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Lightning Safety

Created by Larry Kendall, K5END on 2008-07-22

Lightning Safety

Lightning-human encounters cause burns, trauma and electrical interference with physiological processes, often with fatal results. This article addresses personal safety concerns with lightning. Antenna and grounding practices are covered quite well in recent QST articles as well as ARRL and other literature and are therefore not iterated here. Lightning protection for backpacking and blue-water sailing are not covered comprehensively in this article.

The following three points are important.

Big Point 1: The first strike of lightning in a thunderstorm is just as deadly as the last. For some reason, people tend to dismiss the danger of lightning for at least the first few strikes. Electrical storms don't have to "warm up" to be deadly. If you can hear thunder, you are vulnerable immediately. Seek shelter.

Big Point 2: A tree is a poor choice for shelter. Lightning striking the tree will flashover in a deadly penumbral shape around the tree as it seeks paths to ground. Secondly, the tree sap will boil and turn to steam rapidly, exploding the trunk of the tree. This is a bad place to be when it happens.

Big Point 3: Lightning is second only to floods in terms of "natural" fatalities. Fear lightning more than earthquakes, tornadoes, wildfires or volcanoes. In the United States, Florida has the highest frequency of lightning events; lightning in Alaska is rare.

LIGHTNING BASICS

Lightning is the plasma path that allows charge equalization between the atmosphere and the ground or between regions of the atmosphere. This process is nearly continuous worldwide. The process of lightning path generation as a plasma wave forges its way through the air is both fascinating and esoteric. Air does break down under electric fields and lightning occurs. That is what matters.

A lightning strike is a "current source" and is effectively independent of load impedance. Call it an electrical Tsunami. You can neither stop it nor out run it. Protect yourself as you would from a Tsunami: stay out of its path!

A lightning strike is composed of several strokes as various charged regions are equalized. Stroke "leaders" may originate and extend from cloud to ground, ground to cloud or cloud to cloud. You can observe the individual strokes in the duration of a single strike especially well if at a distance when wind across the ground is significant where the strike occurs. The paths shift slightly with the wind during the series, giving the appearance (to human visual perception) of "ribbon lightning." Strokes often fork into diverse paths as the charge finds the most efficient routes toward equalization.

Yes, Virginia, lightning can strike the ground where the sky overhead is clear and blue; thus the expression, "out of the blue." Lightning can travel horizontally for miles before striking the ground. If you can hear thunder, you are within range of a strike.

Cloud-to-ground voltages range from 100 million to 1 billion Volts.
Typical peak current is 30,000 Amperes. This means that only 0.0000033 of the electrical current in a routine lightning strike is lethal.
Typical length of a lightning path is 5 kilometers.
The short time domain of a lightning stroke means that a large bandwidth is conducted and radiated as energy. This is why lightning static noise is present everywhere across the radio bands. It is less noticeable on FM modes, but it is still there on the bands (lightning is noticeable on FM broadcast mostly as "dead air" when their transmitter/antenna takes a strike!) What does this mean to us? It means that the protective grounding configuration must account for and have minimum impedance for all frequencies from DC to UHF.

Power of a single lightning strike:

Visible light 1-3%

Sound >10%

Heat <50%

Radio waves <50%

Duration ranges from 0.001 to 0.5 seconds.

The region around a ground strike will cause a voltage gradient in the top two feet or so of the soil until the current is dissipated. Persons standing with feet spread or laying on the ground are at increased risk. (Anecdotally, it is claimed that cattle die when the poor heifer's axis is aligned with this gradient. Who knows?)

Shrapnel from objects disintegrating near a ground strike is another common source of injury, especially in rocky areas.

LIGHTNING PROTECTION

The best defense to lightning is to seek safe shelter within an ENCLOSED structure, which means you need to be aware of the weather and have a plan beforehand. For example, any boater who finds himself in peril on a lake when a thunderstorm emerges needs to work on his situational awareness, if not consider another form of recreation. Think ahead and plan. The human species supposedly became more intelligent as a result of the last ice age. Those who were able to plan ahead were the ones who survived!

Buildings which are NOT SAFE are those with exposed openings. These include beach shacks, picnic shelters, pavilions, carports, and baseball dugouts. Porches are especially dangerous.

Once inside a suitable building, stay away from electrical appliances and plumbing fixtures. Lightning can travel great distances through power lines, especially in rural areas. This means a distant storm poses a risk inside your home, especially in the absence of proper grounding. Electrical appliances pose a risk to the user, ESPECIALLY corded telephones. Computers are also dangerous as they usually are connected to an ISP facility and the house AC. It should be obvious this is not the time for a shower, bath or a hot tub party.

An enclosed metal vehicle makes a good shelter. When lightning strikes a metal car, it is conducted through the car's metal structure and then arcs to the ground, at the easiest point and usually from the axle to ground. Aftermarket (ham) antennas may compromise the safety within a vehicle. Roll the windows up (glass is a pretty good inhibitor to plasma) and avoid contact with any conducting paths leading to the outside of the vehicle. Keep in mind that tornadoes often coincide with thunderstorms, and a car is not adequate shelter from a tornado.

Don't fall prey to the urban legend: the myth of tires. The tires have nothing to do with lightning safety. A car is safer because you are surrounded by a conductor, and Gauss's law, #1 in Maxwell's 4 famous collective equations is a good source to find an explanation of why this matters. In short, the voltage drop from the top of the car where the lightning hits to the floorboard where your behind is planted is enough protection to keep the air inside the vehicle from ionizing and providing a path for the lightning. BUT, I wouldn't go raising my hands to the headliner to test the protection factor! The "myth of tires" is pointed out here because of the following unsafe vehicles. Convertible (or fiberglass) vehicles offer little safety from lightning, even if the top is "up". Other vehicles, which are NOT SAFE during lightning storms, are those, which have open cabs, such as golf carts, tractors, and construction equipment. Motorcycles do not offer adequate protection from lightning.

Water or material on the surface of windows may heat with rapid steam generation or flashover conduction and cause the glass to shatter. Be aware of this possibility. This author is not aware of documented examples of this, but includes it as a possibility and recommends facing the interior of the car or building during shelter from an intense electrical storm.

Use the "30/30 rule." If the interval between the light flash and the thunder is less than 30 seconds, seek shelter and remain sheltered for 30 minutes after the last strike of the storm. "Counting seconds" is not an accurate method to estimate lightning distance! The speed of sound is dependent on air density and other factors, and there is no accounting for triangulation. Note that thunder may be a rumble rather than a sharp report. This is because the observer would be hearing various regions of the lightning path, all of which travel varied distances at the speed of sound, which also varies. A sharp thunder report implies the site of the ground strike is nearby, nothing more.

For outdoor activities:
The first outdoor procedure is to get indoors. Recreational pilots have a saying about weather. "It's better to be on the ground wishing you were flying than to be flying and later wish you were on the ground." The same logic applies to lightning. Know the weather forecast before you venture outside.

HAVE A PLAN and make sure the responsible party members understand the plan. Designate individuals to monitor the weather.

Know safety shelters in advance.
Designate individuals to organize and lead evacuation.

