Lightning strike issue
- Thread starter JamesR
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JamesR
Getting the hang of it
Yep, good advice. I will pull the cover off of the main panel and the sub panel across the other side of the basement and check ALL breaker connections and wiring. I will just kill the mains, verify no AC present and check them all.
I pulled that one camera from its mount and it has a nasty arc mark on it. When I shake the turret it sounds like it is full of sand.
JamesR
Getting the hang of it
Got the new NVR today. 5 of the 7 cameras are good. 2 got toasted. I popped one open and have never such electronic death before. It looks like charcoal. Looks like a fireball was in there. I killed the main power to the house and checked every breaker and each outlet that had a dead device on it. All looked good. Ran 2 new CAT6 runs for the replacement cameras (on order). Still researching a simple practical way to surge protect at least the NVR from voltage spikes coming in on the LAN cables.
fenderman
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Insane!
Might want to inspect your roof and exterior of house for lighting damage. Looks to have got you pretty good. If you look around your property you can probably find the strike marks.
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usaf_pride
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You can get LAN lighting protectors, but you need them on both ends of longer runs (150' or so). You will need to watch out as some of them only have protection on 6 wires vs. all 8 and be sure that you get a POE compatible device. The only real way to protect the NVR is to optically isolate the circuits. This would basically involve running all the cables to a POE switch that has a fiber portand then getting a transceiver and connect that to your NVR. Keep in mind that the POE switch would probably become the sacrificial lamb in this setup. (products linked for reference only and not a recommendation)
Unless you live in a high activity area for lightning, the costs of trying to protect may be more than the replacement. Nothing is going to stop the direct/close hits from doing damage. Something will be sacrificed to the lightning gods, you just need to determine what it is going to be (if it ever happens again).
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JamesR
Getting the hang of it
I looked over the roof and exterior of the house briefly yesterday as well as the area of those cameras in the attic. All looks normal. The soffit was slightly dislodged at one camera and there is black residue on the soffit where one was mounted but that is all I can see. I will have a closer look today.
I have fixed most everything else so far... replaced the logic pcb's in the microwave and garage door opener, bought a used replacement Yamaha receiver, got new modem/router stuff from the cable company. They come out tomorrow to replace my TiVo boxes.
I ordered 1 of the new LTS full color 24/7 turret cameras. CMIP3C42W-M It is a 4MP, 4mm. Should give me full color at night, no IR. I saw the demo video of it from the LTS parking lot and it looked pretty good so I will give it a test. I can return if I do not like it. I will post up some image captures of it once installed.
I have fixed most everything else so far... replaced the logic pcb's in the microwave and garage door opener, bought a used replacement Yamaha receiver, got new modem/router stuff from the cable company. They come out tomorrow to replace my TiVo boxes.
I ordered 1 of the new LTS full color 24/7 turret cameras. CMIP3C42W-M It is a 4MP, 4mm. Should give me full color at night, no IR. I saw the demo video of it from the LTS parking lot and it looked pretty good so I will give it a test. I can return if I do not like it. I will post up some image captures of it once installed.
J Sigmo
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Hopefully you will get some coverage from your home insurance. You may well end up needing to have the entire house rewired to make it safe.
Carbon tracks and breakdowns in insulation could make for well-hidden faults that won't show up right away, and be located within finished areas where you can't see them unless you do some demolition.
The insurance folks may well insist that you have a lot of rewiring done to make the house safe for the future.
Lightning protection is not commonly practical or practiced in residential construction, or even typical commercial/industrial construction.
Where I used to work, we installed a lot of radio repeater sites and telemetry systems. Where my son worked, they did all of the Motorola commercial and public safety communication systems for several states.
Surprisingly, you can set up tower and building sites that will withstand repeated, frequent direct lightning hits. But this design philosophy is rarely seen outside of the communication industry.
Think about where radio and television transmitting stations, or commercial/public safety radio communication and telemetry repeaters are located.
You put them on the highest mountaintops in the areas they serve to get as close to "line of sight" RF paths as you can, and the largest coverage area possible. If the land is flat, you put up very tall towers to achieve the same sorts of paths.
