[Lightning rods for my house? Or too "old fashioned"?

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Sandtrap
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[Lightning rods for my house? Or too "old fashioned"?

Post by Sandtrap » Wed Jan 10, 2018 7:56 pm

DW and I watched our neighbor's million dollar home burn all night after a lighting strike hit the roof and penetrated to the attic. He had a lighting rod system though I don't know the effectiveness. The home was very large and when fully involved, the fire crews could do nothing except contain the blaze. By morning there was nothing.

My home in Northern Arizona is 3 stories high, stucco, concrete, ceramic/cementuous heavy tile roof, in the middle of 50 acres of flat land. Great for birds and owls. Maybe not so great for lightning strikes. Lighting has struck land around us and it is extreme, especially summer monsoon season.

A neighbor and I have been talking about lighting rods and other types of systems.
I don't know if anyone still does those things as the last time I heard of a "lighting rod" was in a Ray Bradbury Book (Something Wicked This Way Comes :shock: . . ).

Actionably: Is this a concern? Does anyone here have a lighting rod or other system of this? Or is it just old fashioned?

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j :D
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Re: Noise in my attic

Post by likegarden » Thu Jan 11, 2018 9:09 am

We live in a 2-story home built in 1978 which has no lightning protection rods, but we have 4 large pine trees, aluminum gutters, downspouts and siding. Since our house has no lightning protection, there must be no code requirement to install them. I lived in a 4 story apartment building in Europe, and that house had lightning rods. Here is a reference to what lightning protection for a home might include.

http://www.northeastlightning.com/house ... -ma-ri-ny/

I just drove around developments with 2 story houses, no trees and all houses built on several acres of bare ground. None had lightning protection as shown in above web site.
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Re: [Lightning rods for my house]

Post by LadyGeek » Thu Jan 11, 2018 4:16 pm

Sandtrap wrote:
Wed Jan 10, 2018 7:56 pm
Actionably: I'd like advice on that but maybe it should be on another actionable thread?
I split the discussion into a new thread. If you want to change the thread title further, just edit the Subject: line in Post #1.
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Re: [Lightning rods for my house]

Post by Epsilon Delta » Thu Jan 11, 2018 4:50 pm

While I've never had a lightning rod per se, one house did have a TV antenna that was connected by 0 gauge copper wire to three ten-foot copper pipes driven into the ground. I'm fairly certain it would function just fine as a lightning rod to protect the house, although not the TVs. It was never struck. Not really surprising given the many taller trees and hills that were nearby.

The need for lightning protection depends on the exposure, which is a function of the location and of the prominence of the building. For most houses it would be insurance against a very unlikely event.

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Re: [Lightning rods for my house]

Post by Sandtrap » Thu Jan 11, 2018 9:08 pm

LadyGeek wrote:
Thu Jan 11, 2018 4:16 pm
Sandtrap wrote:
Wed Jan 10, 2018 7:56 pm
Actionably: I'd like advice on that but maybe it should be on another actionable thread?
I split the discussion into a new thread. If you want to change the thread title further, just edit the Subject: line in Post #1.
Always to the rescue.
I watched my neighbor's million dollar house burn down last year, all night. It was terrifying. Lighting.
thanks again,
j

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by 2comma » Thu Jan 11, 2018 11:18 pm

I don't think their old fashioned our newish office complex had them on all of the walkways connecting buildings (and I think on the building themselves) but I haven't seen any on a newer house. As a sailing enthusiast I do hear/read about boats, not just sailboats, getting hit fairly frequently and it usually takes out several of the expensive electronics. Our little 17 footer got hit and it looked like it hit the mast, came down one of the stays (wire that holds the mast up from the side), ran out of wire so it jumped to the water leaving a 18" hole in the hull. There is an industry built around lightning protection but I'll bet many are hocus-pocus and I've never found much evidence that mankind really understands lightning to this day. It would be hard to prove empirically that a system works - how would you test that?

