepeater.org/news/lightning.html Well I assert, from personal and broadcast experience spanning 30 years, that you can design a system that will handle *direct lightning strikes* on a routine basis. It takes some planning and careful layout, but it's not hard, nor is it overly expensive. At WXIA-TV, my other job, we take direct lightning strikes nearly every time there's a thunderstorm. Our downtime from such strikes is almost non-existant. The last time we went down from a strike, it was due to a strike on the power company's lines knocking *them* out, ... Since my disasterous strike, I've been campaigning vigorously to educate amateurs that you *can* avoid damage from direct strikes. The belief that there's no protection from direct strike damage is *myth*. ... The keys to effective lightning protection are surprisingly simple, and surprisingly less than obvious. Of course you *must* have a single point ground system that eliminates all ground loops. And you must present a low *impedance* path for the energy to go. That's most generally a low *inductance* path rather than just a low ohm DC path. Important point. This professional did not say 'resistance'. He said 'impedance' which is why wire length is so critical. 'Impedance' is why an incoming wire (antenna, CATV, telephone) must first drop down to make a short connection to earth before rising up to enter a building. Just one of the "careful layout" techniques learned from underlying theory tempered by decades of experience. Although your statement is inconsistent with your pdf reference, the reason coax is sometimes physically located at ground level at the entrance to the shack is because of the differences between RF ground and DC ground, -not- because of the effect of inductive and/or capacitive reactance in a lightning strike. If that were the case then the antenna system would need to be 'tuned' for lightning, which is nearly impossible since lightning has no fixed frequency. zeeeeeeee's tower requires earthing to meet human safety requirements of National Electrical Code AND to provide transistor safety. Earthing required twice over. Once properly earthed, then even unplugging for protection would be unnecessary - as has been demonstrated too many times at too many locations since before WWII. It's obvious that you have no experience in the real world with lightning damage. Get some. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
Lightning builds plasma wires that can short high energy,
utility power through other copper wires. Lightning simply creates the short circuit. Then a higher source of energy - AC electric utility - follows to vaporize those copper wires. That point was described by Colin Baliss: Although lightning strikes have impressive voltage and current values (typically hundreds to thousands of kV and 10-100 kA) the energy content of the discharge is relatively low and most of the damage to power plant is caused by 'power follow-through current'. The lightning simply provides a suitable ionized discharge path. Yes direct strikes have caused damage. This was a problem in the early days of ESS-1 - the first electronic switching computers for telephone systems. And so engineers then reevaluated the earthing system in those few 'problem' Central Office buildings to correct the reason for electronic damage - human failure. Described above is not a best solution. But then a best solution is typically not required. Above described system will not avoid damage from every possible direct strike. But then many of these 'rare' direct strikes have never been experienced by many - maybe most - people. For example, something called hot lightning may discharge the entire cloud in one single strike. It has been observed - just like tornados have been observed (most people also will never witness a tornado in their lifetime). Defined here is effective protection for most direct lightning strikes. It costs so little. To enhance same for the other maybe 1%, serious facilities such as 911 systems, cell phone towers, telephone switch stations, and nuclear hardened maritime facilities spend far more than a few $10. They spend $thousands more on earthing alone just to also protect from the last 1% of worst case lightning strikes. I cite nuclear hardened facility especially since a 1998 IEEE paper described a Norwegian maritime station damaged by a lightning strike. They discovered major installation faults in the earthing system for what was suppose to be a nuclear EMP protected station. Faults that even permitted lightning to cause damage. Again, failure directly traceable to a human. Major construction required to repair a simple earthing flaw. Homes contain superior earthing systems that we still don't use today. Ufer grounds could have been installed using existing structure - if planned for when footing were poured. But we still don't install superior earthing systems in new homes 30 years after the transistor existed. Costs to use that Ufer ground on existing homes are now extreme because Ufer grounding was not enabled when house construction started. OP must make do with simple earth ground rods. Properly installed, the Original Poster is quite unlikely to suffer any damage from direct lightning strikes. For but a few $10, he gets a massive increase in direct lightning strike protection. Not perfect. Just a massive improvement. Randy wrote: So, you claim that ALL lightning strikes can be safely shunted to Earth, with no damage along the path? Well, I don't have 30 years experience in the electrical transmission and distribution industry, but I do have 25 years. And I have seen properly earth grounded transmission and distribution poles where the awg #6-#4 CU wires were mostly vaporized. Sure, there were bits and short pieces left, but for the most part, the wire was gone. I confer with you most of what you say, but you would be not completely honest to say that all lightning strikes can be earthed with no damage. Possible? Maybe. Practical? Nope.There will be strikes of magnitude where practical techniques fail. |
Cited was an industry professional who demonstrate simple