The result is that, inevitably, your radio site is the highest, most likely target for atmospheric discharges in the area. And as a result, many sites can expect direct strikes hundreds of times per year.
And yet, damage that takes such a site off the air is rare. So the question is: How do they do it?
The answer is found in concepts related in a lot of the posts people have made already in this thread.
You must avoid a situation where there is a path through your building and equipment for the lightning energy to "want to" flow.
And to that end, among other things, you must avoid having more than one "ground" point available within a facility.
This is a lot like laying out a printed circuit board for sensitive analog signals. You must employ single-point grounding and avoid any "daisy chaining" of ground connections. That way, currents flowing from, for example, a digital switching device that generates sharp spikes of ground current, won't flow through the same ground path as a sensitive analog signal reference. If those noisy currents can flow through a ground path shared by the analog signal reference point, the voltage dropped through the resistance of that ground path will appear at that analog signal point, with respect to "ground", and create noise, or even induce oscillations, etc.
Anyhow...
What we did when setting these sites up, was to pound in 25 to 30 ground rods in a ring around the building (radio shack). These ground rods were then connected with a continuous ring of 1000mcm or larger copper wire, which was exothermally welded (see Cadweld) to each rod.
This established something of a ground connection to the earth in the area. It usually still sucked, though! You just cannot really connect to the earth very well anywhere, and especially not in the dry, rocky soil of a mountaintop. If I recall correctly, they strived for an earth ground resistance of 25 ohms or less.
Ground rods are generally a joke. Frequently, bags of rock salt would be placed at each ground rod to slowly dissolve and leach into the rocky ground to try to improve the conductivity, but when things are dry, there's just no way you will really achieve a good "ground".
The fact is that the earth is made of largely insulating materials. Dry rock doesn't conduct. Lots of it is as good as glass, actually. Pounding a rod into a bed of dry sand or rock is pointless. But hey, it's code, so it's dutifully done, anyhow. And it's better than nothing. Sometimes, at least.
Yes, if the soil is wet, and loaded with dissolved metal salts, it will have free ions that can conduct to some degree, so that's what we hope for. But don't count on it!
So the idea of "earth ground" isn't this absolute thing people imagine it to be. The earth, at any point, will exhibit various "bulk resistivity". And the patterns and swirls of conductivity in a given volume of earth will be complex and rather chaotic.
So what happens when lightning strikes the earth?
The current flows outward from the point of contact in a pattern determined by the resistances it encounters as it spreads and tries to find paths to the average potential in the earth that is different from that of the lightning bolt itself. The goal is to equalize the potential between the charged regions in the clouds and what it "sees" as the different potential in the earth. When these charges come close enough to equilibrium, the arc will stop. Or sometimes, the charge exchange will go too far, and then the potential will be reversed, and current will flow the other direction for a while. Sometimes a resonance is created, and you get the current snapping back and forth a few times as the system "rings".
But the thing to envision is that as this current spreads out within the earth, the high current flowing through this messy volume of random resistances will create voltage drops across these resistances.
And when you're talking about tens of thousands of amps, and substantial resistances, these voltage gradients within the earth are huge.
So ground rods even a few feet from each other can have tens of thousands of volts appear between them instantly as the current pulse spreads out through the soil.
This is why the advice, when lightning is imminent and you cannot get to shelter, is to crouch down into a ball, with your feet as close together as possible. You don't want the distance between your feet to "see" a high voltage between them in the ground such that you become a preferred (lower resistance) path for the charge to take if a strike hits nearby.
So back to our radio site.
What is commonly done is that this "ring-of-ground" is crappy, but it's better than nothing. And when we bond the base of our radio tower to this "ground", we can expect that all of the current from every lightning strike that WILL hit our tower will find it's way to "earth" through this path that we've created. It sucks, but it's the best thing in the area.
Still, let's say this lightning bolt has a peak current of 10,000 amps. (Some are a lot more).
And let's say we managed to achieve a resistance to "earth ground" of a very respectable 20 ohms.