I do believe there is something to them but I'd guess you'd need heavy gauge wire wire running as straight as possible directly to ground. As I understand it if there is a sharp turn in the wire the current might just decide to keep moving straight ahead.

Remember the old saying lightning never strikes twice. Well, I read an article about the empire state building and it's been hit many, many times. I'm sure it as some type of lightning protection and it must work because you never hear of any skyscraper getting significant damage from a lightening strike.

Anyway, I think they would look cool on your house!
Last edited by 2comma on Fri Jan 12, 2018 6:55 pm, edited 1 time in total.
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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by Watty » Thu Jan 11, 2018 11:41 pm

In the 1990's my parents had lightning rods put on their midwest house after the next door neighbors house was struck by lighting and had major damage. A few years before another house a block or two away had also been struck by lighting but only had very minor damage.

You could call your insurance company to ask what sort of discount you will get if you add them that that could give you a clue as to how much of a difference they make in your area. They likely also have specific requirements to get any discount so you should find that out before your buy them.


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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by vitaflo » Fri Jan 12, 2018 12:24 am

I do storm spotting for the National Weather Service. While most of my training on lighting is about lightening safety, I have done further studies into lightening strikes.

In short, while lightening rods may work, there's no guarantee they will, even if you have them installed. This is simply because of how lightening works. A typical cloud-to-ground bolt is a series of steps, starting with a leader, that moves in segments. Each segment is about 150 feet long, and they can branch like a tree (you've seen this in photos). It continues trying to find the path of least resistance until it's 150 feet from something on the ground. At this point an upward leader can occur (say from a house) and make a connection. This is the lightening strike.

The 150 foot segment is important because it means the ground could be hit and something very tall near it could be missed entirely if it's beyond this limit. It also means lightening can strike very far away from a cloud because of the branching effect. While something tall (like a lightening rod) has more potential to be hit, it's not a guarantee. It's possible the upward leader could come from the edge of your house instead of the lightening rod because it's closer to the final 150 foot segment than your lightening rods are. The distance matters in the end, not the height (though tall object have more potential to be hit because there's less of them around as the bolt works its way down to the ground).

Also keep in mind that most lightening strikes don't start fires like what happened to your neighbor. For that to happen you need many pulses of lightening on the same spot for it to usually get hot enough. Everything happens so fast in lightening but a strike can be one stroke, or as many as 20 in a row as the electrical energy dissipates. You've probably seen this if you've seen a bolt flash and strobe quickly as it strikes. It's the later ones that are the problem for starting fires, because they keep the energy on a single spot for a long enough time to cause combustion.

We've had a couple lightening strikes in our neighborhood on houses that have caused fires. One was surrounded by a grove of trees much taller than the house (which should act as natural lightening rods). Didn't matter. All I can say is if it makes you sleep better at night, look into it, but at the end of the day, whether you get hit or not basically comes down to dumb luck. And having rods installed is no guarantee that they will be effective. Mother nature doesn't care.

By the way the material of your roof doesn't matter. Lightening isn't attracted to metal. It's attracted to whatever is closest. Lightening rods are metal because they allow you to move the electricity after the hit away from the structure to the ground (path of least resistance). That path may not mean you steer clear of damage. If you get hit, you are likely to blow out all the electronics in your house regardless. Though obviously that's better than a fire.

If you want to see what a lightening strike looks like in super slow motion, here's a good example:

https://www.youtube.com/watch?v=dukkO7c2eUE

Note how it branches in tons of different directions as it travels down, and how it looks like a step pattern and a tree. Also notice how when it finally hits, all the branches that didn't make ground contact get "sucked in" and are now part of the main lightening strike. That's how it works. All of those potential other branches never actually reach a target. Instead they become part of the flow with the branch that hit. This is why I say a lightening strike is a bit of dumb luck. For every place that gets hit, there are dozens of others that could have, but didn't, based on geography, topology, surroundings, what have you.

