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Lightning Protection for IP cameras/camera power

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Hi,

 

I'm playing around with a few IP cameras here at home and had some questions about best practices with regard to protecting my data and camera power systems from lightning induced surges.

 

So far I've installed several IP (megapixel) cameras at various locations both inside buildings and under the eaves. I'm driving everything off of an altronix 24vac supply with 8 fused outputs. The Altronix is plugged into an APC NS1250 to surge protect the system and keep the cameras alive during power outages.

 

The NVR and switch is plugged in to a different APC NS1250. Everything's powered by a GFCI circuit. The data system is shared with our dsl connection and home computers.

 

I'm considering mounting a camera along my back fence line. This camera would be about 120' from the nearest building. Planning this installation got me thinking about lightning and I realized I don't have a very good grasp of best practices with regard to limiting lightning damage in my system.

 

My focus so far has been on the fence line camera since it would be mounted up on a wooden post away from buildings (probably disguised as a wooden birdhouse for aesthetic reasons). Data and power to that camera would be run above ground along the wooden fence. I have started to wonder a bit about the rest of my system as well.

 

For the outside fenceline camera, I ordered a couple of 100mb Cat5 to Fiber media converters and a fiber patch cord. My plan was to run the data line in outdoor rated cat5 from the camera to a point inside the building, through the fiber to isolate any induced surges, then into my switch.

 

Some questions that I'm puzzling over are:

 

Controlling Surges on the DATA side:

 

1. I'm pretty sure the fiber interconnect is about as good as I can get for surge isolation on the data side. Is this right?

 

2. Is it acceptable practice to carry the copper into the building and jump to the fiber interconnect inside, or should I figure out how to make that break outside the building?

 

3. I've started to wonder about existing buried cat5 between buildings. I’ve currently got a few cat5 cables installed between buildings in PVC buried 3-4’ over 20’-30’ runs. Does the burial depth mitigate any lightning surge danger there, or do I need to seriously consider pulling fiber in those conduits instead?

 

4. I’m also wondering about outside cameras mounted under the eaves. Should these be considered a risk similar to the fenceline camera with regard to carrying lighting surges into the network?

 

5. If the answer to #4 is yes then do you have any suggestions for isolating them? Perhaps a dedicated switch for the cameras tied to the main switch with a gigabit fiber interconnect?

 

Controlling Surges on the POWER Side:

 

1. I’m running 16/2+ground for camera power pretty much direct from the Altronix to the fenceline camera (as well as the others). The ground line is bonded at the altronix to the building ground. Am I exposing all the cameras powered by the Altronix to simultaneous lightning damage if a single camera is struck or has an induced surge in the power line?

 

2. If the answer to #1 is yes, then are there ways to mitigate this risk? I could swallow toasting a single camera due to a strike, but I'd like to lower any risk of simultaneously smoking all the cameras tied to the power supply if possible or practical.

 

I'd welcome any suggestions you might have on all this. I do worry I've got just enough knowledge here to get me in trouble.

 

Thanks

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Hi,

 

I'm playing around with a few IP cameras here at home and had some questions about best practices with regard to protecting my data and camera power systems from lightning induced surges.

 

So far I've installed several IP (megapixel) cameras at various locations both inside buildings and under the eaves. I'm driving everything off of an altronix 24vac supply with 8 fused outputs. The Altronix is plugged into an APC NS1250 to surge protect the system and keep the cameras alive during power outages.

 

The NVR and switch is plugged in to a different APC NS1250. Everything's powered by a GFCI circuit. The data system is shared with our dsl connection and home computers.

 

I'm considering mounting a camera along my back fence line. This camera would be about 120' from the nearest building. Planning this installation got me thinking about lightning and I realized I don't have a very good grasp of best practices with regard to limiting lightning damage in my system.

 

My focus so far has been on the fence line camera since it would be mounted up on a wooden post away from buildings (probably disguised as a wooden birdhouse for aesthetic reasons). Data and power to that camera would be run above ground along the wooden fence. I have started to wonder a bit about the rest of my system as well.