By good old Ohm's Law, we see that at the instant of the lightning strike, the voltage between our extensive grounding system and the "earth" will be 200,000 volts!
Well crap! How can our equipment survive?
The answer is that we establish a good single point ground for the building.
A copper plate, perhaps 1/4" thick, and a foot or two square is mounted in the wall of our shack, at a point near the base of the tower. The coax from the various antennas on the tower enter the building through surge suppressors mounted in holes through this plate. The same goes for all utilities entering the building.
Water, gas, power, phone, internet, our antennas. Everything that could conduct electricity enters through this one big, thick, copper plate, and is bonded to it. Any coax or multi-conductor cable enters through surge arrestors that mount to this plate.
Everything that needs a ground inside the building has an insulated (isolated) ground wire all of it's own that goes to this ground plate, with as few bends, and as smooth and wide radius bends as possible to reduce inductance. Some things get grounding straps that are made of wide, flat strips of copper, etc., to reduce both resistance and inductance in those paths.
No daisy-chaining of grounds are allowed. Separate isolated grounds only.
This establishes our entry plate as THE one and only ground reference for the site.
The idea is that even at the instant when "our ground" is possibly tens or hundreds of thousands of volts away from "earth ground", there should be no potential between our various pieces of equipment. It is the potential seen across or through equipment that causes destructive currents to flow through the equipment.
This is just like static protection protocol for electronic gear. You never hand someone a circuit board because at the instant when you are both touching it at the same time, the board becomes the path through which your bodies' charges will equalize. Zap!
Always set the board down (on a safe surface) and let the other person pick it up.
Anyhow, it is possible to set up a site to be very well protected from lightning.
But other than ham radio folks or commercial radio nerds, I never see people building their houses or even businesses this way. But you really should! Most architects and contractors would look at you really funny, but this really is good practice.
You should probably also wire the whole place using isolated grounds (like hospitals do).
The EMP from the nearby strikes can be shielded against, too, but nobody does that for their house, either. And that may well be going too far.
Lightning sucks. We had some lightning damage where I work a few weeks ago. We had very little damage compared to what could have happened, but did have a bit of work to do afterwards. It could have been a lot worse.
I have tried to do what I can to make the things I have control over be as safe as practically possible.
But the main parts of the plant were never really built with lightning protection considered.
At some point, it's just beyond practicality for most installations. For those radio sites, it's required, or they won't last the first summer.
Carbon tracks and breakdowns in insulation could make for well-hidden faults that won't show up right away, and be located within finished areas where you can't see them unless you do some demolition.
The insurance folks may well insist that you have a lot of rewiring done to make the house safe for the future.
Lightning protection is not commonly practical or practiced in residential construction, or even typical commercial/industrial construction.
Where I used to work, we installed a lot of radio repeater sites and telemetry systems. Where my son worked, they did all of the Motorola commercial and public safety communication systems for several states.
Surprisingly, you can set up tower and building sites that will withstand repeated, frequent direct lightning hits. But this design philosophy is rarely seen outside of the communication industry.
Think about where radio and television transmitting stations, or commercial/public safety radio communication and telemetry repeaters are located.
You put them on the highest mountaintops in the areas they serve to get as close to "line of sight" RF paths as you can, and the largest coverage area possible. If the land is flat, you put up very tall towers to achieve the same sorts of paths.
The result is that, inevitably, your radio site is the highest, most likely target for atmospheric discharges in the area. And as a result, many sites can expect direct strikes hundreds of times per year.
And yet, damage that takes such a site off the air is rare. So the question is: How do they do it?
The answer is found in concepts related in a lot of the posts people have made already in this thread.
You must avoid a situation where there is a path through your building and equipment for the lightning energy to "want to" flow.
And to that end, among other things, you must avoid having more than one "ground" point available within a facility.
This is a lot like laying out a printed circuit board for sensitive analog signals. You must employ single-point grounding and avoid any "daisy chaining" of ground connections. That way, currents flowing from, for example, a digital switching device that generates sharp spikes of ground current, won't flow through the same ground path as a sensitive analog signal reference. If those noisy currents can flow through a ground path shared by the analog signal reference point, the voltage dropped through the resistance of that ground path will appear at that analog signal point, with respect to "ground", and create noise, or even induce oscillations, etc.