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by lthenderson » Fri Jan 12, 2018 9:10 am

I live in the midwest and still see lightening rods installed but they aren't like the 3 to 4 feet tall poles at the highest point of the house like the houses used to have when I was a kid. These days they are less than a foot tall and you see them spaced out every 10 to 15 feet along the ridge of a home. They are easy to miss from the road and thus perhaps the appearance that people don't use them anymore when they are in fact fairly prevalent.

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by zed » Fri Jan 12, 2018 9:45 am

Since we're on the topic of lightning, here's one more thing for homeowners to worry about.

Flexible Gas Lines a Possible Fire Hazard

"Elizabeth George of Fishers, Ind., never gave much thought to her natural gas lines until lightning struck her neighbor's house in June and it burned to the ground. One month later, George's house nearly suffered the same fate when lightning struck her house but didn't catch it on fire.

Now her gas lines are foremost in her mind. "Every time we hear about a storm, we've got to worry about it," she says. "It's terrible that we have to live like this."

That's because both George and her neighbor have gas lines made of Corrugated Stainless Steel Tubing, or CSST.

It isn't the biggest fire hazard in your house, but improperly installed CSST might be the biggest fire hazard you've never heard of in your house. Since being introduced in the United States in 1988, it has become an increasingly popular way to deliver natural gas. Manufacturers estimate that more than 50 percent of all new houses with natural gas, or about 500,000 houses a year, include CSST.



https://www.angieslist.com/articles/fle ... hazard.htm

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by epictetus » Fri Jan 12, 2018 10:34 am

vitaflo,
thank you for that description of how lightening strikes work. I had no idea.
Focus on what you can control

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by Sandtrap » Fri Jan 12, 2018 2:04 pm

Thanks, that's perfect.
The second link doesn't seem to work.
j :D

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by Sandtrap » Fri Jan 12, 2018 2:06 pm

zed wrote:
Fri Jan 12, 2018 9:45 am
Since we're on the topic of lightning, here's one more thing for homeowners to worry about.

Flexible Gas Lines a Possible Fire Hazard

"Elizabeth George of Fishers, Ind., never gave much thought to her natural gas lines until lightning struck her neighbor's house in June and it burned to the ground. One month later, George's house nearly suffered the same fate when lightning struck her house but didn't catch it on fire.

Now her gas lines are foremost in her mind. "Every time we hear about a storm, we've got to worry about it," she says. "It's terrible that we have to live like this."

That's because both George and her neighbor have gas lines made of Corrugated Stainless Steel Tubing, or CSST.

It isn't the biggest fire hazard in your house, but improperly installed CSST might be the biggest fire hazard you've never heard of in your house. Since being introduced in the United States in 1988, it has become an increasingly popular way to deliver natural gas. Manufacturers estimate that more than 50 percent of all new houses with natural gas, or about 500,000 houses a year, include CSST.



https://www.angieslist.com/articles/fle ... hazard.htm
Spooky :shock:
This is similar to the shift from copper water lines to Pex tubing.
j :D

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by Sandtrap » Fri Jan 12, 2018 2:09 pm

vitaflo wrote:
Fri Jan 12, 2018 12:24 am
I do storm spotting for the National Weather Service. While most of my training on lighting is about lightening safety, I have done further studies into lightening strikes.

In short, while lightening rods may work, there's no guarantee they will, even if you have them installed. This is simply because of how lightening works. A typical cloud-to-ground bolt is a series of steps, starting with a leader, that moves in segments. Each segment is about 150 feet long, and they can branch like a tree (you've seen this in photos). It continues trying to find the path of least resistance until it's 150 feet from something on the ground. At this point an upward leader can occur (say from a house) and make a connection. This is the lightening strike.

The 150 foot segment is important because it means the ground could be hit and something very tall near it could be missed entirely if it's beyond this limit. It also means lightening can strike very far away from a cloud because of the branching effect. While something tall (like a lightening rod) has more potential to be hit, it's not a guarantee. It's possible the upward leader could come from the edge of your house instead of the lightening rod because it's closer to the final 150 foot segment than your lightening rods are. The distance matters in the end, not the height (though tall object have more potential to be hit because there's less of them around as the bolt works its way down to the ground).