protection even for amateur radio installations. He discussed protection without damage for *all* radios, including repeaters. You think effective earthing requires what commercial broadcasters install? Yes, some so deny the power of earthing. Very little protects radios from most direct lightning strikes. However some will cry that such earthing cannot protect from the rare 1%. If earthing is only 99% effective, then no money should be spent - all earthing is useless? Reality, effective protection from direct lightning strikes is about simple and inexpensive earthing. Frank Gilliland has even posted unrealistic and fictional numbers, and then denies the power of earthing - a concept well proven in virtually every town throughout the world. BTW Frank, to correct your post: low *resistance* (not impedance) ground is fine for AC line protection. A low *impedance* ground is necessary for lightning protection. One must know the difference to understand simple earthing concepts - and why earthing is so effective. How can you be so critical of earthing and not even know the most basic of basics - impedance verse resistance? Even basic numbers such as the typical pulse width are silly speculation. Typical lightning strike is a classic 8/20 usec. That is microseconds - not 0.1 seconds - which is why lightning does not have the energy content of myth. Furthermore, 1,000,000 volts does not appear at that lightning strike. In fact a major destructive direct strike to the building is well defined in research papers - as to not exceed 6,000 volts. One should first learn the science. Basic electrical circuit theory makes it obvious why the millions of volts up there don't appear down here. Either those millions of volts must be up there or down here - cannot exist in both locations. Again, first semester circuit theory that every graduate of West Point and Annapolis has learned. Please first learn that basic circuit theory before disputing IEEE papers, other well proven research, and NEC requirements. Correctly noted is that most people don't climb trees to search for lightning damage to trees. But then researchers such as Alan Taylor of the US Forestry Service are not just most people. Lightning has such low energy that most every tree directly struck has no appreciative damage. Speculate all you want. He did the work and wrote the paper. Using your reasoning for why earth cannot conduct the electricity even in a badly polluted salt marsh: then obviously lightning could never conduct miles across the sky and obviously lightning does not strike a non conductive earth. Why does air conduct miles of lightning that only contains millions of volts? First learn the many stages of how air and earth become such excellent conductors. Does a cloud strike 5 miles diagonal to connect cloud to charges on earth? Of course not. Lightning travels 3 miles straight down and then 4 miles through earth to complete a circuit. Lightning takes a more conductive path via air and earth rather than an electrically longer 5 mile path only through air. Conductive earth is also why earthing a direct strike (the single point earth ground) is such effective protection from a direct strike. Because even simple concepts of impedance verses resistance are not understood, then even safety grounds (third prong in wall receptacle) are confused with earth ground. Safety ground is different from motherboard ground is different from chassis ground is different from automobile ground is different from breaker box ground is different from power plant ground is different from earth ground. Most all are interconnected, but are still electrically different. Learn about impedance. No earth ground is found in wall receptacles because the wire length - and therefore impedance - of that third prong wire is just too far from earth ground. Again, one must first understand impedance to appreciate what world renown experts (some quoted here) have said about earthing. It takes but a few milliamps to kill a human. Does that prove lightning must be a high energy event - because it too kills? Learn how easy a human can be killed before posting such assumptions. Even posted is that a buried coax is protected from lightning transients. That is ridiculous as even made bluntly obvious in a Polyphaser application note about damage to an improperly earthed telephone exchange; transient damage via buried wires. Obvious in that long reply - even basic electrical concepts are not understood. Real world professionals and generations of scientific experience prove basic earthing is effective protection. Even the NEC requires OP to earth ground his antenna also for human safety. Basic electrical knowledge - impedance verses resistance - was not even understood and still Frank said everyone is wrong about earthing. Frank Gilliland wrote: CB radio antennas are not commercial station towers. The latter are verticals that have a direct connection to ground and the ground radials. Actually, an AM broadcast tower is almost a perfect lightning rod by design because it not only shunts the lightning directly to ground, but also distributes the power from the strike over the whole counterpoise field. So the tower stays at a relatively low potential even during a direct strike. And what -does- manage to sneak onto the line has to deal with some rather expensive protection devices. Antennas mounted seperately on towers (FM/TV BC, cell, commercial, etc) have the same problems as any other antenna, but those problems are usually minimized by the use of coax. More below. Let's start with his numbers. Millions of volts? Yes. But same voltage does not appear everywhere in a circuit - basic circuit theory. Those millions of voltage are in the sky. Surge protection is about making those millions of voltage appear elsewhere which is why industry professionals discuss impedance. A low impedance connection to earth means no millions of volts. A low impedance ground is fine for AC line protection, but it doesn't guarantee lightning protection. We have all heard that lightning takes the shortest path to ground, but that's not really true since electricity will take EVERY path to ground available. Lightning creates it's own conduit from the clouds, but once it hits a conductor on the ground it behaves just like any other form of electricity -- almost. The fact is that wire has resistance, and the resistance of copper increases with temperature, which is what happens when it passes the current from a lightning strike. When that happens it will continue it's path to ground (assuming the wire doesn't fuse), but other paths will share more of the load. And because there is a resistance, there will also be a voltage potential across that resistance. If that voltage potential is high enough it will happily arc over to another ground path, and frequently does. More below. Millions of amps? Only in dreams. Most lightning is below 20,000 amps and of such short duration as to not be high energy. Lightning typically so low energy at the strike location (not to be confused