 

For the outside fenceline camera, I ordered a couple of 100mb Cat5 to Fiber media converters and a fiber patch cord. My plan was to run the data line in outdoor rated cat5 from the camera to a point inside the building, through the fiber to isolate any induced surges, then into my switch.

 

In regards to lightning strikes unless your cameras are mounted on an extremely high fence I wouldn't worry about it. If you fence is chain link you could bond the fence to a ground rod at some point along the fence. The same goes for poles which have cameras on them. As for induced interference into buried Category cable due to lightning strikes into the earth a shielded Category cable is more then sufficient. Properly installed you should have no problems.

 

Some questions that I'm puzzling over are:

 

Controlling Surges on the DATA side:

 

1. I'm pretty sure the fiber interconnect is about as good as I can get for surge isolation on the data side. Is this right?

 

Fiber is the best communication cable for rejecting noise since it is an insulator it can not conduct electricity.

 

2. Is it acceptable practice to carry the copper into the building and jump to the fiber interconnect inside, or should I figure out how to make that break outside the building?

 

I would take the fiber right to your network switch and use a short patch cable between your media converters and your switch. How are you going to connect the fiber converter at the camera side?

 

3. I've started to wonder about existing buried cat5 between buildings. I’ve currently got a few cat5 cables installed between buildings in PVC buried 3-4’ over 20’-30’ runs. Does the burial depth mitigate any lightning surge danger there, or do I need to seriously consider pulling fiber in those conduits instead?

 

You can always put in some inline surge suppression as there is no need to install fiber. I am sure some people might disagree with me on this. The biggest thing I have found is during lightning strikes induced ESD can cause an unstable network connection. http://www.tripplite.com/en/products/model.cfm?txtModelID=151

 

4. I’m also wondering about outside cameras mounted under the eaves. Should these be considered a risk similar to the fenceline camera with regard to carrying lighting surges into the network?

 

Lighting is going to hit the highest point. It will hit the roof of the building first before it hits the camera under the eaves.

 

5. If the answer to #4 is yes then do you have any suggestions for isolating them? Perhaps a dedicated switch for the cameras tied to the main switch with a gigabit fiber interconnect?

 

Controlling Surges on the POWER Side:

 

1. I’m running 16/2+ground for camera power pretty much direct from the Altronix to the fenceline camera (as well as the others). The ground line is bonded at the altronix to the building ground. Am I exposing all the cameras powered by the Altronix to simultaneous lightning damage if a single camera is struck or has an induced surge in the power line?

 

What size is the ground? What is the ground connected to on the camera side? All grounds for lightning protection should be a minimum of #6.

 

2. If the answer to #1 is yes, then are there ways to mitigate this risk? I could swallow toasting a single camera due to a strike, but I'd like to lower any risk of simultaneously smoking all the cameras tied to the power supply if possible or practical.

 

I'd welcome any suggestions you might have on all this. I do worry I've got just enough knowledge here to get me in trouble.

 

Thanks

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Above post pretty much covers it. I have cameras mounted on a 50' tower, which itself is about 20' taller than the next nearest structure, and the most protection it has is a lightning rod that sticks up 10' or so above the cameras themselves, and a solid ground connection from the tower to a 10'-deep grounding rod. This is in an area that does get a fair number of storms, and it's never had a problem (or even been hit, that I'm aware of, but then again, the only way I'd be aware of it would probably be if it did sustain some damage).

 

One thing to remember with lightning, is that it can do some weird, weird stuff, seemingly outside the laws of physics... you could spend thousands of dollars and countless hours protecting against it, and still have equipment fried by some bizarre lightning behaviour - in other words: by all means, take precautions, but don't go too far out of your way agonizing over it, because if lightning wants to get your toys, it WILL find a way

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Thanks for the feedback. It's easy to get overly worried reading about this on the internet. Kind of like reading bear attack stories before going to Alaska.

 

I'm mostly trying not to do something really stupid to myself.

 

As to dmillers questions.