Also keep in mind that most lightening strikes don't start fires like what happened to your neighbor. For that to happen you need many pulses of lightening on the same spot for it to usually get hot enough. Everything happens so fast in lightening but a strike can be one stroke, or as many as 20 in a row as the electrical energy dissipates. You've probably seen this if you've seen a bolt flash and strobe quickly as it strikes. It's the later ones that are the problem for starting fires, because they keep the energy on a single spot for a long enough time to cause combustion.

We've had a couple lightening strikes in our neighborhood on houses that have caused fires. One was surrounded by a grove of trees much taller than the house (which should act as natural lightening rods). Didn't matter. All I can say is if it makes you sleep better at night, look into it, but at the end of the day, whether you get hit or not basically comes down to dumb luck. And having rods installed is no guarantee that they will be effective. Mother nature doesn't care.

By the way the material of your roof doesn't matter. Lightening isn't attracted to metal. It's attracted to whatever is closest. Lightening rods are metal because they allow you to move the electricity after the hit away from the structure to the ground (path of least resistance). That path may not mean you steer clear of damage. If you get hit, you are likely to blow out all the electronics in your house regardless. Though obviously that's better than a fire.

If you want to see what a lightening strike looks like in super slow motion, here's a good example:

https://www.youtube.com/watch?v=dukkO7c2eUE

Note how it branches in tons of different directions as it travels down, and how it looks like a step pattern and a tree. Also notice how when it finally hits, all the branches that didn't make ground contact get "sucked in" and are now part of the main lightening strike. That's how it works. All of those potential other branches never actually reach a target. Instead they become part of the flow with the branch that hit. This is why I say a lightening strike is a bit of dumb luck. For every place that gets hit, there are dozens of others that could have, but didn't, based on geography, topology, surroundings, what have you.
Wow!
A lightning 101 lesson.
A bit terrifying :shock:
thanks for the education and video.
will pass it on to DW.
j :D

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by t3chiman » Fri Jan 12, 2018 3:24 pm

"...My home in Northern Arizona is 3 stories high, stucco, concrete, ceramic/cementuous heavy tile roof, in the "\middle of 50 acres of flat land...."
Short answer: you are a target. Longer answer: Depending on your home's framing and external wiring, you may not need further lightning protection.
I am a professional engineer (PE) and a licensed amateur radio operator. I know the physics of atmospheric electricity, and I have witnessed, closeup and real-time, the damage that a lightning strike can do. It's actually very interesting. The earth is forever leaking electrons back into the ionosphere. Thermal currents and molecular friction combine to return the accumulated charges back to earth, thus addressing the charge imbalance. Of course, the leakage is microamperes per square meter, and the lightning bolt delivers 10,000 to 100,000 Amperes over a few milliseconds (The ramp to peak in a few microseconds is particularly dramatic.)
Now, your power, phone, and cable TV providers have dealt with this problem for over a century. Take a look outside and see. Your power line poles all have an overhead protective wire ("Static wire"). At the base of the pole, the static wire is routed into the earth ("grounded"). If things are as I am describing, probably you are OK; the power line grounding will protect you.
If, OTOH, you are really the sore thumb in the neighborhood, your situation is potentially more dire. Imagine that your house, the highest structure for miles around, is overshadowed by a thundercloud that has transported its positive charges to the top of the cloud, and thus, by induction, has lots of negative charges on its base (I am simplifying the physics here to Benjamin Franklin levels.). The negatively charged cloud base induces an electric field across the space between itself and your house's chimney. Could be great enough to start static electric streamers dancing along your roofline (Or, strong enough to make your hair stand on end, if you were naive enough to go walking in the thunderstorm). At a certain, dramatic moment, the air's insulating ability is overwhelmed by the induced electric field, and the electrons in the cloud base come crashing back to earth.
Localized heating caused by the current will boil any water along its path to ground. Tree trunks explode; building walls collapse; people, well, it's best not to think about it.
If you give the current a place to go, it will go there. So, a couple of rods on the high points of your house is a good start. You have to connect them together, and you have to get the current from the rods into the ground. And you have to connect all the "grounds" in your system together. No good having "grounds" at different potential levels--that's what makes current flow.
Hope I have not been discouraging or frightening. Lightning is a fascinating subject.
Good luck. Your place sounds like the ultimate retreat.