with what is miles above) that well over 90% of all trees struck leave no indication of that strike. Let's take your figure of 20,000.... no, let's go even lower. Let's say only 1000 amps @ 1,000,000 volts. And let's say this is an unusual strike in that it only hits once, not multiple times like a normal strike. And let's say the duration of the hit is 1/10 of a second. This will be a pathetic bolt of lightning to be sure! Ok, so let's do some numbers: 1,000,000 Volts x 1000 Amps = 1,000,000,000 Watts 1,000,000,000 Watts x 0.1 sec = 1,000,000 Watt/sec One million joules is "low energy"? Get a grip. Trees struck by lightning usually -do- leave an indication of being struck, but most people don't climb them to search for the point of contact, which is typically nothing more than a spot about one or two cm in diameter that has been charred. And while the reason trees are able to survive direct lightning strikes is still the subject of debate, the reason they make good lightning rods (efficiently conducting the strike to ground) shouldn't be so suprising when you take a look at a cross-section of the root structure -- interesting how it resembles an electrical discharge, isn't it? Ok, back to your low impedance ground. A ground rod is used to make an electrical connection to the earth. But the impedance of that connection can be anywhere from a few ohms to a few hundred ohms, depending on the type of rod and the conditions of the soil. Let's just say we have a ground with an unbelievable impedance of 1 ohm (a solid-silver rod in a heavily mineralized salt-water marsh that was recently used for dumping copper turnings from a very poorly run machine shop)..... 1000 amps x 1 ohm = 1000 volts So with an almost impossibly good ground and a puny bolt of lightning you -still- have 1000 volts at the top of your ground rod. So a more typical ground impedance of 50 ohms (not coincidence) and a more typical lightning strike of 10,000 amps will put 500,000 volts on your grounding strap.....YIKES!!!!! This is a fact, and it certainly doesn't seem to jibe with your statement that the voltage at the bottom is insignificant! How big need a wire be to shunt (earth) lightning? Even the US Army training manual TM5-690 requires 10 AWG wire to conduct the direct lightning strike without damage. Ever hear the term "military intelligence"? Same wire found in 20 or 30 amp AC electric boxes because lightning is not the millions of amps so often claimed in urban myths. Unlike Frank, numbers are provided by multiple, reliable sources. The ground wire in house wiring is intended for fault protection, not lightning strikes. For example, if the hot wire in your vintage all-metal Craftsman drill suddenly comes loose and shorts to the case, since the case is grounded it will shunt the majority of the current to ground through the ground wire, not through the person using the drill. And if your breakers and wiring are up to code (neutral grounded at the box), that current lasts only for a very short time, limiting any damage to the person and the drill. Therefore, the ground wire in your house doesn't need to be as thick as the main wires, and it isn't. Next time you visit your local hardware store, look at the specs on a spool of house wire -- hot and neutral may be #10 while ground will be #12. Another spool may have a pair of #12 wires and #14 for ground. If this ground wire was intended for lightning protection, wouldn't it all be the same size? Fact: the NEC doesn't define ground wire size based on it's ability (or inability) to protect against lightning. Another who does this for a living: From Colin Baliss "Transmission & Distribution Electrical Engineering": Although lightning strikes have impressive voltage and current values (typically hundreds to thousands of kV and 10-100 kA) the energy content of the discharge is relatively low ... Relative to what? or Martin A Uman in All About Lightning Most of the energy available to the lightning is converted along the lightning channel to thunder, heat, light, and radio waves, leaving only a fraction available at the channel base for immediate use or storage. Then I guess all the people that have been killed by lightning didn't die from the power in the lightning, did they? And all the damage to electrical equipment caused by lightning wasn't from the lightning at all, was it? And that pro golfer that was knocked flat on the links by a nearby strike must have been hit in the head with a ball at the exact same time, huh? No, no and no..... .... It's obvious that you have no experience in the real world with lightning damage. Get some. |
In , w_tom wrote:
Cited was an industry professional who demonstrate simple protection even for amateur radio installations. He discussed protection without damage for *all* radios, including repeaters. You think effective earthing requires what commercial broadcasters install? Yes, some so deny the power of earthing. Very little protects radios from most direct lightning strikes. However some will cry that such earthing cannot protect from the rare 1%. If earthing is only 99% effective, then no money should be spent - all earthing is useless? Reality, effective protection from direct lightning strikes is about simple and inexpensive earthing. Frank Gilliland has even posted unrealistic and fictional numbers, and then denies the power of earthing - a concept well proven in virtually every town throughout the world. Now you are starting to twist my words. I never said proper grounding was ineffective. On the contrary, it's absolutely necessary. And while it -may- protect a radio against damage from most -nearby- strikes that would otherwise cause damage (probably the source of your 99% figure), grounding alone is -not- enough to protect against a -direct- strike to your average CB station, which is what we were talking about. The method I provided is enough to greatly increase the odds of the equipment surviving a -direct- strike. My information is based on over 25 years of real-life field experience as a CB operator, a military radio tech (USMC), a commercial radio tech, and a broadcast engineer. It is also based on a BS in Electronics Engineering (specialized degree), the basic laws of physics, detailed observations and common sense. It is -not- based on a few internet references that can be easily countered with a few other internet references. BTW Frank, to correct your post: low *resistance* (not impedance) ground is fine for AC line protection. A low *impedance* ground is necessary for lightning protection. One must know the difference to