This practice will save softball, little league and soccer players. Better to forfeit the game or skip the practice than to die for no reason at all. If the coach is not compliant, don't let him reduce your life expectancy or that of your child. Write him off to Darwin. Few will remember the outcome of the game for very long. The death will be remembered for much longer.

Golfers, listen up! Think about this. You're standing in wide open spaces, you are the tallest objects in the vicinity, you installed metal electrodes on your shoes (damp leather against your feet) pressed into the damp earth, and you're swinging a pretty fair "lightning rod" (carbon graphite can conduct too!) several feet above your head, if not holding an umbrella constructed with "pointy-ended" (perfect for coronal discharge initiation of a ground leader!) metal ribs extending a couple of feet in all directions. Call it a day, go inside, have a "beverage" and tell war stories (which is probably the important part of the outing anyway. Am I right?)

Backpacking and hiking require special instruction beyond the scope of this article. But in short, get off the ridges, spread the group out and stay away from the trees. Minimize your footprint on the ground; it would be better to squat with feet together, rather than lie flat. The group members should spread out considerably so that a strike would affect fewer members and the other members would still be able to apply first aid and begin medical evacuation.

Bicyclists, head for the nearest shelter or take cover. Stay aware of the weather and have a plan. If thunderstorms are predicted, consider whether you should ride another day.

Remember:

1. Lightning is an everyday killer across most of the United States.

2. The best protection from lightning is to stay out its path by seeking shelter.

3. Become informed and have a plan.

N6HPX 2008-08-08
RE: Lightning Safety
Whenever I disconnect mine I set the coax outside the room as I read in Popular Electronis years ago that it could still jump acroos the room even while disconnected to your rig and anything else in it. So I been doing just that and put the wire in an area that if the antenna does take a hit it won't hurt someone in the process. Just a little food for thought and it might be good advise.
KV1M 2008-08-06
RE: Lightning Safety
A good friend of mine, N9XR, just got hit a couple of weeks ago.
I understand he had disconnected his gear yet a direct hit in his antenna still took out his rig, his computer and nearly got him in the process.

Be careful, if you see the flash and hear the rumble it's best just to get out of the shack for a bit.
N6HPX 2008-08-03
RE: Lightning Safety
I remember a Police officer close to where I use to stay who refused to get out of his vehicle cause of the lightning coming down in the area he was in due to severe strikes he felt safer inside the car than outside and was using a handheld radio rather than his vehicle as he was in fear of a strike. Just something to think about.
W3END 2008-08-01
Lightning Safety
Very good information thanks
K5END 2008-07-28
RE: Lightning Safety
It was obvious you were kidding, but it's still an interesting question worth answering.
K2WH 2008-07-28
RE: Lightning Safety
I hope you guys know I was kidding. It just popped into my head.

K2WH
W4LGH 2008-07-28
RE: Lightning Safety
Can you imagine what was going thru Faraday's head when he decided to test out his theory?

I sometimes wonder about the true intelligence of some of those people. Ben Franklyn for one, flying a Kite in a thunderstorm, with a wire hooked to it!

Kinda reminds me of a theme song we've all heard....
"WooHoo, WooHooHoo"
K5END 2008-07-27
RE: Lightning Safety
"Question: If I wear a typical scuba wet suit (head to toe) and wrap myself in tin foil with a small metal window screen for my eyes (so I can see), would this make it OK for me to walk outside in a thunderstorm? "

You'd be better off in a drysuit inside a shark cage.

:-)

OK, I'll treat it like a fair question.

Let's examine why what you describe would still be dangerous.

1.) The foil would likely be too thin to withstand the current. Therefore your "shield" would be destroyed before it does its job.

2.) The foil would be poorly bonded on the wraps. Even if it were one, continuous wrap, the reactance would lead to problems.

3.) Foil tears too easily, leaving you vulnerable.

4.) Rainwater would seep into your costume. Guess what happens then. Based on the assumption that you're wearing a standard neoprene wetsuit, which often has nylon fabric either on the outside, inside or both. That webbing soaks up water. Then your skin is now part of the Faraday shield. Purpose defeated.

5.) Even if you avoided electrocution of a lighting strike, you'd still get cooked by RF burns and direct thermal "burns." Your skin would not burn. More likely the flesh would burst open as your blood is boiled and turned to steam. Most high-voltage victims lose a hand or a foot this way, even if they survive.










W4LGH 2008-07-27
RE: Lightning Safety
K2WH siad..."You say a car is good place to be due to the metal skin of the car. A faraday shield.

Question:

If I wear a typical scuba wet suit (head to toe) and wrap myself in tin foil with a small metal window screen for my eyes (so I can see), would this make it OK for me to walk outside in a thunderstorm?"


I say...give it a try and find out. Be sure to find the highest place to stand!

Nature does have its own way to weed out the weak, and allow the strong to survive. Week and strong also applies to intelligence too!

And...they do say that which does NOT kill you, will make you stronger! So...Go for it and let the rest of us know! If we don't hear from you, we'll know what happened!

Snap, Crackle, Pop!

73 de W4LGH - Alan
http://www.w4lgh.com

AD5TD 2008-07-27
RE: Lightning Safety
"You say a car is good place to be due to the metal skin of the car. A faraday shield.

Question:

If I wear a typical scuba wet suit (head to toe) and wrap myself in tin foil with a small metal window screen for my eyes (so I can see), would this make it OK for me to walk outside in a thunderstorm?

K2WH"

There always must be one smart ass in the group...
K2WH 2008-07-27
RE: Lightning Safety
You say a car is good place to be due to the metal skin of the car. A faraday shield.

Question:

If I wear a typical scuba wet suit (head to toe) and wrap myself in tin foil with a small metal window screen for my eyes (so I can see), would this make it OK for me to walk outside in a thunderstorm?

K2WH
N6HPX 2008-07-26
RE: Lightning Safety
For me I just disconnect all the antennas and telephone cables better safe than sorry later as I get these storms every day. I use the cellphone instead
KG2V 2008-07-25
Lightning Safety
RE - Not a good time to surf the web:

In this day and age of laptops and wireless routers, it can be a fine time - just don't ahve the laptop plugged into anything. No charger connection, no lan connection, it's a good way to occupy time
AA4PB 2008-07-25
RE: Lightning Safety
Here's some info on ball lightning.

http://www.usatoday.com/tech/columnist/aprilholladay/2004-07-30-wonderquest_x.htm?loc=interstitialskip
K5END 2008-07-25
RE: Lightning Safety

Hi, Alan.

A lightning stroke is not really A/C but is a pulse function. And, Fourier analysis reveals a large number of sinusoidal components at different wavelengths and amplitudes comprising the function. The sum of those components to represent the function of the lightning event is the principle of "superposition."

Examples:

Our human auditory perception is based on this in part. The musician's ear is trained especially well in this regard and can therefore tell you the individual notes in the more complex chords that are heard in jazz. C&W on the other hand does not require that level of training, as it is very, very simple, musically. Those who have not had the luxury of training their brains to interpret the more sophisticated music will not be able to appreciate it. Anything the brain cannot interpret is defaulted as noise. That's why the musically untrained typically have the identical criticism of jazz or classical music, "it all sounds the same." To them it does! Try putting a "minor-7th-suspended" chord in country music sometime and see what happens. (The universe might tear, so please do not attempt such a reckless act.)

