| reply to Jack_in_VA
Re: question for our electrical experts said by Jack_in_VA:Ok just what any average homeowner would install at their homes..... Well, no. But I have a couple of large lightning rods in my back yard. I figure the worst case if something gets damaged I can tell the insurance co, "hey, well at least I tried."
I guess the tv transmitter tower I used to watch get eat up with it's massive professionally designed ground system was at the same potential 100 percent of the time? (NOT) at times it was knocked off the air until repairs could be made. That may be why it was moved to an area that it was not the highest structure.
W8JI has a large contest amateur radio station out on an old cow farm in Georgia. I took most of my grounding lessons from him. His towers get hit every year, he estimates about 8 times. He suffers little damage. |
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| reply to garys_2k
said by garys_2k:said by Draiman:said by garys_2k:I'm skeptical of the direct strike/nothing happened thing, too. That's better than places with $100K grounding systems sometimes do.
Assuming they installed the $100k system correctly? Even the best system is only as good as it's weakest link.  Yes, even then. Multiple ground rods with bonding cables between them forming a perimeter loop, plus bonding to a single point of the foundation re-bar, PLUS isolating the internal equipment from the floor with 20K volt insulators PLUS equipotential interior grounding perimeter conductors sometimes still allow damaging surges to penetrate from a direct strike. Direct strikes, particularly from positive lightning, can defeat properly installed, professionally designed protection systems. If it really was possible to totally protect them then we wouldn't have electric utility or broadcast systems disrupted from direct strikes. Well, yes. But direct strikes CAN, doesn't mean they WILL. You can protect against them. Don't think you're helpless at all. The goal is to minimize damage. |
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 PSWired
join:2006-03-26
Annapolis, MD | reply to themagicone
This forum is not where you'll find answers for this. You'll be best off talking to an electrical engineer who's familiar with designing lightning protection for high-exposure outdoor electronic systems. Lately the discussion here seems to be limited to irrelevant anecdotes with far too little background information.
It's indeed done all the time for highway cameras, weather stations, radio transmitters, etc. Surviving direct strikes is possible (but never guaranteed) with the proper engineering.
The engineer you speak with will focus on providing a low-impedance path for the lightning current to take to ground, and designing the power/signal paths so that they aren't effective for lightning current to flow through.
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 Jack_in_VAPremium
join:2007-11-26
Mathews, VA
kudos:1 | quote:
Surviving direct strikes is possible (but never guaranteed) with the proper engineering.
Exactly
A couple of weeks ago lightning got the Directv up-link for the Hampton Roads local stations. Off air with their local tv signals over 24 hours and longer for the HD signals. Thank goodness I stll have my UHF outdoor antenna so I could get them OTA. |
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 nunyaWho is John Galt?Premium,MVM
join:2000-12-23
O Fallon, MO
kudos:8
 ·Charter
 ·surpasshosting
| reply to themagicone
If you get the chance, get the Soars book on grounding and bonding from your library. Also see if they have the IEEE "Green Book".
These two sources are invaluable. Even when I worked for Ma Bell, who self published EVERYTHING technical, they would still buy the "Green Book". Most (not all) of the practices on cell sites are taken from this publication.
Having worked in the communications (wire and wireless) and electrical industries for my entire career - I've learned a lot about lightning.
Some of the key things I've learned:
Doing nothing is stupid and irresponsible.
Sites with comprehensive bonding, grounding, and lightning mitigation suffer far less damage.
You can't stop every strike. Lightning will do whatever it wants. We can only offer it suggestions.
At 50,000 degrees and 300,000 amps, the laws of physics, as we know them, bend. We (the human race) still don't know exactly what forces are taking place at the exact time and location of a strike. We have a real good idea, but we don't know everything.
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...because I care. |
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Jack_in_VAPremium
join:2007-11-26
Mathews, VA
kudos:1 | +1 |
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| reply to Jack_in_VA
said by Jack_in_VA: quote:
Surviving direct strikes is possible (but never guaranteed) with the proper engineering.
Exactly A couple of weeks ago lightning got the Directv up-link for the Hampton Roads local stations. Off air with their local tv signals over 24 hours and longer for the HD signals. Thank goodness I stll have my UHF outdoor antenna so I could get them OTA. I think I know an engineer who worked at one of the local FOX stations up your way. |
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| reply to nunya
said by nunya:If you get the chance, get the Soars book on grounding and bonding from your library. Also see if they have the IEEE "Green Book".