understand simple earthing concepts - and why earthing is so effective. How can you be so critical of earthing and not even know the most basic of basics - impedance verse resistance? Maybe you should read my posts again -- I have already addressed the issue of inductive and capacitive reactances. Or maybe you don't know that impedance equals resistance plus reactance. The fact is that lightning covers a wide spectrum of frequencies, so there is no way to 'tune' your ground for lightning, and therefore no way to establish a low impedance beyond keeping the resistance as low as possible. Even basic numbers such as the typical pulse width are silly speculation. Typical lightning strike is a classic 8/20 usec. That is microseconds - not 0.1 seconds - which is why lightning does not have the energy content of myth. Later..... Furthermore, 1,000,000 volts does not appear at that lightning strike. In fact a major destructive direct strike to the building is well defined in research papers - as to not exceed 6,000 volts. What research papers? Where can I read them? One should first learn the science. Basic electrical circuit theory makes it obvious why the millions of volts up there don't appear down here. Either those millions of volts must be up there or down here - cannot exist in both locations. Yes it can. First, you need to understand the basic fundamentals -- Ohm's law. A bolt of lightning will carry X amps along the full length of its path. So if that path experiences a point of high resistance, the result is high voltage. The point of high resistance might be an air-gap device or it might be a fused ground wire, both of which will put hundreds of thousands, or even millions, of volts on the line. But for the sake of argument, let's assume that the air-gap is sparking and the wire isn't melting. Ok, did you pay attention to the ground rod example? Apparently not. Let's try this again: 10,000 amps x 1 ohm = 10,000 volts Now I'm sure that you are going to whine about 'impedance', but the fact remains that no matter how much reactance the ground system may add, it still -adds- to the resistance, which is 1 ohm (for an exceptional ground, I might add). That means if there is -any- reactance, or a less than exceptional ground, the voltage will be HIGHER!!! And I suppose I have to show you the equation again for a -typical- household ground of 50 ohms: 10,000 amps x 50 ohms = 500,000 volts Now let's plug in your stroke duration numbers from above: 500,000 volts x 10,000 amps = 5,000,000,000 watts 5,000,000,000 watts x .000008 sec = 40,000 joules 40,000 joules x 5 strokes (average per strike) = 200,000 joules Are you STILL going to say that lightning doesn't pack a whollop? And why are you totally ignoring the fact that it doesn't matter how much energy lightning may carry, but how much energy lands in the wrong place, which is the REAL issue here? Again, first semester circuit theory that every graduate of West Point and Annapolis has learned. So why haven't -you- learned it? Please first learn that basic circuit theory before disputing IEEE papers, other well proven research, and NEC requirements. Correctly noted is that most people don't climb trees to search for lightning damage to trees. But then researchers such as Alan Taylor of the US Forestry Service are not just most people. Lightning has such low energy that most every tree directly struck has no appreciative damage. Speculate all you want. He did the work and wrote the paper. It's not a matter of speculation. High power doesn't necessarily mean catastrophic damage, especially where nature and the laws of evolution are concerned. Live wood conducts lightning very well, probably due to the fact that lightning happens all the time and trees have had jillions of years to adapt. It has nothing to do with energy, but survival. If every tree was killed by a direct strike, there wouldn't be very many trees left on this earth. Using your reasoning for why earth cannot conduct the electricity even in a badly polluted salt marsh: Whoa, hold on there! I never said ANYTHING of the sort -- in fact I said quite the opposite! A 1 ohm ground rod is damn good, if not impossible! Don't you have ANY practical experience with grounding, either? then obviously lightning could never conduct miles across the sky and obviously lightning does not strike a non conductive earth. Why does air conduct miles of lightning that only contains millions of volts? First learn the many stages of how air and earth become such excellent conductors. Does a cloud strike 5 miles diagonal to connect cloud to charges on earth? Of course not. Lightning travels 3 miles straight down and then 4 miles through earth to complete a circuit. Lightning takes a more conductive path via air and earth rather than an electrically longer 5 mile path only through air. Conductive earth is also why earthing a direct strike (the single point earth ground) is such effective protection from a direct strike. More and more you are demonstrating that you know very little of the subject. While I may not know exact figures as to lightning voltage, current, stroke duration, etc, etc, it's because the differences are insignificant. I just did a little research on my own and found that lightning has anywhere from 1 to 25 strokes per strike, each stroke lasting anywhere from 10 usec to 500 msec, can carry current from 10 to 500,000 amps, blah, blah, blah. The point is that lightning is wonderfully erratic, which I already knew. And here's some more facts: Lightning doesn't always travel straight down (jeez, one would think that you have never seen a thunderstorm before!). Ask any pilot, commercial or private, and they will tell you that lightning can travel many, many miles. There is one case I remember where a stroke came out of the clouds, ran parallel to the earth, over some hills, and seemingly came out of a clear blue sky 20 miles away to strike some little kid riding a bicycle. That's a fact. Lightning isn't very predictable, and certainly doesn't behave according to the rules of the NEC. The sooner you figure that out the better. Because even simple concepts of impedance verses resistance are not understood, then even safety grounds (third prong in wall receptacle) are confused with earth ground. Safety ground is different from motherboard ground is different from chassis ground is different from automobile ground is different from breaker box ground is different from power plant ground is different from earth ground. Most all are interconnected, but are still electrically different. Learn about impedance. No