 

The fence is 8' wood, the post for the camera will be about 12-14'

 

I'm running unshielded copper cat 5 from the camera back to the building (above ground along the fence). I bought 2 $50 cat5->fiber media converters and a 6' fiber patch cord. I was going to run 120' of copper from the camera into one media converter, through the fiber to the next media converter, then on to my main switch with copper. I figured 6' of glass would stop a surge leaving only the camera and 1 media converter at risk.

 

I wondered whether to put the first media converter outside the building and run the fiber through the wall or whether it was ok to run copper from the camera directly inside to the first media converter.

 

Sounds like my data side is probably ok.

 

On the power side I'm still not clear if a surge would be likely to run back up the power cable to the altronix power supply then back out the other 24vac power feeds to the rest of the cameras. It seems to me that everything tied to that power supply would be at risk.

 

The camera takes 24VAC and has provision for a ground. Manufacturer says use of the ground is optional, but I went ahead and home run tied it to my building ground on the other cameras since it was there. Been using 16 ga for that. Clearly not a lightning protection type of ground.

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Thanks for the feedback. It's easy to get overly worried reading about this on the internet. Kind of like reading bear attack stories before going to Alaska.

 

I'm mostly trying not to do something really stupid to myself.

 

As to dmillers questions.

 

The fence is 8' wood, the post for the camera will be about 12-14'

 

It the fence post is the highest object around for some distance then you need to ad lightning rods however I highly doubt it is. The lightning rods would have to be bonded with a #6 coper conductor to a ground rod at the base of the post.

 

I'm running unshielded copper cat 5 from the camera back to the building (above ground along the fence). I bought 2 $50 cat5->fiber media converters and a 6' fiber patch cord. I was going to run 120' of copper from the camera into one media converter, through the fiber to the next media converter, then on to my main switch with copper. I figured 6' of glass would stop a surge leaving only the camera and 1 media converter at risk.

 

You probably don't want to hear this but I would forget about using the fiber converters all together and run Cat5e Underground shielded or some Industrial Cat5E shielded and properly ground the shield at the house to ground. You will prevent any unwanted ESD protecting to the switch and camera. You have a better chance of winning the lotto then getting a lightning strike hit to your camera on you fence. If you are really worried about lightning strikes then you need lightning rods.

 

I wondered whether to put the first media converter outside the building and run the fiber through the wall or whether it was ok to run copper from the camera directly inside to the first media converter.

 

Sounds like my data side is probably ok.

 

On the power side I'm still not clear if a surge would be likely to run back up the power cable to the altronix power supply then back out the other 24vac power feeds to the rest of the cameras. It seems to me that everything tied to that power supply would be at risk.

 

The camera takes 24VAC and has provision for a ground. Manufacturer says use of the ground is optional, but I went ahead and home run tied it to my building ground on the other cameras since it was there. Been using 16 ga for that. Clearly not a lightning protection type of ground.

 

A 16AWG will do nothing for a lightning strike. The wire will burn up and the current will have no where to go but through other equipment rather then to ground. For correct lightning protection you need lightning rods grounded with a #6 to ground. The purpose of the lightning rods to to prevent the strike from ever getter to the equipment. Any previsions you take at the equipment for lightning strikes will never be enough.

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There are some trees nearby much taller than the fence.

 

I can always find something to do with the fiber converters--maybe I need a network drop out in the field somewhere...

 

I'll run down some shielded cat5 as you suggest, I think.

 

Thanks for the help on this.

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I'm running unshielded copper cat 5 from the camera back to the building (above ground along the fence). ...

A 16AWG will do nothing for a lightning strike. The wire will burn up and the current will have no where to go but through other equipment rather then to ground. For correct lightning protection you need lightning rods grounded with a #6 to ground. The purpose of the lightning rods to to prevent the strike from ever getter to the equipment. Any previsions you take at the equipment for lightning strikes will never be enough.