Also helpful is the Motorola R56 manual which is the standard for wireless facilities such as cell sites. It is based on several ANSI standards |
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Jack_in_VAPremium
join:2007-11-26
Mathews, VA
kudos:1 | reply to fifty nine
Lintv owns the Fox Ch 43 and the NBC Ch 10 stations in Hampton Roads. Les Garrenton (sp) was promoted to chief engineer for all of Lintv's stations around the country. A very nice, knowledgeable man. He was instrumental in getting the station on in HD with all it's problems. |
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 49528867Premium
join:2010-04-16
Fort Lauderdale, FL
kudos:3 | reply to UHF
said by UHF: I learned from working on cell sites which were designed by actual electrical engineers and the differences in grounding there compared to the typical broadcast tower were amazing. I did contract engineering for Jefferson Pilot (now Lincoln Financial) on the AM side 790 WNWS/WAXY and the transmitter site was out in the east Everglades in other words the antenna array was the tallest thing for miles and during the rainy season took direct hits almost on a daily basis and it was extremely rare for a hit to take us off the air, usually all the bad hits did was take out a PA module in the Nautel causing the transmitter to raise the power to the remaining modules to make up for the one that went out of service.
Needless to say the chief engineer of the cluster John Morris was nothing less than a master when it came to designing systems to be lightning proof.
Wayne
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Madness takes its toll, please have exact change ready… |
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Jack_in_VAPremium
join:2007-11-26
Mathews, VA
kudos:1 | Jefferson Pilot engineering did a terrible job with WWBT-TV in Richmond, VA. Especially with the analog to digital transition. It's owned by Raycom now who seems to be doing a much better job. |
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49528867Premium
join:2010-04-16
Fort Lauderdale, FL
kudos:3
1 edit | reply to fifty nine
said by fifty nine:I have had direct strikes on my ham radio tower and nothing damaged. Same here, in 2010 I took a direct hit to my tower that reduced what once was a fiberglass encased 12 foot collinear VHF antenna down to is aluminum mounting base.
There was nothing left of the actual antenna that was within the fiberglass radome and only few small shards of the radome could be found scattered around the yard, and as I discovered after I replaced the antenna the hit also did something to the feedline between the ground mounted coaxial surge protector and the antenna, the feedline measured good DC wise but appeared as an open to RF.
As for damage to any equipment inside the home nada none at all.
However I do have some righteous ground and bonding around here, this is the ground for the tower which in turn is bonded to my homes ground ring.
And this is the coaxial surge protector.
Wayne
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Madness takes its toll, please have exact change ready… |
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49528867Premium
join:2010-04-16
Fort Lauderdale, FL
kudos:3 | reply to Jack_in_VA
said by Jack_in_VA:Jefferson Pilot engineering did a terrible job with WWBT-TV in Richmond, VA. Especially with the analog to digital transition. Thats what they get for not hiring me. 
Wayne
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Madness takes its toll, please have exact change ready… |
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Jack_in_VAPremium
join:2007-11-26
Mathews, VA
kudos:1 | said by 49528867:said by Jack_in_VA:Jefferson Pilot engineering did a terrible job with WWBT-TV in Richmond, VA. Especially with the analog to digital transition. Thats what they get for not hiring me. Wayne Could be. Rumor was they were very tight fisted. They even reused their existing tower by getting permission to stay on VHF channel 12 while all the other stations built an antenna farm and clustered their transmitters. This is still causing a lot of problems with reception OTA. |
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49528867Premium
join:2010-04-16
Fort Lauderdale, FL
kudos:3 | said by Jack_in_VA: Could be. Rumor was they were very tight fisted. Same down here, hence the reason we parted company, it’s becoming SOP in broadcasting that the engineering department is seen as a pariah even though they keep the place on-the-air and without being on-the-air the kings of the castle, marketing, would have little to do and all day to do it.
Wayne
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Madness takes its toll, please have exact change ready… |
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garys_2kPremium
join:2004-05-07
Farmington, MI Reviews:
 ·callwithus
·Callcentric
| said by 49528867:said by Jack_in_VA: Could be. Rumor was they were very tight fisted. Same down here, hence the reason we parted company, it’s becoming SOP in broadcasting that the engineering department is seen as a pariah even though they keep the place on-the-air and without being on-the-air the kings of the castle, marketing, would have little to do and all day to do it. Wayne That is true of a LOT of businesses, I'm afraid. The infrastructure is low on the list of things to take care of. |
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garys_2kPremium
join:2004-05-07
Farmington, MI | reply to 49528867
Wayne, was that surge protector directly, physically under the antenna or was it back upstream of (some of) the feed line? |
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49528867Premium
join:2010-04-16
Fort Lauderdale, FL
kudos:3 | said by garys_2k:Wayne, was that surge protector directly, physically under the antenna or was it back upstream of (some of) the feed line? It was installed at the base of the tower about 40 feet from the antenna.
Wayne
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Madness takes its toll, please have exact change ready… |
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garys_2kPremium
join:2004-05-07
Farmington, MI | Clearly you did a great job of lightning protecting your equipment and likely prevented lot$ of damage to the stuff in your house (ham gear and everything else). |
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 John GaltForward, MarchPremium
join:2004-09-30
Happy Camp
kudos:5 | reply to 49528867
said by 49528867:...it's becoming SOP in broadcasting that the engineering department is seen as a pariah even though they keep the place on-the-air...
QFT |
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