Lightning

[SPRINTERLIGHT]

I have two antennas on a 50 foot tower. One is a Solarcon vertical and the other is a end fed half wave long wire. Tower is grounded to a ground rod 10 ft in the ground
I am trying to protect my radio equipment from lightning strikes. I have been told the best solution is to disconnect the coax from the radio , unplug the radio from the wall receptacle and disconnect the ground from the radio. Now when lightning happens to strike in theory the charge will follow down the antenna ground into the ground rod in the earth and I should be relatively sure my equipment will survive.
My concern is the coax that comes from the tower into the shack. would not some of the lightning charge follow the coax into my shack. I have never heard it said that you also have to pull the coax from the shack , but I cannot feel sure that I have eliminated the problem without doing so.
I know there are a lot of you out there that feel I am going overboard but I do not want to take the chance and find out the hard way. Radio equipment is not cheap as you already know plus the safety of people in the general radio area are relying on me that they are protected.
I am hoping there is an easier way to protect my equipment and the safety of the occupants. Disconnecting everything in this procedure every time I think I hear a rumbling would be quite a choir. I look forward to hearing from knowledgeable ham operators on this subject .

 

[KC4RAF]

The part about disconnecting the cable from the radio is correct, as well as unplugging the power cord from the wall.
What some do, is to make a shorting connector that the cable connect to, thus shorting the antenna to ground. That way it is hoped that the lightning energy is grounded.
But one thing to remember is this: If the lightning bolt strikes VERY close to your equipment, even unplugged, the surrounding energy can still be strong enough to damage your radio.
Years ago I had unplugged every thing, but left the cable on my radio desk. Lightning struck the antenna, came down the cable and broke/split a mirror I had laying by the PL-259 connector. And it blew out about 5 speakers and my telephone. But none of my radio/transmitters were damaged!
So it is very wise to unplug ALL your equipment. And if you can, ground the cable coming inside your shack/home.
You are not going "...overboard..." with your concern. What makes you feel safe is very important.
hth you.
73

 

[KC4RAF]

My post about, "But one thing to remember is this: If the lightning bolt strikes VERY close to your equipment, even unplugged, the surrounding energy can still be strong enough to damage your radio.", generally won't happen. As in the case I wrote about my experience with lightning striking my antenna, it only blew out the speakers and telephone and broke the mirror.

 

[NM9X]

I have two antennas on a 50 foot tower. One is a Solarcon vertical and the other is a end fed half wave long wire. Tower is grounded to a ground rod 10 ft in the ground
I am trying to protect my radio equipment from lightning strikes. I have been told the best solution is to disconnect the coax from the radio , unplug the radio from the wall receptacle and disconnect the ground from the radio. Now when lightning happens to strike in theory the charge will follow down the antenna ground into the ground rod in the earth and I should be relatively sure my equipment will survive.
My concern is the coax that comes from the tower into the shack. would not some of the lightning charge follow the coax into my shack. I have never heard it said that you also have to pull the coax from the shack , but I cannot feel sure that I have eliminated the problem without doing so.
I know there are a lot of you out there that feel I am going overboard but I do not want to take the chance and find out the hard way. Radio equipment is not cheap as you already know plus the safety of people in the general radio area are relying on me that they are protected.
I am hoping there is an easier way to protect my equipment and the safety of the occupants. Disconnecting everything in this procedure every time I think I hear a rumbling would be quite a choir. I look forward to hearing from knowledgeable ham operators on this subject .

You can also install lightning arresters and surge protectors on your coax cables. I would still unplug if I knew a storm was approaching.
Here's some info Antenna Lightning and Surge Protectors - K3DAV.com - Amateur Radio Operator

 

[WA8ZTZ]

Not all lightning strikes are created equal. Some may just make a pinhole in a gutter or metal flashing and others can blow a brick chimney off of the roof of a house... or worse. It is also impossible to predict the path a strike will take through a building. What the lightning saw at the moment of the strike in terms of distributed resistance and reactance is beyond my comprehension. In my experience repairing damage in homes and buildings hit by lightning, it is amazing what path(s) the energy will take. Sometimes the damage is not immediately apparent... for example, stressed insulation in motor windings may not ultimately breakdown until months later.