In a large restaurant there may be many conversations. Exceed ones ability to resolve that many individual conversations and it begins to sound like noise only.

Also, the old fashioned analog modems sound to the human ear like white noise, when in fact it is composed of several tones changing rapidly. The ear is not programmed to isolate and understand the tones as such.

Anything from a lightning event to a square wave or the timbre from a clarinet can be broken down this way into the frequency components. This why a note on a piano sounds different than the exactly same note on a trombone.

This is basic stuff in physics and EE.

As a rule, the shorter the signal, the larger the spectrum needed to accomplish the function. The extreme case is a Fourier transform of the Dirac delta function. Do the math and you will see what I mean.

This is why you can hear the lightning "static" noise anywhere on the RF bands you choose to listen. It sounds like noise and not like harmonious waves because of the magnitude of spectral components. It is called "static" because it is noise caused by discharge of static electricity.

Lightning emission exists beyond RF. It also emits infrared, visible light, UV and even some X-rays.

The RF spectral distribution of a lightning strike will be represented by a Fourier transform of the time domain function and limited to the RF region of frequency space. Your statement may be too broad. Who determined that lightning RF is weighted at 1070 KHz as you stated? I would enjoy reading that publication.

A lightning event, which one may refer to as a strike, can originate from ground to cloud, cloud to cloud or cloud to ground. A strike is not a defined scientific term. A "stroke" is more specific and more than one stroke usually occurs with a specific lightning strike.

It begins with stroke leaders forming the path of least natural resistance through the atmosphere. They typically originate from both ends of the event. When the stroke leaders connect from end to end, usually meeting somewhere between the endpoints, a stroke occurs. Several strokes can follow during a single lightning "strike" as different regions of space equalize their charge distribution.

Flashover is a phenomenon when current does not flow through an object, but instead follows its surface or the near region of space.
W4LGH 2008-07-25
RE: Lightning Safety
There are a lot of mis-truths about lightning. One is a lightning Strike, when in fact, lightning does NOT strike anything. What you see is a "Flash-over" as a result of 2 paths crossing. The second one, Lightning will always seek its path to ground. One side of the flash you see is Ground, it doesn't have to seek it. The third one is grounding for lightning. This simply can not be done, as lightning is not DC, it is more like a combo of AC and RF. It is made up of MANY different frequencies, making it impossible to "so call" ground it. The purpose of using grounding material, is to divert as much of the energy of the lightning flash away from what you are protecting, and dissipating it into the ground.

There are many other ways to protect yourself and property from the damage of lightning. Faraday shields, Halo systems, Air terminals, or lightning rods. This type comes in many different forms, like "bottle brush configuration", this has many spikes pointing up into the sky, and the idea is, more surface area. The "umbrella" is another configuration which increases the surface area, and has a capacitance effect with the atmosphere, and generate more up-streamer.

The forth and last in my series, is lightning will ALWAYS strike the highest point. While this is true in most cases, it simply is NOT the case every time. Since we already know that lightning does NOT strike, its a case of where the most, or strongest up-streams are.

As I said earlier, Lightning is AC and contains RF. Most of the RF in lightning is LOW Freq. and has been determined to be around 1070Khz. This is right in the middle of AM Broadcast freqs., but since most portable AM radios are, just that AM, you can not hear these up-streamers. If you added a BFO, or injected a weak carrier just off this freq., you can in fact hear these up-streams, and you can hear them as they get stronger and higher in frequency, until such time as you have a flashover. I have done this, when working several am broadcast stations, and could tell when the flash was going to happen. If the signal is very strong, I would suggest vacating the area as fast as possible, as you could be in immediate danger. You can also tune this freq in on your HF radio, using lsb, and hear this, if they are close enough. Give it a try sometime, but it WILL scare you, knowing when its going to flash.

73 de W4LGH - Alan
http://www.w4lgh.com

K5END 2008-07-24
RE: Lightning Safety
That sounds a lot like the so-called St. Elmo's fire, a coronal discharge first named by sailors who observed plasma at the ship's mast head.

Some folks believe that ball lightning is SEF.

There are also some pretty good theories that ball lightning is merely a human perception event arising from any number of physiological explanations.

My opinion is that more than one phenomenon is viewed as "ball" lightning, and Saint Elmo's Fire is just one that is regarded as ball lightning.

******************************************

Aside from Saint Elmo, each "Tickle Me Elmo" doll manufactured had to pass TWO quality assurance "test tickles" which should not to be confused with "ball" lightning.
KA1MDA 2008-07-24
RE: Lightning Safety
I think I may have seen ball lightning once- always wondered about it. Was during a thuderstorm about 30 years ago. I was looking out of my second story window, when I noticed what looked like a 3-4 foot diameter glowing ball with a green tint appear on one of the 115KV high voltage lines which ran along the oppisite side of the street. The ball seemed to be centered on one of the wires, and moving along the wire quite slowly, maybe about 10-15 miles/hour. When the ball reached the insulator at one of the steel support towers, it made a loud pop and exploded into a shower of sparks. Was this ball lightning???

73, de Tom, KA1MDA
www.ka1mda.org
K5END 2008-07-24
RE: Who is really IN CHARGE ?
"N4FOZ That, folks, is what I call an excellent article!"

Thanks, Mike.

****************************

"AC0GR 'Water or material on the surface of windows may heat with rapid steam generation or flashover conduction and cause the glass to shatter. Be aware of this possibility. This author is not aware of documented examples of this, but includes it as a possibility and recommends facing the interior of the car or building during shelter from an intense electrical storm.'
Here is some documentation to consider. :)
http://www.freerepublic.com/focus/f-news/1397994/posts"

Thanks, Paul.
I'd always believed this result was possible.
That's what I call empirical proof of a theoretical prediction. :-)
Thanks for the verification.

AC0GR 2008-07-24
RE: Who is really IN CHARGE ?
"Water or material on the surface of windows may heat with rapid steam generation or flashover conduction and cause the glass to shatter. Be aware of this possibility. This author is not aware of documented examples of this, but includes it as a possibility and recommends facing the interior of the car or building during shelter from an intense electrical storm."

Here is some documentation to consider. :)

http://www.freerepublic.com/focus/f-news/1397994/posts
N4FOZ 2008-07-24
Lightning Safety
That, folks, is what I call an excellent article!
KC0RBX 2008-07-24
Lightning Safety
I'm not an professional at the National Weather Service, I only play one on Ham Radio. Having said that, I know I know, that was a joke, c'mon, I am a NWS certified weather spotter. Some of the posts about this article have implied that they NEED to stay "connected" so they may be "informed" for "necessary" reasons because of their "official" duties. B.S. The weather service does not require you to be a hero by riding out the storm so you can provide them with "precious" second by second information. If you are watching the storm online or some other way and can tell it is coming right at you, then you KNOW it is time to take the stated precautions. The whole point of the weather service is to prevent death. The weather service employees don't want to hear about a hero who died giving them info. They don't need it THAT bad. So disconnect your stuff and take cover.
W5HTW 2008-07-23
RE: Lightning Safety
Two weeks ago my son in Port St. Lucie, FL had just arrived home. Walking from his car to the house, he was nearly a victim of those "runners" mentioned earlier. There is a ham across the street from him, and lightning hit the tower. My son, in wet grass in his yard, was stunned, but not seriously injured. He said he couldn't think clearly for a couple of hours, and his arms, especially his elbows, ached and were very stiff.