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by Sandtrap » Fri Jan 12, 2018 3:27 pm

t3chiman wrote:
Fri Jan 12, 2018 3:24 pm
"...My home in Northern Arizona is 3 stories high, stucco, concrete, ceramic/cementuous heavy tile roof, in the "\middle of 50 acres of flat land...."
Short answer: you are a target. Longer answer: Depending on your home's framing and external wiring, you may not need further lightning protection.
I am a professional engineer (PE) and a licensed amateur radio operator. I know the physics of atmospheric electricity, and I have witnessed, closeup and real-time, the damage that a lightning strike can do. It's actually very interesting. The earth is forever leaking electrons back into the ionosphere. Thermal currents and molecular friction combine to return the accumulated charges back to earth, thus addressing the charge imbalance. Of course, the leakage is microamperes per square meter, and the lightning bolt delivers 10,000 to 100,000 Amperes over a few milliseconds (The ramp to peak in a few microseconds is particularly dramatic.)
Now, your power, phone, and cable TV providers have dealt with this problem for over a century. Take a look outside and see. Your power line poles all have an overhead protective wire ("Static wire"). At the base of the pole, the static wire is routed into the earth ("grounded"). If things are as I am describing, probably you are OK; the power line grounding will protect you.
If, OTOH, you are really the sore thumb in the neighborhood, your situation is potentially more dire. Imagine that your house, the highest structure for miles around, is overshadowed by a thundercloud that has transported its positive charges to the top of the cloud, and thus, by induction, has lots of negative charges on its base (I am simplifying the physics here to Benjamin Franklin levels.). The negatively charged cloud base induces an electric field across the space between itself and your house's chimney. Could be great enough to start static electric streamers dancing along your roofline (Or, strong enough to make your hair stand on end, if you were naive enough to go walking in the thunderstorm). At a certain, dramatic moment, the air's insulating ability is overwhelmed by the induced electric field, and the electrons in the cloud base come crashing back to earth.
Localized heating caused by the current will boil any water along its path to ground. Tree trunks explode; building walls collapse; people, well, it's best not to think about it.
If you give the current a place to go, it will go there. So, a couple of rods on the high points of your house is a good start. You have to connect them together, and you have to get the current from the rods into the ground. And you have to connect all the "grounds" in your system together. No good having "grounds" at different potential levels--that's what makes current flow.
Hope I have not been discouraging or frightening. Lightning is a fascinating subject.
Good luck. Your place sounds like the ultimate retreat.
Thanks so much for taking the time to teach me.
Is this a job for an electrician or are there 'lighting" professionals?
j :D

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by t3chiman » Fri Jan 12, 2018 3:55 pm

"...Is this a job for an electrician or are there 'lighting" professionals?..."
Google shows these guys, who seem professional: Classic Lightning Protection.
Can't hurt to call them.
HTH

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by Earl Lemongrab » Fri Jan 12, 2018 4:15 pm