So, what to do? Your best course of action is to follow the requirements of the National Electrical Code especially Articles 250 & 810. Study the manufacturer literature of surge protection products. There is all kinds of information on the internet; good, bad, and ugly. Stay away from ham radio anectdotal narratives and stick with solid engineering data from trusted sources. There are right ways to go about this and a whole lot of wrong ways.

To begin with, you will probably find that your single 10' ground rod is inadequate. However, the fact that you are concerned and asked this question shows that you are on the right path.

 

[NC1]

As a general rule, I connect the equipment before using it and disconnect everything when I'm done. This is especially true for the Spring, Summer, and Fall months when storms can come up out of nowhere without any warning at all.

A few times before I started doing this I had gone out for just a little while only to find out that 20 minutes after I left there was a thunderstorm that suddenly popped up. There was no way to get back in time to disconnect.

Thankfully everything was just fine, but now it is just part of my routine and I never have to worry.

 

[prcguy]

Its nearly impossible to protect an existing house and its electronic contents from a direct lightning strike, it would involve a complete upgrade of the electrical panel, wiring and massive buried grounding around the perimeter of the house. Adding a few ground rods and lightning protectors will not do much of anything and you would be very foolish to rely on such things.

There are commercial buildings like cell phone sites, mountain top repeater sites, satellite broadcast facilities, etc, that are designed from the ground up to withstand direct hits and they usually do. The last facility I worked at had over 75, 10ft ground rods bonded to 3/4" dia copper cable buried 4ft deep around the perimeter of the building and probably another 100 ground rods and buried cable around all the big satellite antennas and towers on site.

Then there was an impressive amount of copper buss bars under the raised floor of the building that bonded all equipment racks together and made home runs back to a central point at the buildings AC entry point. The goal is to make everything at the same ground potential because one of the things that destroys equipment plugged into AC power is having upwards of thousands of volts difference of potential on the ground wiring between equipment.

A Govt repeater site I occasionally work at has lost two of its fiberglass Stationmaster antennas over the last few years due to direct lightning hits and nothing inside the building was damaged because the mountain top site was built similar to what I described above to withstand direct hits.

I'm not trying to tell you how to make your home antenna lightning proof, I'm just pointing out its possible but not likely because of the high cost. The best advice I could give is ground to the National Electrical Code at the very minimum and disconnect your antennas and get the feedline away from anything you value when lightning is nearby. You can Google "nec article 810" to find lots of good info on how to ground antennas to meed code.

If someone gives you advise on doing this or that and you will be fine from a direct hit, ask them if they will pay for any damage if you get hit. Then see if they change their mind on the advise....
prcguy

 

[RFI-EMI-GUY]

Motorola R56 and Polyphaser white paper on bonding and grounding are a good place to start in researching lightning protection. If you install a single point grounding system which bonds to and expands the single ground rod that is below your electric meter and breaker panel you will have a good start. In my case I Installed additional ground rod at the meter because due to age, I have to assume the original has corroded substantially. Then every 16 feet around the perimeter of the house on two sides (in my case) I drove a new 8 foot red and bonded all of these together. Radio antennas, TV antennas, Cable and phone also bond to this system.

Sent from my SM-T350 using Tapatalk

 

[KC4RAF]

IF you had the money, you could go with a Faraday cage around your house...But that would be SUPPER expensive. So as others have pointed out, NEC is a good starting point as well as what RFI-EMI-GUY posted about the "white paper".

 

[rfradioconsult]

Check with your local electrical inspector as to what their rules are for antennas, then follow their rules. If you get hit at lest your insurance carrier wont have an excuse to not pay your claim.

 

[prcguy]

If an insurance company has any problems with paying a claim for lightning it will be spelled out in your policy, there is noting hidden there. My wife managed insurance claims for 20 something states and lightning is considered an act of nature or an act of God and is handled as the policy is written. My wife has never had a claim in question because of antennas or improper grounding of an antenna and they don't have people on staff who look for NEC infractions.
prcguy

Check with your local electrical inspector as to what their rules are for antennas, then follow their rules. If you get hit at lest your insurance carrier wont have an excuse to not pay your claim.

 

[SCPD]

Hi Sprinter...