 

From an article entitled "Protecting Electrical Devices from Lightning Transients" in Electrical Engineering Times, an 18 AWG (lamp cord) wire will conduct approaching 60,000 amps without melting. However, we usually use 12 AWG or larger to conduct lightning harmlessly to earth on signal wires. 6 AWG or larger for AC electric.

 

Lightning does not strike a highest point. Lightning locates and conducts through a best conductor from cloud to earth. If that path is through a CCTV camera, then the camera is damaged. If the best connection is from a camera, through Cat 5, then through a switch, to earth inside the building, then the switch is probably damaged.

 

Protection is never about stopping a surge. Protection is always about connecting lightning (and all other surges) to earth on a path that is not destructive. For example, this professional's application note demonstrates entitled "The Need for Coordinated Protection" demonstrates the concept:

http://www.erico.com/public/library/fep/technotes/tncr002.pdf

 

Two structures demonstrated. Both must have their own single point earth ground. Any wire entering either structure must first connect low impedance (ie 'less than 10 foot') to that single point ground before entering.

 

In your case, a camera remote from the building would be a separate structure much like that antenna tower. A Cat5 wire entering that camera must first be earthed. All eight wires must connect to the camera's single point ground before connecting to the camera. Since none of the wires can connect directly, then a surge protector does what a wire would otherwise do. An example of a CAT5 protector that has a green wire for earthing. A dedicated wire that must connect low impedance (as short as possible) to the earth ground before that wire rises up to connect to the camera:

http://www.tripplite.com/en/products/model.cfm?txtModelID=151

 

Does not matter if Cat5 wire is overhead or underground. It will still carry a surge into the building (or camera) if not first connected (every wire in that cable) to single point ground.

 

Same solution applies to other wires entering a building. If any wire does not make that short connection to earth, then all protection is compromised. Protection means no energy is inside a building (or camera). Once energy gets inside, then it hunts for earth destructively. Your solution is always about earthing that energy before it gets inside.

 

In a similar situation, FIOS boxes were destroyed by a lightning strike. How can this be when FIOS if fiber optic? Simple. The homeowner had all but invited lightning to enter the house. So it found earth destructively via a FIOS ONT box. Incoming on AC mains. Destructively through a computer and printer that were on a power strip protector. Then destructively through a router and FIOS boxes to earth.

 

Once that energy is permitted inside, then nothing can stop a destructive hunt for earth. In this case, the strip protector bypassed protection inside the computer and multifunction printer. I repaired that multifunction printer by literally removing semiconductors in that surge path. Restored the printer by following the incoming and outgoing surge path from protector to FIOS interface boxes.

 

That is how you avert surge damage. Any path that might connect to earth via electronics must be earthed BEFORE it gets to electronics. Best earthing is from each cable with a short as possible wire (12 AWG or larger). Any conductor that cannot be earthed directly by a wire (telephone, AC electric, Cat5) must be earthed by a protector.

 

If the application note does not make it obvious, each structure must have a single point ground. All earthing must be to the same electrode. To make those two earth grounds better, the note suggests a buried ground wire interconnecting tower and building grounds. You might do same with an interconnecting ground wire between the building's single point ground and the distant camera's single point ground.

 

This is just introductory concept. Far more may be necessary as installation details are made apparent. But the concept applies to all surge protection. Either the surge is earthed harmlessly by the lowest impedance connection. Or that surge goes hunting for earth destructively via electronics. Protection is always defined by a connection to and quality of earth ground. A protector is only a connecting device. Does what a direct wire connection might otherwise do.

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As a rule, I put surge suppression on everything going outside. Nothing's going to stop a direct lightening strike (except fiber), but a nearby strike can cause some surges and other stuff with all the static involved. Even the buried cable, water or even a shovel could theoretically cause a short.

 

The following produce good surge protectors for cat5, power cables, coax, 120vac, whatever else you might have:

http://www.ditekcorp.com/products.asp

http://www.protectiongroup.com/Surge

 

 

Since you're in Alaska, your other option is to move to the north slope where I was told lightening doesn't exist.

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I'm running unshielded copper cat 5 from the camera back to the building (above ground along the fence). ...