Reminds me of the Livesoft "averse"/"adverse" thread. The word is lightning, not lightening. The latter is something very different.
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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by oldcomputerguy » Fri Jan 12, 2018 4:22 pm

vitaflo wrote:
Fri Jan 12, 2018 12:24 am
By the way the material of your roof doesn't matter. Lightening isn't attracted to metal. It's attracted to whatever is closest. Lightening rods are metal because they allow you to move the electricity after the hit away from the structure to the ground (path of least resistance). That path may not mean you steer clear of damage. If you get hit, you are likely to blow out all the electronics in your house regardless.
Absolutely. Some years ago we took a lightning hit on the tower in our parking lot (TV station with a 100' tower supporting microwave dishes). The tower itself was thoroughly grounded. But the hit leaked over onto the cables running into the building. That hit took out literally every piece of electronic equipment (computers, printers, dial-up modem, monitors, everything) within a 50' distance of building ingress, plus it damaged PCs in departments two floors up an 150 feet away. It took us two weeks just to find all the damaged equipment.

The point is, lighting is absolutely unpredictable, and there's really nothing you can put in place that will be guaranteed to prevent damage. That being said, proper lightning guards and good solid grounding can go a certain way toward lessening the chances of damage.
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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by alex_686 » Fri Jan 12, 2018 4:30 pm

Informative and funny and mostly on topic:

https://what-if.xkcd.com/16/

How dangerous is it, really, to be in a pool during a thunderstorm? —Jay Gengelbach

What would happen if you were taking a shower when you were struck by lightning? Or standing under a waterfall? —same3chords

What would happen if you were in a boat or a plane that got hit by lightning? Or a submarine? —SoobNauce

What if you were changing the light at the top of a radio tower and lightning struck? Or what if you were doing a backflip? Or standing in a graphite field? Or looking straight up at the bolt? —Danny Wedul

What would happen if lightning struck a bullet in midair? —Timothy Campbell

What if you were flashing your BIOS during a thunderstorm and you got hit by lightning? —njsg

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by t3chiman » Fri Jan 12, 2018 5:26 pm

oldcomputerguy wrote:
Fri Jan 12, 2018 4:22 pm
..., lighting is absolutely unpredictable, and there's really nothing you can put in place that will be guaranteed to prevent damage. That being said, proper lightning guards and good solid grounding can go a certain way toward lessening the chances of damage....
For sure, lightning is dramatic. And the way it jumps around, and melts/explodes stuff in its path, gives rise to a sense of tragic helplessness. But, really, it's just electricity. And regular folks can and do control the current flow, and mitigate the resulting damages.
Without delving too much into current rise times and flashover phenomena, one can gain a fair amount of insight from one basic principle: keep everything at "the same" potential during a strike. The steps involved: bond internal structures together, so that they remain at the same potential; bond outside conductors together for the same reason; connect internal and external bonds at one point; connect that point to earth.
Take a look at W8JI's amateur radio station lightning protection scheme. [https://www.w8ji.com/lightning.htm]
He is extreme, no doubt. And it is not cheap to get such a level of protection. If you want more detailed information, a lot of hams are professional cell tower engineers; they routinely install hundreds of towers that get thousands of strikes per year. They would be fired if the cell equipment were to be damaged during every thunderstorm. Their essays on the topic are instructive; google is your friend.
We have wandered a bit off topic, apologies.

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by JPH » Fri Jan 12, 2018 5:37 pm

I'm curious about the TV dish antenna that sits on my roof. Could that thing act as a lightning rod? Or maybe as a lightning attractor?
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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by jucor » Fri Jan 12, 2018 5:45 pm

Earl Lemongrab wrote:
Fri Jan 12, 2018 4:15 pm
Reminds me of the Livesoft "averse"/"adverse" thread. The word is lightning, not lightening. The latter is something very different.
Although you must admit that a house struck by lightning may well be quite lightened. :D :shock:

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by familytruckster » Fri Jan 12, 2018 6:05 pm

Sandtrap wrote:
Wed Jan 10, 2018 7:56 pm

Actionably: Is this a concern? Does anyone here have a lighting rod or other system of this? Or is it just old fashioned?
Do you know if your neighbor's house was properly grounded to meet current building codes? Is your house properly grounded to meet code? If you are out in the stix, out in the open, off grid, and/or on a septic system and you just witnessed your neighbor's home get destroyed by lighting, I would suggest contacting an electrician to verify that your house is properly grounded as a starting point. I think the current building code provide adequate grounding for the off chance of a nearby lightning strike, but your exposure sounds atypical.