New Mexico claims to be the state with the 2nd highest incidence of dangerous lightning, only behind Florida. Most of ours is also in the monsoon (which is in effect now) between the first week of July into the first week of September. We have few deaths in New Mexico, as far as I can tell.

But we do have damage. My property has been struck several times, resulting in moderate damage, but never to my radios. It fried my garage door opener, wiped out my electric water heater, blew up two telephones, destroyed a heavy duty UPS but did not affect the computer, burned out the motor in my swamp cooler, opened the neutral-ground connection in my home, putting 120 VAC on all metal around the house, cooked two answering machines, and blew out my mercury vapor yard light. Not all at once, but in multiple attacks.

For some reason my radios and antennas have survived, one of the antennas for 15 years!!

Just a few days ago I was sitting at my desk (my tv, computer, UPS, radios and answering machine were all unplugged) and that was that little 'crunch/crackle' that tells you the strike was close enough to burn your whiskers. Following instantly, of course, by the artillery shot. Nothing like it. That "snap" or whatever you want to call it, a split second before the sharp thunder crack, is really, really frightening. You know something has been hit, and with my record of property damage over the years, I immediately went through the house, and looked out every window. As far as I can tell, it was what is known as an 'air strike' but it had to be within a few yards of my house. Sounded like it was on the roof, but rain since then tells me my roof wasn't damaged.

I've seen terrifying lightning storms in Virginia, and in Delaware. In Virginia one wiped out my dipole, just vaporized it, my tv and my stereo. In Delaware, I worked at a radio station with a four tower array. What a sight! Lightning played with those towers, sometimes all four of them at once, in the most dazzling display way behond my imagination. But the station rarely suffered any damage.

Ed
W7ETA 2008-07-23
RE: Lightning Safety
"...three species of reptiles."

Lets see, Divorce, Criminal Defense, and Class Action?
73
Bob
KF4HR 2008-07-23
RE: Lightning Safety
"Most here have too much time on their hands, worrying about lightning. Myself, I will just buy new stuff with my insurance money."

Obviously you have never had to go through the hassle of dealing with an insurance company over equipment that was damaged by lightning.

First, before heading out to buy that "new stuff" I'd recommend checking to make sure your equipment is even covered. Some or all of it may not be.

Also don't think for a minute insurance companies will automatically take your word for it that your equipment was damaged by lightning. It took me months to have all my damaged equipment inspected and the appropriate paperwork drawn up by authorized repair facilities before my insurance company would pay off. The experience was not fun.

Believe me, lightning damage is worth worrying about. And also keep in mind a direct strike could damage a lot more than just your "stuff" (equipment).

KF4HR
K5END 2008-07-23
RE: Lightning Safety
I should clarify Wyoming has the highest per capita, while Florida has the highest actual number of lightning fatalities.

The number 32,400/year is low, considering Alaska has over 570,000 square miles.

That is one strike per year per 20 square miles.

Alaska has so many fires simply because of the vast boreal land mass multiplied by the relatively low rate of lightning.

I see you're from Anchorage. I'm from Bethel, "originally."

K5END 2008-07-23
RE: Lightning Safety
Yes, you just had Alaska Lightning Safety Week in June as declared by Governor Palin.

Alaska has the fewest PER CAPITA lightning fatalities of all the 50 United States. Wyoming has the highest.

Alaska had zero lightning fatalities between 1990 and 2003.

Lightning starts 95% of the wildfires in Alaska.

Alaska's climate does not tend to generate thunderstorms. Most of Alaska's lightning occurs between May and August, mostly when cold outbreaks occur over the Summertime land and waters.

Alaska also has no indigenous snakes, sales tax or state income tax, and only three species of reptiles.






KL7FH 2008-07-23
Lightning Safety
Lightning is NOT rare in Alaska....Each year, there are an average of over. 32400 lightning strikes in Alaska.
That's why we have so many forest fires.

http://ams.confex.com/ams/pdfpapers/85059.pdf

73 Frank
N8NSN 2008-07-23
INSURANCE ? NEVER, NEVER ASSUME ! ! !
KD4LLA Writes :

"Most here have too much time on their hands, worrying about lightning. Myself, I will just buy new stuff with my insurance money."

I feel, perhaps, the above statement may have been made with the assumption that all new, as well as seasoned, amateur OPS have made the efforts of researching insurance law and NEC requirements concerning residential amateur radio installations. There are many people who would assume such a "pay-off" would take place simply because they are paid current on the homeowners insurance policy they carry. After a little research I have found some information that a lot of amateurs would find helpful.

1) An amateur radio station, in almost ALL cases of underwriter / insurance claims investigations, requires a "rider policy" to be in place on the electronics equipment in order to be covered by a home owners insurance policy.

2) Once this "rider policy" is in place you have opened yourself up to a whole new set of laws and requirements for the "amateur station" to meet "payment liability" of the insurance policy provider. With said rider policy the station MUST meet or exceed ALL NEC (National Electric Code) grounding requirements in order for the investigation process to find the "event" to be a candidate for insurance pay out. If there is no policy on the station, Heaven forbid the station should take a strike, the house burn to the ground or even worse personal loss is suffered, the insurance company, as well as the court system, may indeed determine that there is NO LIABILITY for the insurance company to pay on ANYTHING !

*) For information on NEC grounding requirements; Information is available on line (google search "National Electric Code")or a copy of the NEC can be readily acquired at most good book stores. Honestly, before you "assume" anything concerning your coverage SPEAK TO YOUR INSURANCE AGENT BEFORE HAND ! That is what your agent is paid for... To research the laws and policy requirements of YOUR situation and offer you the coverage needed to protect your assets. Never (and I mean NEVER) preclude that you are covered without knowing for sure. You may be surprised in what you hear from your agent.

*) The insurance companies, over the years and in this new age of residential electronics, have done their homework, per SE, to "KNOW THEIR OPTIONS"... Have You? In "KNOWING THEIR OPTIONS" I am simply using the logic that the insurance companies have done extensive (very extensive) research into the law, to know where the "loop holes" are, in order to keep payouts to a minimum. That is simply common sense. The insurance companies are not in business to give away money.

*) I am certainly sure that a lot of folks are under the impression that their insurance company would never treat them so poorly. However, think about the many situations we hear of these days when the insurance companies found so many ways not to pay... Katrina comes to mind... I am sure there are a myriad of other events you too can recall.