earth ground is found in wall receptacles because the wire length - and therefore impedance - of that third prong wire is just too far from earth ground. Again, one must first understand impedance to appreciate what world renown experts (some quoted here) have said about earthing. You obviously have never wired a house, either. It takes but a few milliamps to kill a human. Does that prove lightning must be a high energy event - because it too kills? Learn how easy a human can be killed before posting such assumptions. Where did I make such an assumption? I distinctly remember posting the following: "The power of a bolt of lightning isn't the big issue here since it doesn't take much power to cause damage. The issue is how well you are protected from whatever amount of power that -does- make it to the surface." So do you have a reading problem (dare I say 'communication deficit')? Even posted is that a buried coax is protected from lightning transients. That is ridiculous as even made bluntly obvious in a Polyphaser application note about damage to an improperly earthed telephone exchange; transient damage via buried wires. You are twisting my words again. I said buried coax provided -better- protection than most other methods. If you don't believe me, go visit a few radio stations. And if you want me to comment on your reference, post the link. Obvious in that long reply - even basic electrical concepts are not understood. Real world professionals and generations of scientific experience prove basic earthing is effective protection. Even the NEC requires OP to earth ground his antenna also for human safety. Basic electrical knowledge - impedance verses resistance - was not even understood and still Frank said everyone is wrong about earthing. Really? Where did I say that? Regardless, I said before that if you want to talk about reactance, we can go there. Do you need me to start? -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
On Sat, 14 Feb 2004 20:36:54 -0500, w_tom wrote:
Lightning builds plasma wires that can short high energy, utility power through other copper wires. Lightning simply creates the short circuit. Then a higher source of energy - AC electric utility - follows to vaporize those copper wires. That point was described by Colin Baliss: Although lightning strikes have impressive voltage and current values (typically hundreds to thousands of kV and 10-100 kA) the energy content of the discharge is relatively low and most of the damage to power plant is caused by 'power follow-through current'. The lightning simply provides a suitable ionized discharge path. Yes direct strikes have caused damage. This was a problem in the early days of ESS-1 - the first electronic switching computers for telephone systems. And so engineers then reevaluated the earthing system in those few 'problem' Central Office buildings to correct the reason for electronic damage - human failure. What is a problem central office building? The telephone companys lose hundreds of "channel unit" boards to lightning damage every year. Most if not all boards lost are in the remote sites, not the central office. The boards that are lost aren't due to human faillure, they are due to the fact you cannot predict lightning, and cannot totally protect against it. Described above is not a best solution. But then a best solution is typically not required. Above described system will not avoid damage from every possible direct strike. But then many of these 'rare' direct strikes have never been experienced by many - maybe most - people. For example, something called hot lightning may discharge the entire cloud in one single strike. It has been observed - just like tornados have been observed (most people also will never witness a tornado in their lifetime). Defined here is effective protection for most direct lightning strikes. It costs so little. To enhance same for the other maybe 1%, serious facilities such as 911 systems, cell phone towers, telephone switch stations, and nuclear hardened maritime facilities spend far more than a few $10. They spend $thousands more on earthing alone just to also protect from the last 1% of worst case lightning strikes. Cell sites have a copper ring of protection around the site. I have been in cell sites that were so totally shielded that my cell phone wouldn't work in them. Everything entering or leaving the site is totally protected. Quite impratical for the normal home owner. I cite nuclear hardened facility especially since a 1998 IEEE paper described a Norwegian maritime station damaged by a lightning strike. They discovered major installation faults in the earthing system for what was suppose to be a nuclear EMP protected station. Faults that even permitted lightning to cause damage. Again, failure directly traceable to a human. Major construction required to repair a simple earthing flaw. Homes contain superior earthing systems that we still don't use today. Ufer grounds could have been installed using existing structure - if planned for when footing were poured. But we still don't install superior earthing systems in new homes 30 years after the transistor existed. Costs to use that Ufer ground on existing homes are now extreme because Ufer grounding was not enabled when house construction started. OP must make do with simple earth ground rods. Properly installed, the Original Poster is quite unlikely to suffer any damage from direct lightning strikes. For but a few $10, he gets a massive increase in direct lightning strike protection. Not perfect. Just a massive improvement. You might want to read up on the damage that has occured when the grounds for a tower were encased in the conctrete base that was the tower mount. They are cases were the lightning "blew" the concrete base up. I don't know which original poster you are talking about. My tower is properly earthed, a direct strike didn't damage my towers or antennas. The induced voltage that got into my network cables is what caused most of my damage. The telephone companies have much the same problem, most of the lightning damage isn't from direct strikes, its from their wireline pick up of induced voltage of a close strike. I think you need to quit reading up on it so much, and spend more time looking at whats practical and proven to work for the CB or ham radio operator. Here is a good place to start: http://lists.contesting.com/archives//html/Towertalk |
On Sat, 14 Feb 2004 20:39:45 -0500, w_tom wrote:
Basic electrical knowledge - impedance verses resistance - was not even understood and still Frank said everyone is wrong about earthing. Frank is 100% correct in what he posted. You have chosen to either not fully read what he posted, or you are having trouble trying to comprehend what he wrote. Take some time and read what others, who have real experience, have written on the subject. |
Learn why 'problem' Central Offices had surge damage - the
problem COs directly traceable to bad earthing in that building due to human failure. But then too many experts don't even know the early 1960s history of ESS-1. How many switching computers did your phone company replace in your town this year - the entire computer damaged by lightning. None. Damage not acceptable in any town, anywhere, any year .... because electronics damage from lightning is that routinely avoided. Lightning damage is routinely traceable to human failure - the technology being that old and that well proven. Cell phone sites do have halo ground. Why? Even the world record lightning strike must never damage an cell phone location. And so they install more than just a copper earth rod. In the meantime that halo ground is not why your cell phone does not work underneath the tower. Properly installed Ufer ground never damage concrete. Human fails - and then blames lightning for the concrete failure? Human is reason for failure. Damage from direct lightning strikes - especially strikes that might damage concrete - are always directly traceable to human failure. Protection from the direct strike is that routine and that easy. Rather than lecture on reading tower talk, instead read about effective lightning protection in tower talk - and why damage from lightning is directly traceable to human failure. You are quoting the wrong source if you think tower talk says lightning damage is unavoidable: http://lists.contesting.com/_towerta...il/004413.html The basic scenario is to install a Single Point Ground System that is installed at the building entry. It shunts everything to ground before it goes in the building. If you can keep it outside, then you don't really have to do much inside. http://lists.contesting.com/_towerta...st/032935.html What you're proposing to do has the makings of what is referred to as a Ufer ground. Named for its inventor, the principle of the Ufer ground is simple. ... according to Polyphaser's "Grounds for Lightning Protection" publication. http://lists.contesting.com/_towerta...er/026083.html An Ufer ground ... this may be the ENTIRE ground system. Since the concrete is conductive and there is lots of concrete area in contact with the soil, it does a pretty reasonable job. Effective protection from direct lightning strikes is routine. Lancer wrote: ... What is a problem central office building? The telephone companys lose hundreds of "channel unit" boards to lightning damage every year. Most if not all boards lost are in the remote sites, not the central office. The boards that are lost aren't due to human faillure, they are due to the fact you cannot predict lightning, and cannot totally protect against it. ... Cell sites have a copper ring of protection around the site. I have been in cell sites that were so totally shielded that my cell phone wouldn't work in them. Everything entering or leaving the site is totally protected. Quite impratical for the normal home owner. ... You might want to read up on the damage that has occured when the grounds for a tower were encased in the conctrete base that was the tower mount. They are cases were the lightning "blew" the concrete base up. I don't know which original poster you are talking about. My tower is properly earthed, a direct strike didn't damage my towers or antennas. The induced voltage that got into my network cables is what caused most of my damage. The telephone companies have much the same problem, most of the lightning damage isn't from direct strikes, its from their wireline pick up of induced voltage of a close strike. I think you need to quit reading up on it so much, and spend more time looking at whats practical and proven to work for the CB or ham radio operator. Here is a good place to start: http://lists.contesting.com/archives//html/Towertalk |
you sound like a real ass
|
On Sun, 15 Feb 2004 12:35:23 -0500, w_tom wrote:
Learn why 'problem' Central Offices had surge damage - the problem COs directly traceable to bad earthing in that building due to human failure. But then too many experts don't even know the early 1960s history of ESS-1. How many switching computers did your phone company replace in your town this year - the entire computer damaged by lightning. None. Damage not acceptable in any town, anywhere, any year ... because electronics damage from lightning is that routinely avoided. Lightning damage is routinely traceable to human failure - the technology being that old and that well proven. Get over yourself, Do you know what a central office is, what a remote is? The switching computers as you call them, never directly see the wireline. Nearly 100% of the damage that the phone companies see is to the channel units in their remotes. They sacrifice the remote channel units to protect the rest of the equipment. That damage cannot be prevented, its expected and accepted. Cell phone sites do have halo ground. Why? Even the world record lightning strike must never damage an cell phone location. And so they install more than just a copper earth rod. In the meantime that halo ground is not why your cell phone does not work underneath the tower. Ok, why didn't my cell phone not work in the site. Hopefully you won't use the word desense. Properly installed Ufer ground never damage concrete. Human fails - and then blames lightning for the concrete failure? Human is reason for failure. Read again, current causes heat, heat expands the moisture in the concrete. Damage from direct lightning strikes - especially strikes that might damage concrete - are always directly traceable to human failure. Protection from the direct strike is that routine and that easy. Rather than lecture on reading tower talk, instead read about effective lightning protection in tower talk - and why damage from lightning is directly traceable to human failure. You are quoting the wrong source if you think tower talk says lightning damage is unavoidable: No, your trying to tell every one that if I earth everything that all damage is avoidable. Its not that simple, proper earthing is very important. Disconnecting antennas, and unplugging Power connections helps complete the protection. No one is telling you that earthing is not important, but it is not the total solution. I have a 500' beverage that