I remember seeing my neighbors house after a lightning strike to their chimney . I was only 4 or 5 years old, but I still remember the house looking like it had melted in the middle and the chimney basically melted into a pillar of shiny pottery. The outside of the house was completely intact. It was really surreal.

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by vitaflo » Fri Jan 12, 2018 6:26 pm

JPH wrote:
Fri Jan 12, 2018 5:37 pm
I'm curious about the TV dish antenna that sits on my roof. Could that thing act as a lightning rod? Or maybe as a lightning attractor?
Nothing really "attracts" lightening. As I noted above, lighting will basically strike whatever is closest to one of its leaders. Many times that's something that's high up (because there are less high up things), but sometimes it's not.

Could your dish act as a lightening rod? Sure, and if it gets hit it will blow out all the electronics in your house. But this isn't much different than if lightning hit the ground near your house and traveled via ground currents into your electrical box. By the way, those ground currents are what are deadly if you're outside in the thunderstorm. You don't need to be struck directly to get fried. The current travels along the ground surface when the lightning hits, it doesn't go down into the ground.

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by bertilak » Fri Jan 12, 2018 8:09 pm

I saw one of those TV shows were they have various interesting scientific stories.

In this show a surveillance camera showed someone getting struck by lightning. It knocked him down but he got up and walked way. But that's not the amazing thing -- he got hit a second time only a few steps after that and got up again and walked away again -- two strikes back-to-back and he survived.

The theory was that it was raining and his wet clothes acted something like a Faraday cage and routed the worst of it around the outside of his body. They set up an experiment at one of these places that use a gigantic Van de Graaff generator to produce artificial lightning and tried it out on a dummy with an embedded ammeter. When the dummy was dry it got a lethal dose but if they "rained" on the dummy throughout the experiment the dose was less than lethal.
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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by just frank » Sat Jan 13, 2018 7:59 am

bertilak wrote:
Fri Jan 12, 2018 8:09 pm
I saw one of those TV shows were they have various interesting scientific stories.

In this show a surveillance camera showed someone getting struck by lightning. It knocked him down but he got up and walked way. But that's not the amazing thing -- he got hit a second time only a few steps after that and got up again and walked away again -- two strikes back-to-back and he survived.

The theory was that it was raining and his wet clothes acted something like a Faraday cage and routed the worst of it around the outside of his body. They set up an experiment at one of these places that use a gigantic Van de Graaff generator to produce artificial lightning and tried it out on a dummy with an embedded ammeter. When the dummy was dry it got a lethal dose but if they "rained" on the dummy throughout the experiment the dose was less than lethal.
I'm a bit skeptical of this. Fresh water like rain is a poor conductor, while salt water like our insides is a good conductor.

I always thought the strike survivor stories were just people hit (or near) the low current leader, and which never got a high current return bolt.

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by bertilak » Sat Jan 13, 2018 8:07 am

just frank wrote:
Sat Jan 13, 2018 7:59 am
bertilak wrote:
Fri Jan 12, 2018 8:09 pm
I saw one of those TV shows were they have various interesting scientific stories.

In this show a surveillance camera showed someone getting struck by lightning. It knocked him down but he got up and walked way. But that's not the amazing thing -- he got hit a second time only a few steps after that and got up again and walked away again -- two strikes back-to-back and he survived.

The theory was that it was raining and his wet clothes acted something like a Faraday cage and routed the worst of it around the outside of his body. They set up an experiment at one of these places that use a gigantic Van de Graaff generator to produce artificial lightning and tried it out on a dummy with an embedded ammeter. When the dummy was dry it got a lethal dose but if they "rained" on the dummy throughout the experiment the dose was less than lethal.
I'm a bit skeptical of this. Fresh water like rain is a poor conductor, while salt water like our insides is a good conductor.