*) Certainly not trying to "take a poke" at anyone. Simply using a little logic and some research on insurance policy law to offer a more reasonable thinking process to the ever so common statement of...

"I will just buy new stuff with my insurance money."
AB7E 2008-07-23
Lightning Safety

I'm not even sure it would take a true lightning strike to kill someone. About a year ago (during the southern Arizona "monsoon" season) I had installed a temporary Inverted-V on a 55' pole at my QTH. I hadn't shunted it for DC since I didn't plan to leave it up very long, so I always tried to leave the end of the coax in the shack disconnected, shorted, and lying on the floor to avoid zapping the rig with static buildup from the antenna. One day a storm began to develop and I noticed that the end of the coax, although disconnected, was not shorted. That situation usually results in half-inch sparks jumping every couple of seconds from the center pin of the PL-259 to the shell, but in this case that hadn't started to happen yet so I reached down to attach the short before the storm got closer. I had one hand on the concrete floor, and as I reached for the cable (not the connector) with the other hand, a heavy blue arc at least two inches long jumped to my hand from the PL-259 and zapped the biceps muscles in both arms so hard that they were sore for three days. There had been no local lightning strike yet, no induced impulse, etc, and my hand never even got close to the connector. This was simply the result of my antenna picking up a heavy charge from the clouds and me creating a discharge path for it to ground ... kind of a mini lightning strike of its own, I guess. It was rather sobering to do a web search to find out how much voltage it takes to jump two inches of dry air, and the thick blue arc and my sore biceps attest to some fairly heavy current as well. I'm in good cardiac health, but I'm not sure anyone who wasn't would have been as lucky.

73,
Dave AB7E
W4VR 2008-07-23
Lightning Safety
For a video of natural ball lightning go to: http://www.youtube.com/watch?v=6ioN-3UWYrY&feature=PlayList&p=A5B4897404F34F8B&index=0
AB7E 2008-07-23
RE: Lightning Safety
KD4LLA: "Most here have too much time on their hands, worrying about lightning. Myself, I will just buy new stuff with my insurance money."


That is the qualifying mentality of a Darwin Award ...

Dave AB7E
KC8DE 2008-07-23
RE: Lightning Safety
I haven't found an insurance policy yet that can replace a terminated life. If you find one, let me know where I can sign up!

Doug
K5END 2008-07-23
RE: Lightning Safety
"KD4LLA on July 22, 2008
Most here have too much time on their hands, worrying about lightning. Myself, I will just buy new stuff with my insurance money. Mike"

Levity, I hope. :-)




AI2IA 2008-07-23
Lightning Safety
KD4LLA - please don't miss the very important point. Most of us don't worry about lightning, but we like to be reminded from time to time to respect it, and to do everything we reasonably can to avoid its harm to people and to keep our equipment well grounded and safe.

Reminders from time to time are good things. Hopefully, during a severe lightning storm you will recall the safety tips given here to keep you and others safe from danger. We can avoid lightning harm to ourselves, but only if we try.
AB2WK 2008-07-23
RE: Lightning Safety
While watching the daily afternoon thunderstorm in Houston a few years ago, I was sitting in front of a window. Outside the window to the left was a cable tv box about 5 feet away. Out of nowhere I felt like I had thousands of ants crawling all over me and it sounded like the world exploded. I ended up on the floor about 10 feet behind the window. Afterward I realized lightning hit the cable box. There were only a couple of pieces of metal hanging where the box had been. If I had the window open I would have probably been killed. Since then you won't find me close to a window during a storm!
K5END 2008-07-23
RE: Lightning Safety
"the myth alive that "nothing can be done" to prevent lightning damage to equipment. "

You are correct.

There is a lot you can and should do to protect your equipment and assets, the most important of which is the part that breathes.







NV2A 2008-07-23
RE: Lightning Safety
"A sharp thunder report implies the site of the ground strike is nearby, nothing more."

Amen to that! While parked in front of a restaurant sign post during a violent rain storm, a lightening bolt hit the sign just as my friend and I had decided to exit the vehicle. His right leg hit the ground, shot back in the car and he slammed the door and his pant leg was dry despite the driving rain storm! He was quick.

The sound was exactly like having your head inside a fresh apple when someone chomped it open. The closer you are to the activity, the less muffled and sharper the sound.

If there were any exaggerations in the article I don't mind them, after all, it's hard to exaggerate the power of a lightening strike.

PS, we went without the coffee and waited out the storm in the car.
K9KJM 2008-07-22
RE: Lightning Safety
Very good article about personal lightning safety.
Thanks!

Too bad however that some misinformed posters still try to keep the myth alive that "nothing can be done" to prevent lightning damage to equipment.

Cellphone tower sites, Commercial radio and TV stations, Public safety communications repeater systems etc etc. do not have the option to "disconnect" anything at the first rumble of thunder.
Tall tower sites on hilltops that take direct lightning strikes most every large storm and have properly bonded and grounded systems do not suffer any damage from the direct strikes.

Although it is a fair sized project to properly protect a ham station, It CAN be done for a reasonable amount of money if common sense is used instead of simply throwing money at new supplies. Old used copper works every bit as good as shiny new copper, Scrap yards sometimes sell wire and flat copper flashing for much less than retail stores, Heavy copperclad ground rods can be purchased from some power companies
(Used-) As they are mostly steel have very little salvage value. They are easy to straighten out and reuse) etc etc.

For some good information on station protection:

http://members.cox.net/pc-usa/station/ground0.htm

KB1NXL 2008-07-22
Lightning Safety
As an electrical engineer by vocation and an amateur radio operator, i understand the principle of the skin effect and the concept of a Faraday cage. What i didn't know and could not forsee was being an actual survivor of a lightning strike while driving my car. During a recent thunderstorm in my area, which is the northeast, but this summer feels more Floridian with the almost daily thunderstorms, i was driving home from (what else on a Sunday...) a hamfest when a lightning bolt struck my car while driving on the highway. Bolt destroyed my two antennas on the roof of the car, the radio connected to the antenna, the car, and the left front tire - all lightning will find its ground, in any path it chooses. As physical evidence of the bolt, a singed black hole resides on the spot where my antenna once occupied. The bolt also went through the cable, but did not hit me as most of the energy, as we are tought, flowed around me in the faraday cage made up of the metal skin of the car. the damage was severe though, as my car's multiple computers were instantly fried and the rear window was blown out either by the electical jolt (as it contained the mesh of ribbon cable known as the defroster) or the massive KABOOM pressure wave as i've never heard as loud a sound and i've witnessed many t-storms. Needless to say all my friends and relatives are relieved and glad i'm ok. but i am now in the process of purchasing a new (or used...) car, definitely all metal. I consider myself a survivor and beginning my second life, but who knows how many i have left?

It is true that the safest place in a t-storm other than inside your home, away from anything metal, is in fact your car. I'm proof!!

Rick KB1NXL
K6JPA 2008-07-22
RE: Lightning Safety
I'm a Fire Captain by profession. Approximately 15 years ago, I responded to an incident involving a vehicle that ran off a freeway and into a shallow pond. The pond happened to have high voltage transmission line towers anchored in it, and there was a a lightning storm in process during the incident.