I use for the broadcast band. It is earthed a much as a long wire can be. When storms start approaching, its not uncommon for me to see 1/8 arcs across the tuning capacitor. I have news for you, that is more than enough to damage the input to my radio. So I go outside, disconnect my feeds and ground them. http://lists.contesting.com/_towerta...il/004413.html The basic scenario is to install a Single Point Ground System that is installed at the building entry. It shunts everything to ground before it goes in the building. If you can keep it outside, then you don't really have to do much inside. Ok, short of enclosing my wooden structure house in copper, how do I keep induced voltage out? How would earthing have protected my cat5 runs? They are totally inside my house, never enter or exit it. http://lists.contesting.com/_towerta...st/032935.html What you're proposing to do has the makings of what is referred to as a Ufer ground. Named for its inventor, the principle of the Ufer ground is simple. ... according to Polyphaser's "Grounds for Lightning Protection" publication. http://lists.contesting.com/_towerta...er/026083.html An Ufer ground ... this may be the ENTIRE ground system. Since the concrete is conductive and there is lots of concrete area in contact with the soil, it does a pretty reasonable job. Effective protection from direct lightning strikes is routine. Quit trying to pound earthing totally protects you down my throat. There is more to protection then that. |
A person who so poorly protected his own home as to suffer
completely unnecessary computer and TV damage will now teach me? One who even posted the classic urban myth about concrete damage to prove Ufer grounding does not work? You just realized something: someone on the other side does have a few decades of experience and engineering degrees. If you had one, then the concept of resistance and impedance would have been correctly posted. However someone even did read 'tower talk' - and posted citations from 'tower talk' in direct contradiction to your posted myths. Well at least you are not posting personal attacks this time. The world can get better. In the meantime this is a discussion about the OPs antenna mast; not a forum for personal attacks. The OP must earth his antenna mast both for lightning protection AND as required by the National Electrical Code. That answers his question. Please feel free to address the purpose of this thread - the Original Poster's original request for information - Zeeeeeeee3 originally posted: Planning to install a base antenna as soon as things warm up and could use some help.......... So far I have an Imax 99 antenna. I was thinking of attaching it to the garage side of my house which is about~20 feet high at the peak. I would take a 5' piece of antenna mast and pound it several feet into the ground to secure the bottom and then attach 2 more 10' pieces on top of that. The mast could be secured to the house with several of those wall mount brackets. How does this sound so far? Now I understand that it must be grounded. Would having the bottom section of mast pounded into the ground as I mentioned suffice? or will I need to attach it to a seperate 8' ground rod? If a seperate rod is needed, do I attach the ground wire to the antenna mounting plate or the mast or either? Near the top of the mast or near the bottom? I also have read of the need for a 'static discharge unit' for my coax. Could anyone recommend one? Google searches are not helping me out much. Have some more questions, but this seems enough for now. Any help would be really appreciated. I've been trying to piece information together from the web, but still need some more help. Lancer wrote: Frank is 100% correct in what he posted. You have chosen to either not fully read what he posted, or you are having trouble trying to comprehend what he wrote. Take some time and read what others, who have real experience, have written on the subject. |
If Ufer grounds were so destructive, then why does "your"
tower talk even recommend them? You could not even cite appropriate posts in 'tower talk'. Funny. I provided citations from 'tower talk' that says you posted technical inaccurate information. First you deny that earthing is essential for protection. Then you openly admit lightning caused "lost 2 TV sets, 1 computer, my router and wireless access point". Classic damage when all incoming lines are not properly earthed. You have a serious earthing problem in your own home. Instead you cite your own improperly earthed home as proof that earthing is not essential to lightning protection; that no protection is possible. That TV and computer damage is classic when incoming wires - antenna and utility - are not properly earthed. Yes there is more to protection that just earthing. Some incoming utilities require more than just earthing. However without earthing, then no protection exists. Earthing is required at the OPs antenna mast AND on wire as it enters building - the ground block. Earthing is THE first item - the most essential - installed for lightning protection. 'System' installed using concepts in "The Need for Coordinated Protection": http://www.erico.com/public/library/...es/tncr002.pdf No earth ground means no effective lightning (or static) protection. Earthing also required by the National Electrical Code - for human safety reasons. The answer to zeeeeeeee3's original questions: earthing is required at both that antenna mast AND at the common service entrance so that all incoming wires first connect to the single point earth ground. Driving the mast into earth is not a sufficient earth ground. Lancer demonstrates what happens when a poorly earthed home suffers a lightning strike - unnecessary damage to computer and TV. He even denies the effectiveness or need for earthing. That's fine. What is not fine is when Lancer outrightly lies to others about benefits of single point earth ground. For the OP's original question: system demonstrated here applies: http://www.erico.com/public/library/...es/tncr002.pdf Additional products that can utilize advantage of the essential earthing system are offered at Erico, from Polyphaser, and even in Home Depot. 