Anyhow...
What we did when setting these sites up, was to pound in 25 to 30 ground rods in a ring around the building (radio shack). These ground rods were then connected with a continuous ring of 1000mcm or larger copper wire, which was exothermally welded (see Cadweld) to each rod.
This established something of a ground connection to the earth in the area. It usually still sucked, though! You just cannot really connect to the earth very well anywhere, and especially not in the dry, rocky soil of a mountaintop. If I recall correctly, they strived for an earth ground resistance of 25 ohms or less.
Ground rods are generally a joke. Frequently, bags of rock salt would be placed at each ground rod to slowly dissolve and leach into the rocky ground to try to improve the conductivity, but when things are dry, there's just no way you will really achieve a good "ground".
The fact is that the earth is made of largely insulating materials. Dry rock doesn't conduct. Lots of it is as good as glass, actually. Pounding a rod into a bed of dry sand or rock is pointless. But hey, it's code, so it's dutifully done, anyhow. And it's better than nothing. Sometimes, at least.
Yes, if the soil is wet, and loaded with dissolved metal salts, it will have free ions that can conduct to some degree, so that's what we hope for. But don't count on it!
So the idea of "earth ground" isn't this absolute thing people imagine it to be. The earth, at any point, will exhibit various "bulk resistivity". And the patterns and swirls of conductivity in a given volume of earth will be complex and rather chaotic.
So what happens when lightning strikes the earth?
The current flows outward from the point of contact in a pattern determined by the resistances it encounters as it spreads and tries to find paths to the average potential in the earth that is different from that of the lightning bolt itself. The goal is to equalize the potential between the charged regions in the clouds and what it "sees" as the different potential in the earth. When these charges come close enough to equilibrium, the arc will stop. Or sometimes, the charge exchange will go too far, and then the potential will be reversed, and current will flow the other direction for a while. Sometimes a resonance is created, and you get the current snapping back and forth a few times as the system "rings".
But the thing to envision is that as this current spreads out within the earth, the high current flowing through this messy volume of random resistances will create voltage drops across these resistances.
And when you're talking about tens of thousands of amps, and substantial resistances, these voltage gradients within the earth are huge.
So ground rods even a few feet from each other can have tens of thousands of volts appear between them instantly as the current pulse spreads out through the soil.
This is why the advice, when lightning is imminent and you cannot get to shelter, is to crouch down into a ball, with your feet as close together as possible. You don't want the distance between your feet to "see" a high voltage between them in the ground such that you become a preferred (lower resistance) path for the charge to take if a strike hits nearby.
So back to our radio site.
What is commonly done is that this "ring-of-ground" is crappy, but it's better than nothing. And when we bond the base of our radio tower to this "ground", we can expect that all of the current from every lightning strike that WILL hit our tower will find it's way to "earth" through this path that we've created. It sucks, but it's the best thing in the area.
Still, let's say this lightning bolt has a peak current of 10,000 amps. (Some are a lot more).
And let's say we managed to achieve a resistance to "earth ground" of a very respectable 20 ohms.
By good old Ohm's Law, we see that at the instant of the lightning strike, the voltage between our extensive grounding system and the "earth" will be 200,000 volts!
Well crap! How can our equipment survive?
The answer is that we establish a good single point ground for the building.
A copper plate, perhaps 1/4" thick, and a foot or two square is mounted in the wall of our shack, at a point near the base of the tower. The coax from the various antennas on the tower enter the building through surge suppressors mounted in holes through this plate. The same goes for all utilities entering the building.
Water, gas, power, phone, internet, our antennas. Everything that could conduct electricity enters through this one big, thick, copper plate, and is bonded to it. Any coax or multi-conductor cable enters through surge arrestors that mount to this plate.
Everything that needs a ground inside the building has an insulated (isolated) ground wire all of it's own that goes to this ground plate, with as few bends, and as smooth and wide radius bends as possible to reduce inductance. Some things get grounding straps that are made of wide, flat strips of copper, etc., to reduce both resistance and inductance in those paths.