I was standing at the edge of the pond when a lightning strike hit one of the towers, and apparently indirectly found a path through me. Although I don't remember the event happening, I've been told that I threw a flash of light from my arm to our rig over a distance of several feet as I was thrown through the air. Fortunately, the rest of my crew was not hurt.

My first realization of what had happened involved looking up to see my crew staring at me with medical bags open everywhere, and feeling like I had been hit by a truck.

I fully recovered from the incident, but have gained a great appreciation for lightning as a result. One big lesson learned is that the energy from a lightning strike can impact you even if you aren't directly in it's path to ground.
KC8DE 2008-07-22
RE: Lightning Safety
Isn't it a misnomer to say a ground system is there to dissipate lightning energy? Isn't it more accurate to say a well designed ground system exists to ensure all points of interest rise and fall at the same potential during an electrical event? There will be a step potential across the ground and/or system no matter what you do, but the more earth ground points on a given conductor, the less step potential (load) that conductor has to carry, correct?

Better to keep your home's electrical system at the same potential as your station ground (and all other pieces of equipment such as the antenna/feed, telco, CATV, etc.), lest you suffer your kilobuck rig becoming a bridge between the two.


Doug

AD5TD 2008-07-22
RE: Who is really IN CHARGE ?
http://www.flickr.com/photos/i_love_the_slow_loris/2646424593/
KD4LLA 2008-07-22
Lightning Safety
Most here have too much time on their hands, worrying about lightning. Myself, I will just buy new stuff with my insurance money.

Mike
WA4DOU 2008-07-22
RE: Lightning Safety
" When they say "you have a better chance of winning power ball than you do getting hit by lightning." Pure ignorance. "

From what I've read on the subject, you have one chance of being struck by lightning in 3500 years, statistically speaking, as an ordinary person. (Probably higher as a ham). Winning a powerball lottery equates to about the same statistical odds as getting hit by lightning 14 times in one day.
AI2IA 2008-07-22
Lightning Safety
I am sixty-five now, and this is about what happened to my parents about twenty years ago.
They were in their Florida room with the windows open during a typical Florida downpour. They were sitting on opposite ends of a long couch watching television. A lightning bolt came in one of the screen windows between my mother and my father, struck the TV set, burned out the outlet behind the set, made a sharp left turn into the kitchen and went up the stainless steel stove hood exaust vent outside the house and scorched the neighbors siding. The window, the television and the stove hood and vent pipe in the kitchen were destroyed. The wall behind the TV set was scorched. The outlet was burned and melted. Fortunately there was no fire, only a stench, and both my elderly parents lived to tell about it. - Ray, AI2IA
KE4ZHN 2008-07-22
Lightning Safety
Nice article. This reminds me of that old TV commercial "Its not nice to fool mother nature" Boom!
KN4LF 2008-07-22
Lightning Safety
Excellent article. Check out my website "My Very Close Encounters With Florida Lightning Bolts" at http://www.kn4lf.com/kn4lf1.htm .

73,
Thomas F. Giella, KN4LF
Lakeland, FL USA
W0FM 2008-07-22
RE: I don't get it.
When I was a teenager, I was sitting in my bedroom flipping through Hot Rod magazines. It was a summer afternoon and rain had begun to to fall, and there was an occasional rumble of thunder. We didn't have AC in that part of the house, so my bedroom window was wide open. We had a canvas awning above my window, so even during some pretty hefty rain and thunderstoms, my window stayed open.

Before long I heard a huge explosion and saw a bright flash at the base of our ash tree outside my window. Just as instantly, a bright white ball came through the window, across my bedroom and blew the clock radio sitting on my dresser to bits.

Having experienced that, I found your article "electrifying". Thanks for taking the time to put the facts out there for us.

73,


Terry, WØFM
K0BG 2008-07-22
RE: I don't get it.
I should have added one comment to what I said before with respect to horizontal lightning. It happens a lot in New York, and other places with high-rise buildings. Just ask any good phone man how they protect themselves from that!

Alan, KØBG
www.k0bg.com
K5END 2008-07-22
RE: I don't get it.
"This church steeple is not only the highest object in the village, but it sits atop the highest hill in the area. This steeple has been zapped by lightning several times over the past 150 years"

One of those virtual science channels or almost-history channels had something about this.

Seems in older days townfolk would gather in the church to pray for safety from the storm. But it was usually the tallest structure in the area.

Many got to go to their reward (or otherwise) sooner than anticipated. I guess there are worse places to die than inside a church, praying...sort of the spiritual anti-thesis of death by jealous husband. :-)
K5END 2008-07-22
RE: I don't get it.
"read about something called "lightning runners" which can form when lightning strikes the earth and some of the undissipated energy forms a "runner" that travels above the ground until it strikes something."

Sounds like flashover (as in flashover not related to skin effect.)

There is a ground voltage gradient associated with a lightning event, and it may exceed the breakdown voltage of air.

Would be an interesting thing to research.
K5END 2008-07-22
RE: I don't get it.
"Grounding systems are not designed to prevent your antenna from being hit by lightning. They are designed to disipate as much of the energy as possible if it is hit, directing current away from the house and equipment."


Hear, Hear. Well said.

This article avoided equipment and structure grounding by intent, and was meant to discuss personal safety. Note that this and the article on power line safety were written to address human behavior and how our actions can lead to injury, and less about proper grounding or wiring techniques. One exception is the caveat (in the other article) about antenna installation as implied in the context of actually raising the antenna.

There is much reading available already for grounding and protection practices that it would only be iteration after reiteration.

But compared to the amount of material on safety, one would think that it is taken for granted that people realize the dangers.

The tragedy is that it IS taken for granted.


KF4HR 2008-07-22
RE: I don't get it.
"Ball lightning is an enigma, and even disputed,..."

I feel fortunate I saw ball lightning once (luckily from a safe distance). I'm certainly no expert in the matter but my thought is, even the best ground system has some resistance involved. Taking into consideration the super high voltage and current involved with a lightning strike, if you do the math even a few ohms of resistance develops one heck of a lot of energy that doesn't get instantly dissipated to ground. Perhaps that has something to do with the development of ball lightning.

Along those same lines, I've also read about something called "lightning runners" which can form when lightning strikes the earth and some of the undissipated energy forms a "runner" that travels above the ground until it strikes something.

KF4HR
WA8MEA 2008-07-22
RE: I don't get it.
I always enjoyed the story told by Jim, K8IMR. Jim was a "snow bird". He traveled from Michigan to Florida in the winter.

During a winter season t-storm, Jim had all of his shack antennas disconnected. (Standard procedure for him.)

He SWEARS that a "fire ball" came out of one of the coaxial leads and hovered around the room for at least a half a minute....until it disappeared.

I've heard of "St. Elmo's Fire"....but not traveling down the coax and popping out into the shack!

BTW, we are awaiting the ashes of the organist at our little village church to be blown all over town one day. Her ashes are inside an urn located atop the church steeple. This church steeple is not only the highest object in the village, but it sits atop the highest hill in the area. This steeple has been zapped by lightning several times over the past 150 years.