I’ll add to the chorus of the good advice you’re receiving. This:
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http://lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf
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… is the gospel I go by for Lightning. I’ll limit that to just the term “lightning’ since its hubristic to think you can defeat Zesus by adding the word “Protection.” .
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That said, I work in settings that are constantly getting hit- even with the best (ie: most expensive) engineering; that the stuff can bugger its way into the most amazing places! … sometimes it seems to do nothing, other times its blast’d holes thru concrete block walls.
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. I’ll just amplify the other’s comments that it is highly unpredictable… But if you want another place to continue your research:

http://technav.ieee.org/tag/1046/lightning-protection
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….this subject gets very esoteric and involved… and as a consumer-level user, all this presents you with a daunting amount of information overload, not to mention expense. I am afraid that you will never be fully protected, so follow the expert’s and avoid -the like the plague,- the anecdotal advice, so freely given.
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But (conflict )... I like anecdotes… and here’s one:
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I have a home high in the Rockies- might as well call it Lightning Alley- where you get off the mountain peaks by 2PM and down below treeline fast.
“If you hear it, fear it--If you see, flee it”
A tad corny, but every year somebody will ignore it- to their detriment.
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Two summers ago while nearing the top of a 14’er, a sudden cloud bank moved in which silently cover’d the peak. In that thick mist everything metallic began to glow with the most beautiful green coronas-- it was St. Elmo’s Fire !
I have seen it before, on tops of towers, but nothing so up-and-close personal.. Bracelets, zippers, carabiners- My friend held out her hand and her rings scintillated silently.., it was as if we were observing the glow that comes from beneath the water barrier of a nuclear reactor….**
We marvel’d for but a moment and beat it off that ridge as fast as we could scramble. About 5 minutes later, Zesus unloaded on us with a bolt that hit the exact spot we’d been sitting.. and as the thunder rolled away, I could swear I heard him laughing.
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Ok, okay- I will make something out of all this.
Lightning likes sharp pointy things. That is where you will see coronas-- and why Telsa-like loaded antennas have big balls on their tips…etc.,the surface area displaces static charges.
Out in the West we have these big, funny looking stainless steel fuzz balls that the electric company puts up on towers about their transformer farms. We’ve tried the same, using children aluminum snow saucers on tower tops… The multitude of surface these objects present bleed off the static charges- or so the theory goes- before there is a chance to develop enuff charge for a lightning strike. They *seem* to work........................ Anecdotal, Anecdotal !!
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I think my friend and I were the glowing big fuzz ball on that ridge, moments before the strike.
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Anyway, for years I have had one of those stainless steel balls out on a 30 foot tower, on a ridge, right above my mountain home…. Nothing else on it, just a static ball on a ground’d Rohn tower… People ask what it is…. I call it “Art”
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But (I secretly know) its also my offering to Zesus … so far he’s just smiling at me.
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………………..CF
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**hey, we're physicists, what kind of analogy would you expect?....

 

[jonwienke]

The tl;dr version of good lightning protection and grounding could be summarized as follows:

Nothing normal folks can afford will provide complete protection against a direct hit by lightning. But good grounding practice can limit likely damage to the antenna, coax, and whatever devices are near them.

Your antenna tower/mast should have at least one dedicated 8-foot ground rod adjacent to the mast. The point where your coax enters the house should also have a ground rod connected to the shield of the coax. The wire between the rods and the item being grounded should be #6 or heavier.

All ground rods, including the rod(s) installed with the building electrical system, should be connected together with the shortest and straightest possible runs of #6 or heavier wire. Having redundant ground connections is not a bad thing--for example, if you have 3 total ground rods, having them connected in a more or less triangular loop can be beneficial, unless they are all in a roughly straight line.

Antennas with a DC connection between their active element(s) and ground are generally preferable, as they allow the dissipation of less-than-lightning static charges simply by grounding the coax shield. If your antenna does not have a DC connection between the active element(s) and ground, a surge protector on the coax will help prevent damage from less-than-lightning static buildup. But they will not help much in the event of a direct lightning strike.

Weather sealing electrical connections is always a good idea, especially ones outside exposed to moisture. But for some reason, this step is usually neglected when connecting wires to ground rods. Don't be afraid to march to the beat of a different drummer in this regard.

