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Author Topic: Safe operation during a lightning storm  (Read 3963 times)
K8AXW
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Posts: 3910




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« Reply #15 on: April 29, 2011, 10:01:27 PM »

Prior to installing my little 50' tower I read a great deal and asked a lot of questions, especially about lightning protection.  I had learned that the tower should be well grounded but an additional piece of information was supplied by an old electrical engineer.  He said, "Al, just remember when you install the lead from the tower to the ground rod(s), lightning doesn't like to go around corners!"

In other words, make any lead attachments with sloping curves, no bends!

Then again, he's the same engineer that patiently listened to me bitching about having to change generator brushes on the fly and then said, "Don't worry about it Al, we expect to lose an operator once in a while."
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K6AER
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« Reply #16 on: April 30, 2011, 09:09:04 PM »

I wish E-Ham would just install a front page tutorial on station grounding. I would save time and space.

There is a lot of myth about lightning. Lightning basics are not hard to understand and once you learn them the subject becomes much easier to understand.

Commercial antenna installations are constructed following standard lightning protection procedures to mitigate surge potentials. These practices work 99.99 % of the time. Sprint has over 190,000 cell sites and we would lose less than 5 sites a year to lightning. Calculations based on samples indicated we would have over 30,000 site strikes a year. Proper surge protection works very well but there are no short cuts.

Lightning can travel several miles from a charged cloud to the earth when the voltage potential between the cloud and earth can ionize a carbon path for the discharge. If this ground potential is through a house then you will get struck. If your tower presents a greater ground potential then the tower gets struck. If power lines get struck and the lowest impedance connection can be through your AC panel via your ham station, LCD TV, home appliances to the wonderful tower ground you will experence damage.  Without an AC panel surge protector, all the home electronics gets fried. Depending on the severity of the strike, several paths can provide a surge path to earth ground.

I have been struck quite a few times and each time the lighting protection procedures put I place have saved the equipment. I have lost fiberglass antennas and have had surge protectors welded short but the hamster equipment was saved.

Lighting surge applications cannot be done half way. A complete and compressive system must be employed for successful surge mitigation.

Please visit the article listed below for more surge protection information. Read the tutorials at Polyphaser.

http://www.eham.net/articles/13461

Prepare your station for the strike.

73, Mike
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KD4LLA
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Posts: 462




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« Reply #17 on: April 30, 2011, 09:39:34 PM »

Just curious; How do 300 foot tall cell towers,TV and commercial radio stations all stay on line during lightning storms ?
73 Jim. KF5HRN
I don't know and I don't care.  I live in a 80 year-old house in the country.  Not disconnected any antennas ever.  If lightning strikes it will burn/blow the house and whatever is in it.  There will be nothing left of my house if I take a near direct/ or direct hit.  I just keep the insurance up to date.

Most folks just worry too much.  There is a grounding question once a week here on eHam.  And the only answer clear to me is either go all the way like the commercial towers or nothing at all.
   
Do sprinklers save a library and books from a total loss fire?

Mike
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KD4LLA
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« Reply #18 on: April 30, 2011, 09:42:45 PM »

I wish E-Ham would just install a front page tutorial on station grounding. I would save time and space.

Wouldn't do any good.  There is tons of info out there about grounding and folks would still be asking the same questions...  I try my best to avoid the subject.

Mike
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K9KJM
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Posts: 2415




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« Reply #19 on: April 30, 2011, 11:10:26 PM »

Good info from K6AER.

It DOES take some effort to properly protect a station. It CAN be done on a budget. For tips on how see:


http://www.scribd.com/doc/14868226/lightning-protectiontaming-thors-thunderon-a-budget

(Give that site plenty of time to load.)

Here is another link with some good info:

http://www.bidstrup.com/w7ri-lightning-grounding-rfi.htm

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KE4JOY
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« Reply #20 on: May 01, 2011, 07:47:02 AM »

Do sprinklers save a library and books from a total loss fire?

Mike

Just thought I would note...

Libraries which contain valuable tomes do not use sprinklers. Rather they rely on gas fire suppression systems.

http://en.wikipedia.org/wiki/Gaseous_fire_suppression

Just did one for the university here not to long ago.
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AC5UP
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Posts: 3908




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« Reply #21 on: May 01, 2011, 09:58:50 AM »

Libraries which contain valuable tomes do not use sprinklers. Rather they rely on gas fire suppression systems.

Which makes sense as a small fire could result in 50 books damaged by fire and 3,000 damaged by the sprinkler system.  Wink

BTW: Here's an interesting piece of video captured by a surveillance camera: http://www.lifeslittlemysteries.com/lightning-strike-survivor-video-real-fake-1623/ Watch closely to see if you can tell which one of the people in the video is a Heathshkit owner!
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K8AXW
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Posts: 3910




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« Reply #22 on: May 01, 2011, 12:42:07 PM »

OK, so someone asks about lightning every week here on eHam.com!  So?  That, to me, is quite understandable.  The number of articles written about lightning and how to minimize its damage would comprise a library of its own. 

Lightning is one subject, along with "what's the best linear to buy" that brings out what I call "CGS" or computer Geek Syndrome in people.  Have you paid any attention when two computer geeks get together?  It is a constant oneupmanship conversation.  They can't help it! 

Of the dozens of articles and books I've read on lightning and lightning protection, I've read only two or three that explains things in terms that the average ham can understand.

THIS is why you'll find the same "lightning questions" on eHam.com every week!  It was suggested that someone should write and publish an article here about lightning and lightning protection.  I agree 100%.... but KISS.
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KE4JOY
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Posts: 1381




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« Reply #23 on: May 01, 2011, 05:03:29 PM »

Watch closely to see if you can tell which one of the people in the video is a Heathshkit owner!


The well grounded one of course !  Cheesy
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WA9SVD
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Posts: 2198




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« Reply #24 on: May 03, 2011, 07:22:24 AM »

There are two issues to consider.

    The first, is that if your home is directly hit, even an "indoor" (attic, etc.) antenna and equipment may well be severely damaged.

    However, even if a a nearby location receives a lightning strike, there CAN easily be damaging impulses induced into even indoor antennas!  So grounding is an important consideration, even for indoor antenna installations.
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