73, Bill - WA8MEA
http://HamRadioFun.com
tinytenna@hotmail.com
K5END 2008-07-22
RE: I don't get it.
Thanks, Steve

I was hoping you'd get a charge out of it. :-)
AA4PB 2008-07-22
RE: I don't get it.
Look at it this way: If you play golf in a lightning storm twice then your odds of being struck are double that of only doing it once :-)

Grounding systems are not designed to prevent your antenna from being hit by lightning. They are designed to disipate as much of the energy as possible if it is hit, directing current away from the house and equipment.
WB2WIK 2008-07-22
RE: I don't get it.
Nice article!

I found it positively shocking.

:-)
K5END 2008-07-22
RE: I don't get it.
quote, "When they say 'you have a better chance of winning power ball than you do getting hit by lightning.' Pure ignorance."

For some, lightning injury or death is infinitely more likely than winning the lottery.

Powerball is a tax on math ignorance, therefore not everyone plays.

Lightning makes no such discrimination.

That doesn't mean if you play the lottery enough you won't get struck. :-)
K3NRX 2008-07-22
RE: I don't get it.
One way to ensure zero lightning in your life is to move to areas where lightning is very rare. Alaska is said to be essentially lightning free.

REPLY: As I am as far north as I EVER want to be, that is NOT an option. However, I greatly appreciate this information. It is a sad testimony to society when I frequently encounter people who poo poo the dangers of lightning. When they say "you have a better chance of winning power ball than you do getting hit by lightning." Pure ignorance. After being a ham for 23 years and being very lucky in avoiding lightning strikes, I need to ask if anyone knows of any links that our out there giving advise on lightning protection, not just for ham gear and antennas, but for everything? Maybe someone should do an article on that very topic! Thanks for the great write up. I found it very useful.

Vince P
KA3NRX

K5END 2008-07-22
RE: I don't get it.
Ball lightning is an enigma, and even disputed, however Alan is a credible witness and source.

I think it may be associated with the step leader phenomena that define the path of a stroke. That would explain why it moves through space.

According to what I have read, the lightning stroke path does not form all at once, but regions begin to ionize somewhat like links in a chain called step leaders. It seems to me that the step leaders then, can and do exist autonomously and that the decaying effects near the end of a lightning event could generate individual step leaders that occur separately yet sequentially along a path, giving the illusion that they are moving, exactly the same illusion caused by the frames of a motion picture. But that is not a rigorous theory I am proposing.

I've observed Zodiacal light and a lot of other rare stuff, or even stuff I could not explain away, but not ball lightning.

I won't wish for an opportunity to witness ball lightning. Sometimes wishes come true! I'll pass on that one.
K5END 2008-07-22
RE: I don't get it.
quote"'1. Lightning is an everyday killer across most of the United States.'
I think this statement is a little misleading."

It could have been worded better, no doubt. The local colloquialism and connotation have seeped through my journalistic filters. :-)

By "everyday" I mean it is a quite natural hazard that people overlook and underestimate.

By "across most of the United States," I mean that in most regions of our country there is lightning risk, and that I don't have data on lightning-related fatalities outside the U.S.

One way to ensure zero lightning in your life is to move to areas where lightning is very rare. Alaska is said to be essentially lightning free.
KF4HR 2008-07-22
RE: Lightning Safety
"Would connecting the coax to another length of coax leading outside to a ground do any good? I noticed one of the posters disconnects his coax outside the house. Is that a better idea than just disconnecting the rig inside."

Don - Consider this. The level of damage a lightning strike can produce will depend on whether you receive a direct strike, or induced energy from a nearby strike. In the case of a direct strike, (in my opinion), all bets are off. You may have seen the after-math of a lightning strike splitting trees in half, or catching houses on fire.

Based on my experiences I keep all amateur electrical conductors (coax, heliax, control & power cables, etc) disconnected and grounded "outside" the house, and also make sure all grounding precautions are taken at the base of the tower as well. The idea being, try and dissipate as much of the lightning energy outside. Keep in mind that lightning is looking for a way to neutralize itself. Once inside your house it will attempt to jump to any ground, or near ground potential. Typically this means your house wiring (electrical, cable, phone lines, metal water pipes that may be grounded, etc). I think it makes good sense to take steps to keep that potential energy outside your home. I have all my amateur cabling routed through a feed-through panel on the back of my house. This is my main disconnect point.

And you are right, disconnecting everything has the disadvantage of not having to the ability to monitor worsening weather conditions. As one poster noted, a wireless laptop (on batteries) and sacrificial wireless LAN , along with a HT, could provide the information required.

I'm a retired FAA Weather Radar Program Manager. As I'm sure you're aware weather radar systems must remain operational 24/7. In order to accomplish this, there are extraordinary grounding efforts that take place; (at NEXRAD radar facilities for example). The costs involved with these grounding efforts are financially staggering; well beyond the financial means of most amateurs.

KF4HR
KB1OOO 2008-07-22
RE: I don't get it.
Thanks for the nice article K5END. Just a comment:

"1. Lightning is an everyday killer across most of the United States."

I think this statement is a little misleading. At first glance, I'd interpret it to mean that someone in the US gets killed by lightning every day. People don't die everyday from lightening strikes, there have been 20 deaths recorded by the national weather service so far this year. Do you mean that lightning has the potential to kill across most of the US everyday? Even then, thunderstorms don't occur across most of the US everyday.
K5END 2008-07-22
RE: I don't get it.
"I don't understand this at all.
Where did 0.0000033 come from, and what does it mean?"


"They" tell us that 100 milliamperes can be lethal to humans.

0.100/30,000 = 0.00000033, approximately.

The figure is a general statement to indicate the current magnitude in lightning compared to the magnitude of current regarded as lethal to humans.

Think of it as wetting a postage stamp (the old kind) with a fire hose. :-)
AI2IA 2008-07-22
I don't get it.
"Cloud-to-ground voltages range from 100 million to 1 billion Volts.
Typical peak current is 30,000 Amperes. This means that only 0.0000033 of the electrical current in a routine lightning strike is lethal."

I don't understand this at all.
Where did 0.0000033 come from, and what does it mean?

Can anyone explain it?
K5LXP 2008-07-22
RE: Lightning Safety
W6ZPC wrote:

> Any suggestions on how to protect devices that must
> be left on during storms?

For the internet NWS feed, use a wireless hub and a laptop with wireless running batteries. Consider the hub expendable.

Mark K5LXP
Albuquerque, NM


NA4IT 2008-07-22
RE: Lightning Safety
W6ZPC:

1. Use only enough antenna to get your signal out (i.e. as low as possible), be sure it is a DC grounded antenna, ground the coax where it comes in and use a lightning arrestor. Keep that radio separate from the rest of your shack electrically.
2. Use a very good surge arrestor on your modem and computer.
3. Have a B I G savings account.