No daisy-chaining of grounds are allowed. Separate isolated grounds only.
This establishes our entry plate as THE one and only ground reference for the site.
The idea is that even at the instant when "our ground" is possibly tens or hundreds of thousands of volts away from "earth ground", there should be no potential between our various pieces of equipment. It is the potential seen across or through equipment that causes destructive currents to flow through the equipment.
This is just like static protection protocol for electronic gear. You never hand someone a circuit board because at the instant when you are both touching it at the same time, the board becomes the path through which your bodies' charges will equalize. Zap!
Always set the board down (on a safe surface) and let the other person pick it up.
Anyhow, it is possible to set up a site to be very well protected from lightning.
But other than ham radio folks or commercial radio nerds, I never see people building their houses or even businesses this way. But you really should! Most architects and contractors would look at you really funny, but this really is good practice.
You should probably also wire the whole place using isolated grounds (like hospitals do).
The EMP from the nearby strikes can be shielded against, too, but nobody does that for their house, either. And that may well be going too far.
Lightning sucks. We had some lightning damage where I work a few weeks ago. We had very little damage compared to what could have happened, but did have a bit of work to do afterwards. It could have been a lot worse.
I have tried to do what I can to make the things I have control over be as safe as practically possible.
But the main parts of the plant were never really built with lightning protection considered.
At some point, it's just beyond practicality for most installations. For those radio sites, it's required, or they won't last the first summer.
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JamesR
Getting the hang of it
J Sigmo, thanks for taking the time with that tutorial. I read through it twice. I guess I just got very unlucky with that strike. Not sure if a rack mounted POE surge/lightning protector would have helped or not. Wouldn't have prevented the hit but possibly may have saved the NVR. The cameras would still be toast though if hit directly.
Possibly this device for the cameras mounted outside to my soffits would save the NVR and other devices in the house on the same network? >>>> Indoor 8-Port Med Power 10/100 Base-T CAT5 Lightning Surge Protector - CMSP-CAT5-8
Possibly this device for the cameras mounted outside to my soffits would save the NVR and other devices in the house on the same network? >>>> Indoor 8-Port Med Power 10/100 Base-T CAT5 Lightning Surge Protector - CMSP-CAT5-8
J Sigmo
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L-Com makes good equipment. And that device might help a lot in many circumstances, especially if everything is set up properly.
But there are so many variables that it's hard to say if any given protective device will protect anything else in a system for a particular lightning event.
What a surge suppressor can do is to limit the voltages it "sees" between the various conductors it's protecting and what it "sees" as ground, and/or limit the voltages that appear between different conductors on its output side. That can be extremely helpful. But things need to be configured so that the surge protector's "ground" will be at the same potential as the protected equipment's "ground" during an event.
If you get a surge suppressor, make sure you follow the manufacturers recommendations for how to wire everything up and how to bond the grounds for the various devices.
Without doing the wiring, plumbing, etc., of a building with lightning protection in mind from the start, it's always hard to protect things as well as you might wish. And nothing guarantees that you won't have any damage.
There's a lot to all of this.
You used to be able to find a PDF of Motoroloa's guide for lighting protection. But I'm not finding it available anymore unless you pay for it.
I think this is an older version, in PDF format:
http://www.repeater-builder.com/antenna/site-stuff/are-fifty-six-man-2005.pdf
The IEEE also has a lightning protection design guide, but again, they want money for it these days. It may well be worth spending that money, especially if you're planning some construction.
IEEE 1692-2011 - IEEE Guide for the Protection of Communication Installations from Lightning Effects
This company makes excellent surge suppression equipment. We used a lot of their suppressors for our radio sites:
https://www.polyphaser.com/search?Category=RF+Surge+Protectors&sort=y&view_type=grid
https://www.polyphaser.com/surge-protector-accessories
https://www.polyphaser.com/search?Category=Data+Surge+Protectors&Dapssp99app=Ethernet&sort=y&view_type=grid
They have a lot of "white papers" on various surge protection, EMP protection, grounding, etc. Lots of good reading!
https://www.polyphaser.com/resources/white-papers
This one is great, concerning grounding systems for radio sites:
https://www.polyphaser.com/News/DownloadFile?downloadGuid=c68ebee3-baa1-470e-b61c-ac0bc2f97eba
They make the point that a lightning strike will create very high frequency components, and your ground system needs to have low inductance as well as low resistance to prevent high voltages from appearing between "ground" points.