All of the above notwithstanding, it's good practice to unplug devices when lightning is active nearby and a direct hit is likely, both power and antenna connections. Good grounding is not a panacea against lightning, but can make the difference between only replacing antenna(s) and coax vs. having a lightning-induced house fire.

 

[jim202]

This is a common question that shows up very frequently on many chat groups.

There have been an untold number of threads on just this topic of how to protect "my equipment" and "my property". But just how many of those asking the question have even taken the time to do a search for related postings?

I myself have have contributed to a number of the treads on this subject and am actually getting tired of typing the same information over and over because people can't even be bothered to take the time to see if there might just be some postings on the topic.

My work does involve many years of building telecommunication sites and as such I do consider that my background provides the education of what to do and what not to do. If the person still doesn't feel their question isn't answered by taking the time to search the topic, then by all means come and ask the question.

 

[SCPD]

I, for one, hear you Jim. It does get quite exhausting, repeating the same messages, over and over. I taught graduate level for several years and found that it became an effortless exercise to repeat myself semester after semester-- so much so that I had to slap myself and get out- I was going halcyonic.
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But you know, I missed that, - that...., what is a good term?... "imparting of experience"... to to the inquisitive minds.. for after all, my experiences were hard won, and I don't want them to be for nothing- disappearing into the vacuum of time....
If some one can benefit, I'm happy to repeat, even if its only for a laugh.
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Still, Oh, do I hear you... my graduate students were supposedly a level above..... and I had to rethink my attitude... for you know, once any subject is broach'd, it starts a discussion that goes far deeper and longer than the original, often trite question-- for those of us that love teaching, that is the reward-- I can take that lead and run with it...
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..............................CF

 

[jim202]

One comment that just won't stop is that "you can't survive a direct hit from lightning".

This is so far from the truth. If it was true, you would see FM stations and TV stations never survive a storm. Plus the cellular carriers couldn't afford to keep their systems operating.

So boys stand up and show us all the true facts of all these towers killing their radio and TV stations from lightning strikes.

I have been building and inspecting telecommunication sites for many many years. The secret to surviving a direct lightning strike is how well you ground the entire system. Just grounding the tower isn't enough. Just grounding your equipment isn't enough. Adding surge protection is part of the system. A single ground rod will not be an effective ground.

Are any of you absorbing what I just said? A properly protected radio site will incorporate a complete system of protection. A low impedance ground is a must. A single ground rod is never enough. If you have sandy soil or rocky soil you will require some special efforts.

Enough said on the above. Yes I have been at a 500 foot tower when it took a direct hit. The tower legs were steaming in the rain from the heat generated by the high current of the strike. Going inside the equipment shelter revealed that everything was still functioning correctly as it should.

So stop saying that you can't survive a direct strike. IT IS JUST NOT TRUE. Those that want to keep spouting this false statement are just continuing this false impression. Your leading those new to the radio field down the wrong road. Why don't you try helping these people that ask for the right answers? I have been doing it for years. It's time for someone else to step up to the plate and help.

 

[SCPD]

Hey Jim, I agree with you completely.. the problem here is that these guys are radio hams-- their knowledge base is suspect- this is their hobby, not their occupations- To expect them to appreciate, let alone be able to apply, all the knowledge necessary to achieve that 95% perfection (I can not concede that extra 5 %-- you should see our latest fried 700meg trunked site- 'guaranteed' by XXX, a major telecom company... ) is not reasonable, not here .
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All these guys are asking for is some guidance, and they are going to receive a lot of bad information.
Personally, I feel if I am going to take the time to post anything here, it will be with good cheer, and though I may have said it a thousand time, each time my audience will be as if it was fresh and new...
or I'll go back to my other interests**
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But I'm with you, all the same

Smiles............
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.......................CF
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___________________________________
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**Polychrome pre-Colombian pottery

 

[RFI-EMI-GUY]

One comment that just won't stop is that "you can't survive a direct hit from lightning".

This is so far from the truth. If it was true, you would see FM stations and TV stations never survive a storm. Plus the cellular carriers couldn't afford to keep their systems operating.