I am a Skywarn net control. I have probably been through 10 modems in 5 years. One modem got destroyed by a lightning strike that hit a telephone pole (and split it from top to bottom) that was a mile away! Just part of life.

de NA4IT
K0BG 2008-07-22
RE: Lightning Safety
There are two rare types of lightning most people never see. They are horizontal and ball. Oddly enough, you typically see them together. One such place is outside Salt Lake City. The radio and TV stations are located on a mesa between two peaks. Thus the strikes to go between the two peaks and right across the transmission site.

Ball lightning is a form of St. Elmo's fire, and if you get hit by one, it can kill. The three or so balls I have seen were about 3 feet in diameter, and INSIDE of one of the transmitter buildings.

When the lightning starts at the site, you don't leave! Until, that is, it's over. So, even indoors can be a problem in some cases!

Alan, KØBG
www.k0bg.com
AA4PB 2008-07-22
RE: Lightning Safety
Years ago I was sitting in an electronics class at the Naval Air Station, Memphis, TN. The window in the class room was open. There was a lightning strike and that white ball of light, about basketball size, came through the open window and passed between the instructor and the class. I saw it go through the door and down the hall where it discharged into an electrical outlet leaving the wall charred all around it. It was a good thing that nobody was sitting in its path.
W6ZPC 2008-07-22
Lightning Safety
I an a fairly new ham, but have been a weather watcher and radio news reporter for many years. I have also done storm spotting for the radio station, reporting conditions from a hilltop with microphone in hand (I guess I was very lucky). I agree with everything in the original article and subsequent postings. My problem is, I use my computer to monitor the National Weather Service radar to track storms and possible tornadoes during storms. Were I to unplug everything, I would have no warning of an approaching tornado. Yes I do have an NOAA radio for alerts, but watching the storm on radar gives me added information which I can also relay to our Skywarn groups which are storm spotting. I am sure the NWS doesn't unplug their computers during thunderstorms. Any suggestions on how to protect devices that must be left on during storms? I have considered installing WIFI in the house and using a battery power laptop to monitor the radar, but is that the most cost effective way of dealing with the threat. I do disconnect my HF and VHF gear from the AC mains and the antennas when I am not using them, but I have wondered, as was posted earlier, if lightning striking my antenna could not jump the few feet from the end of the coax to something else in the room. Would connecting the coax to another length of coax leading outside to a ground do any good? I noticed one of the posters disconnects his coax outside the house. Is that a better idea than just disconnecting the rig inside. I have had outside antennas for years and the only losses I have suffered were the low noise amplifiers commonly installed in TV feedlines.
K5END 2008-07-22
RE: Lightning Safety
Thanks, Butch.

See this month's QST. It discusses ground rings installed to prevent or mitigate the kind of damage you described.

The protection mechanism is similar to that in a closed car or a Faraday cage. Gauss' law states the voltage in a conservative field around a closed path is zero. Copper does not provide a true, superconducting, conservative path. There is some loss. But it beats dirt conductivity by far.
KF4HR 2008-07-22
Lightning Safety
Back in the mid-80's I experienced a lightning strike that struck the ground in between my house and my neighbors house. (Our houses are separated by about 250 feet.) I just happened to be looking outside when the lightning bolt struck. I was amazed the bolt of lightning didn't hit other nearby objects which were higher; houses, trees, my tower, etc. A fraction of a second after the initial flash I saw what I think may have been ball-lightning. A white circular ball of energy (about the size of a basket ball) was hovering about 2 feet in mid-air, right over the point where the lightning strike hit. The energy ball hung in the air for about a second, then disappeared with a loud "POP" and some sizzling sparks. Pretty strange!

Unfortunately this strike occurred right where our underground power, cable TV, and telephone lines leads to our house. The energy induced into those underground cables was enough to take out everything electrical in our house; TV's, VCR's, ham gear, stereo amplifier and components (even some of the stereo speakers had their voice coils burnt open), garage door opener fried, clocks dead, light bulbs, phones didn't work, etc, etc. Over $10,000 damage occurred in a split second. When the lightning struck my wife was watching a small TV in our kitchen and said she saw a large spark jump out of the back of the TV set (before it died). Instantly our house was totally quiet and dark. I found that several of my house circuit breakers had been tripped, but not before the damage was done.

Over the next few days I began to find more lightning damage. For example the rotary switch on our washing machine had internally melted.

By hitting the ground I assume a partial amount of energy from this lightning bolt had been absorbed into the earth but there was still more than enough energy induced into our underground cabling to cause plenty of damage.

Our insurance company eventually paid to replace the damaged items, although they insisted I have each item checked by a repair shop and a document drawn up indicating that the damage was indeed done by a lightning strike. This took us several months to accomplish.

Sometimes I have to laugh when I hear people say that their ham gear is protected because they have it well grounded and their antenna switch has been switched to the center (grounded) position. Considering a lightning bolt can jump miles through the sky, do these people actually think lightning is going to have a difficult time jumping across a RF switch? :^)

Lessons learned:

* Definitely take shelter in an electrical storm and remember lightning is unpredictable!

* For you that have outside antennas, you have stacked the odds against yourself, so do whatever you can to minimize the damage from a strike:

1. You can never have enough ground rods and thick cabling at the base of your tower. The more the better. The more energy you can dissipate into the ground, the less there is to jump somewhere else.

2. At the first sign of an approaching storm, all my amateur cabling gets disconnected "outside my house" and each cable is grounded.

3. Everything gets unplugged from the AC power source, to include phone and cable TV connections.

4. If possible, lower the tower(s).

5. When pondering where your tower installation consider installing it away from your house.

Bottom line. NEVER under estimate what damage lightning can do.

KF4HR
N8NSN 2008-07-22
Who is really IN CHARGE ?
Thanks Mr. Kendall. I have been looking forward to this article. As it reads... A little prevention goes a LONG way.

Funny story about lightning:

Back when my ex-wife was in her mid teens there was a normal (if we can call it such) thunderstorm here in the Dayton area on the day referring to this post. Jane was staying inside on that day because of the rain. As she sat in her room reading a magazine (Tiger Beat teen magazine) she felt what she described as a "tingly" sensation in the air of her room. Her room was on the second floor and had two windows in it. There was a window on the south wall as well as one on the west wall. On the west wall, of the exterior of the home, there was a telephone line that ran down the outside of the structure, from a feed in the basement, to her fathers room which was adjacent to her room. As she sat and read the storm was passing through the area. Not even being a "strong" storm she relaxed there reading with the windows open. I am sure many, as well as myself, do similar things as a subtle summer storm passes through; Relax indoors with the windows still opened. Just seconds into the "tingly" feeling Jane heard an amazingly loud crackle sound and a very large flashing was witnessed simultaneously with a deafening KA-BOOM ! ! ! All the lights went out and the strong smell of ozone lingered in the air ! It was evident that the lightning stroke came IN the room through the south window - passed through the "air" in the room - then exited the room via the west window and proceeded to all but vaporize the telephone line which traveled from the second floor to the basement ! True Story...

Even though we may seek shelter from a storm: I suppose there are still times even the most "planned out" safety zones can still fall short in the path of such an intense phenomenon. Lightning is indeed "in charge" (pun intended) during the short time that an actual stroke takes place.

Thanks again Mr. Kendall.