I always thought the strike survivor stories were just people hit (or near) the low current leader, and which never got a high current return bolt.
I doubt the dummy was made with salt-watery insides so you may have something there. In any case, the video of the incident was impressive.
May neither drought nor rain nor blizzard disturb the joy juice in your gizzard. -- Squire Omar Barker, the Cowboy Poet

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by likegarden » Sat Jan 13, 2018 10:40 am

In my area lightning bolts happen when it rains. So when a lightning hits my house and it rained on the dusty roof, aluminum siding, gutters and downspouts, it might only do little damage - I hope. I also have then those wet 100 ft pines 25 ft away.

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by Sandtrap » Sat Jan 13, 2018 10:44 am

likegarden wrote:
Sat Jan 13, 2018 10:40 am
In my area lightning bolts happen when it rains. So when a lightning hits my house and it rained on the dusty roof, aluminum siding, gutters and downspouts, it might only do little damage - I hope. I also have then those wet 100 ft pines 25 ft away.
We have foothills and also a stream nearby. They regularly get hit by lighting during the summer monsoons.
It is scary.
I thought that having nonflammable surfaces on my home would help but am not sure. Ceramic/cement tile roofing, stucco exterior. Nothing to burn.
Or perhaps that's a faulty premise.

But I don't know if this helps reduce conductivity and therefore not as strike prone?

My home is somewhat large and 3 stories high so I would surmise that a "lighting rod" system would be "Bogle expensive".
j :D

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by thx1138 » Sat Jan 13, 2018 12:19 pm

vitaflo wrote:
Fri Jan 12, 2018 6:26 pm

Nothing really "attracts" lightening. As I noted above, lighting will basically strike whatever is closest to one of its leaders. Many times that's something that's high up (because there are less high up things), but sometimes it's not.
For "negative" strokes (leader moves from cloud to ground) that's correct. That is 90% of lightening strokes and almost all of the strokes a house on average terrains is going to see.

For "positive" strokes (leader moves from ground to cloud) things are much, much different. First the strike will be to the "highest" point over quite a large area. Second the leader starts at the ground and thus whatever creates the highest local field strength to ionize the air will cause the leader to begin there. So for a positive stroke it is much more predictable where the strike will hit and it can be controlled more.

A radio antenna on a hill or mountain will end up "attracting" all the positive strokes from quite a large area and thus will get hit by many, many more strikes than anything lower. While positive strokes are only 10% of the strikes if you are collecting them from a square mile footprint while negative strokes only accumulate on high targets within a few hundred feet footprint the highest terrain will in fact see many more strikes than anywhere else.

Positive strokes also tend to carry significantly higher current and contain many more individual flashes following the same leader. As a result lightening protection for an average building is a very different proposition than for one on the top of a hill or mountain.

We lived in AZ for awhile with all those monsoon storms. I computed our home an a low ridge should expect a lightening strike about once every hundred years. That's kind of the same probability that determines whether you need flood insurance and so I concluded that's why homes in AZ tend not to have lightening protection - cheaper to just take the occasional bad luck.

Put your house on top of the highest point within a mile and the odds change dramatically because of the difference between how positive and negative strokes behave. You might very well want protection in that situation.

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Re: [Lightning rods for my house? Or too "old fashioned"?

Post by stan_the_man » Sat Jan 13, 2018 9:04 pm

Watty wrote:
Thu Jan 11, 2018 11:41 pm
In the 1990's my parents had lightning rods put on their midwest house after the next door neighbors house was struck by lighting and had major damage. A few years before another house a block or two away had also been struck by lighting but only had very minor damage.

You could call your insurance company to ask what sort of discount you will get if you add them that that could give you a clue as to how much of a difference they make in your area. They likely also have specific requirements to get any discount so you should find that out before your buy them.
I wouldn't ask that exact question. Maybe ask IF there is a discount for having lightning rods.

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