So boys stand up and show us all the true facts of all these towers killing their radio and TV stations from lightning strikes.

I have been building and inspecting telecommunication sites for many many years. The secret to surviving a direct lightning strike is how well you ground the entire system. Just grounding the tower isn't enough. Just grounding your equipment isn't enough. Adding surge protection is part of the system. A single ground rod will not be an effective ground.

Are any of you absorbing what I just said? A properly protected radio site will incorporate a complete system of protection. A low impedance ground is a must. A single ground rod is never enough. If you have sandy soil or rocky soil you will require some special efforts.

Enough said on the above. Yes I have been at a 500 foot tower when it took a direct hit. The tower legs were steaming in the rain from the heat generated by the high current of the strike. Going inside the equipment shelter revealed that everything was still functioning correctly as it should.

So stop saying that you can't survive a direct strike. IT IS JUST NOT TRUE. Those that want to keep spouting this false statement are just continuing this false impression. Your leading those new to the radio field down the wrong road. Why don't you try helping these people that ask for the right answers? I have been doing it for years. It's time for someone else to step up to the plate and help.

I have been inside a commercial aircraft when it was struck by lightning. Other than the flash and bang and some cautionary words from the pilot, absolutely nothing went wrong. This is a perfect example of a single point grounding system (metal skin) that was raised significantly above ground potential.

If one strives to bond their equipment, antenna systems, utilities and tower structure to a well designed single point system they can achieve significant protection.

Sent from my SM-T350 using Tapatalk

 

[jonwienke]

So stop saying that you can't survive a direct strike. IT IS JUST NOT TRUE. Those that want to keep spouting this false statement are just continuing this false impression. Your leading those new to the radio field down the wrong road. Why don't you try helping these people that ask for the right answers? I have been doing it for years. It's time for someone else to step up to the plate and help.

Yes you can, but the equipment and the grade of wiring needed are out of the budget of most ordinary folks. An antenna and coax that is designed to handle 10KW continuously is more likely to survive a direct lightning strike than components designed to handle 100W. Commercial radio sites have more and heavier-duty ground rods connected by heavier-gauge wiring than you'll find at a residential installation.

Most people don't have the budget to build something that can survive a direct lightning strike with zero damage. It can be done, but will probably cost nearly as much as the rest of the house if built to the same standards as a 500-foot broadcast tower.

 

[SCPD]

I am going to take another tack to this subject. Its one thing for someone asking for help to receive a mountain full of advice… its quite another for them to put it all together into something they can use. You can only read so much or listen to so many ’lectures’ before you have to take it from there.
Having seen the Ham-Handed (pun intended) way that radio amateurs go about constructing their stations, its obvious many haven’t a clue about anything, especially when it comes to static suppression**
Sadly, their peers are often more liability than asset.
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I think one of the most valuable ways to learn is by example- seeing and doing along side knowledgeable people…. Which is exactly what I’ve been doing for the past couple of days- flying about the country looking at what my colleagues are up to-- (plus it also has given me a lot of time to post these oh-so profound ideas, sitting in planes and airports… )
There are somethings that no amount of Skype, Facetime, emails, photos or texts- can convey that seeing it first hand can replace.
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So to this end, I suggest that anyone serious about this subject arrange a Field Trip. A ham can gain a wealth of information by simply observing what the professionals have done…..Start by driving up to a couple of those ’cel sites, preferable ones also shared with 2-way services. Look about, see just what's there- how the cables are laid, the ground rods placed, the power lines draped…etc etc-- if you can find a tech to show you around; a 100 times better.
Want to take this farther?.. Visit a local broadcast station-
I have never known a station master who wouldn’t drop whatever and show me their station-- and if their engineer is there,, ask questions. Look at the transmitter, the cables, the tower--take it all in and meld it into what you been studying,-- then go home and put those ideas to use.
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I used to give similar tours of our facilities before the 9-11 craziness put a security end to it all… but I know those tours opened many eyes to ideas, ideas impossible to convey in photos, print or idle chat…

At least this works for me, and my Higher Powers think it must also… for I’m on my way to tour the next Marvel
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………………….CF

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**I can’t bring myself to use the term Lightning Protection for I don’t believe it can ever be 100%