This is very interesting, too:
https://www.polyphaser.com/News/DownloadFile?downloadGuid=784c41cb-1486-4961-876d-c3d810bcc0db
A LOT of good information is in the white papers at that site.
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usaf_pride
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Ultimately, in a direct/near strike, something will be sacrificed. It's just a mater of what
What's the opinion on these Tupavco Ethernet surge protectors with gas discharge tubes: https://www.amazon.com/Ethernet-Surge-Protector-Gigabit-1000Mbs/dp/B07GBLFFNK
I've been thinking of getting these. They don't have TVS diodes but these diodes fail anyway when overpowered and need to be huge in order to avoid overpowering.
I've been thinking of getting these. They don't have TVS diodes but these diodes fail anyway when overpowered and need to be huge in order to avoid overpowering.
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usaf_pride
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They will handle a 5,000A pulse with a 8/20uS wave form. It will provide some protection, but a direct or nearby strike will probably smoke right through it (20kA would be better). There is a lot of engineering behind lighting protection and a lot to understand on the specific standards. Here is an old article from ECM magazine that explains what the 8/20uS means (while talking about a new standard of testing).
Basically the 8uS is the time for the rated energy (5kA) to reach 90% of the peak (front edge) and the 20uS represents how long the energy takes to get to 50% (trailing edge). The 8/20uS is a testing standard to rate how well it will do at the rated amperage strike. So you must determine if a 5kA surge is representative of your area. Here is another detailed answer regarding the energy. This discussion is based more on utility power lines, but lets face it, they are a magnet for lightning and they have a lot of experience. @J Sigmo provided similar information is available on the radio/tv broadcast side.
Like I said, this is deep engineering. Ultimately, something is better than nothing. But the something may be nothing more than a placebo to ease your mind.
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knedit
Young grasshopper
jeez, those pictures. poor camera. Looks like you just got unlucky over all, glad there wasn't a fire. If lightning is common in your area then i think they do make surge protectors for ethernet cables.
After losing a number of switches, cameras and gate opener to a strike, I installed the Ubiquity surge protectors at each end of my long runs (main trunks between gate, barn, and home). I've had several storms, with very close strikes since installing them. Already twice I've lost the ports on the switches between the gate and the barn. From what I understand the Ubiquity is a cheap, sacrificial unit. Yet, they never triggered. Both still work, but the ports on the switches on either end of the cable went dark. Fortunately, I have the Netgear ProSafe lifetime warranty, and call to them had me new switches the next day, with a free return label (I cannot say enough good about Netgear and their warranty support!).
I'm no EE, but I'm inclined to believe that if lightning has your number, there's nothing you can do to stop it. In fact, given how little voltage/current it takes to damage switches, even if the protection worked as it should, the stray transient voltage is enough to zap consumer-level gear.
I cannot believe that my Dahua SD59225 took a hit large enough to blow the RJ45 connector off the end, and blast the cable in half, with no internal damage.
With all but a couple of cheap $20 switches, my loses were on equipment new enough to still have warranty, or lifetime warranty which covered the surges. I was really lucky.
I'm no EE, but I'm inclined to believe that if lightning has your number, there's nothing you can do to stop it. In fact, given how little voltage/current it takes to damage switches, even if the protection worked as it should, the stray transient voltage is enough to zap consumer-level gear.
I cannot believe that my Dahua SD59225 took a hit large enough to blow the RJ45 connector off the end, and blast the cable in half, with no internal damage.
With all but a couple of cheap $20 switches, my loses were on equipment new enough to still have warranty, or lifetime warranty which covered the surges. I was really lucky.
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