'Whole house' protector is also required on other incoming wires. But the bottom line remains - lightning (and static) protection is only as effective as its earth ground. Earthing is not a total solution. However it is the answer to OP's original question. No earthing means no protection exists and a violation of NEC. Earthing is that essential. In the meantime, even 'tower talk' demonstrates why single point earth ground (service entrance earth ground) and why Ufer grounds are so effective. A preferred earthing solution where people first learn facts before posting denials - and more information for the OP's original question. Lancer wrote: On Sun, 15 Feb 2004 12:35:23 -0500, w_tom wrote: ... Get over yourself, Do you know what a central office is, what a remote is? The switching computers as you call them, never directly see the wireline. Nearly 100% of the damage that the phone companies see is to the channel units in their remotes. They sacrifice the remote channel units to protect the rest of the equipment. That damage cannot be prevented, its expected and accepted. ... Ok, why didn't my cell phone not work in the site. Hopefully you won't use the word desense. ... Read again, current causes heat, heat expands the moisture in the concrete. Damage from direct lightning strikes - especially strikes that might damage concrete - are always directly traceable to human failure. Protection from the direct strike is that routine and that easy. Rather than lecture on reading tower talk, instead read about effective lightning protection in tower talk - and why damage from lightning is directly traceable to human failure. You are quoting the wrong source if you think tower talk says lightning damage is unavoidable: http://lists.contesting.com/_towerta...il/004413.html The basic scenario is to install a Single Point Ground System that is installed at the building entry. It shunts everything to ground before it goes in the building. If you can keep it outside, then you don't really have to do much inside. http://lists.contesting.com/_towerta...st/032935.html What you're proposing to do has the makings of what is referred to as a Ufer ground. Named for its inventor, the principle of the Ufer ground is simple. ... according to Polyphaser's "Grounds for Lightning Protection" publication. http://lists.contesting.com/_towerta...er/026083.html An Ufer ground ... this may be the ENTIRE ground system. Since the concrete is conductive and there is lots of concrete area in contact with the soil, it does a pretty reasonable job. No, your trying to tell every one that if I earth everything that all damage is avoidable. Its not that simple, proper earthing is very important. Disconnecting antennas, and unplugging Power connections helps complete the protection. No one is telling you that earthing is not important, but it is not the total solution. ... |
On Sun, 15 Feb 2004 16:05:10 -0500, w_tom wrote:
If Ufer grounds were so destructive, then why does "your" tower talk even recommend them? You could not even cite appropriate posts in 'tower talk'. Funny. I provided citations from 'tower talk' that says you posted technical inaccurate information. First you deny that earthing is essential for protection. Then you openly admit lightning caused "lost 2 TV sets, 1 computer, my router and wireless access point". Classic damage when all incoming lines are not properly earthed. You have a serious earthing problem in your own home. Instead you cite your own improperly earthed home as proof that earthing is not essential to lightning protection; that no protection is possible. That TV and computer damage is classic when incoming wires - antenna and utility - are not properly earthed. I asked you how I could have prevented my Cat5 from picking up induced voltage, but you somehow avoided that question again. My antenna and utillities are properly earthed. How do you earth a Cat5 cable? Do you know what one is? Yes there is more to protection that just earthing. Exactly what we have been telling you. But some how you want to ignore what others have posted. Some incoming utilities require more than just earthing. However without earthing, then no protection exists. Earthing is required at the OPs antenna mast AND on wire as it enters building - the ground block. Earthing is THE first item - the most essential - installed for lightning protection. 'System' installed using concepts in "The Need for Coordinated Protection": http://www.erico.com/public/library/...es/tncr002.pdf No earth ground means no effective lightning (or static) protection. Earthing also required by the National Electrical Code - for human safety reasons. The answer to zeeeeeeee3's original questions: earthing is required at both that antenna mast AND at the common service entrance so that all incoming wires first connect to the single point earth ground. Driving the mast into earth is not a sufficient earth ground. Are you repeating this for your benefit? If you want to argue with yourself, feel free. Lancer demonstrates what happens when a poorly earthed home suffers a lightning strike - unnecessary damage to computer and TV. He even denies the effectiveness or need for earthing. That's fine. What is not fine is when Lancer outrightly lies to others about benefits of single point earth ground. You put words in Franks mouth, now you are attempting do that with me. I never denied the effectiveness of earthing, I stated and will state it again, sometimes that isn't enough. For the OP's original question: system demonstrated here applies: http://www.erico.com/public/library/...es/tncr002.pdf Additional products that can utilize advantage of the essential earthing system are offered at Erico, from Polyphaser, and even in Home Depot. 'Whole house' protector is also required on other incoming wires. But the bottom line remains - lightning (and static) protection is only as effective as its earth ground. Thought you said Static is irrelevant. A few hundred volts of static will not damage any properly built radio. You could even static shock your car radio antenna or a portable radio antenna without damage. That would be as much as 18,000 volts - and still no damage. Earthing is not a total solution. However it is the answer to OP's original question. No earthing means no protection exists and a violation of NEC. Earthing is that essential. No one has said any different. Glad that you admit earthing is not the total solution, something I have maintained all along. In the meantime, even 'tower talk' demonstrates why single point earth ground (service entrance earth ground) and why Ufer grounds are so effective. A preferred earthing solution where people first learn facts before posting denials - and more information for the OP's original question. Great, why don't you do that, and get over the idea that earthing is not the total and complete solution. |
| All times are GMT +1. The time now is 05:06 PM. |
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com