A 16AWG will do nothing for a lightning strike. The wire will burn up and the current will have no where to go but through other equipment rather then to ground. For correct lightning protection you need lightning rods grounded with a #6 to ground. The purpose of the lightning rods to to prevent the strike from ever getter to the equipment. Any previsions you take at the equipment for lightning strikes will never be enough.

 

From an article entitled "Protecting Electrical Devices from Lightning Transients" in Electrical Engineering Times, an 18 AWG (lamp cord) wire will conduct approaching 60,000 amps without melting. However, we usually use 12 AWG or larger to conduct lightning harmlessly to earth on signal wires. 6 AWG or larger for AC electric.

 

 

I would never use a 12AWG to connect a lightning rod to ground. I have seen some lightning rods with upto a 4/0 copper conductor to a ground grid consisting of 4 10' ground rods. You might use a 12AWG to bond a telephone line to ground but where I am from you can't even do that anymore as you require a #6 as a minimum.

 

 

Lightning does not strike a highest point. Lightning locates and conducts through a best conductor from cloud to earth. If that path is through a CCTV camera, then the camera is damaged. If the best connection is from a camera, through Cat 5, then through a switch, to earth inside the building, then the switch is probably damaged.

 

 

 

You are correct to say that lightning takes the path of least resistance; however, the path of least resistance is the highest point as air is one of the best insulators out there.

 

 

 

Protection is never about stopping a surge. Protection is always about connecting lightning (and all other surges) to earth on a path that is not destructive. For example, this professional's application note demonstrates entitled "The Need for Coordinated Protection" demonstrates the concept:

http://www.erico.com/public/library/fep/technotes/tncr002.pdf

 

Two structures demonstrated. Both must have their own single point earth ground. Any wire entering either structure must first connect low impedance (ie 'less than 10 foot') to that single point ground before entering.

 

In your case, a camera remote from the building would be a separate structure much like that antenna tower. A Cat5 wire entering that camera must first be earthed. All eight wires must connect to the camera's single point ground before connecting to the camera. Since none of the wires can connect directly, then a surge protector does what a wire would otherwise do. An example of a CAT5 protector that has a green wire for earthing. A dedicated wire that must connect low impedance (as short as possible) to the earth ground before that wire rises up to connect to the camera:

http://www.tripplite.com/en/products/model.cfm?txtModelID=151

 

Does not matter if Cat5 wire is overhead or underground. It will still carry a surge into the building (or camera) if not first connected (every wire in that cable) to single point ground.

 

Same solution applies to other wires entering a building. If any wire does not make that short connection to earth, then all protection is compromised. Protection means no energy is inside a building (or camera). Once energy gets inside, then it hunts for earth destructively. Your solution is always about earthing that energy before it gets inside.

 

In a similar situation, FIOS boxes were destroyed by a lightning strike. How can this be when FIOS if fiber optic? Simple. The homeowner had all but invited lightning to enter the house. So it found earth destructively via a FIOS ONT box. Incoming on AC mains. Destructively through a computer and printer that were on a power strip protector. Then destructively through a router and FIOS boxes to earth.

 

Once that energy is permitted inside, then nothing can stop a destructive hunt for earth. In this case, the strip protector bypassed protection inside the computer and multifunction printer. I repaired that multifunction printer by literally removing semiconductors in that surge path. Restored the printer by following the incoming and outgoing surge path from protector to FIOS interface boxes.

 

That is how you avert surge damage. Any path that might connect to earth via electronics must be earthed BEFORE it gets to electronics. Best earthing is from each cable with a short as possible wire (12 AWG or larger). Any conductor that cannot be earthed directly by a wire (telephone, AC electric, Cat5) must be earthed by a protector.

 

If the application note does not make it obvious, each structure must have a single point ground. All earthing must be to the same electrode. To make those two earth grounds better, the note suggests a buried ground wire interconnecting tower and building grounds. You might do same with an interconnecting ground wire between the building's single point ground and the distant camera's single point ground.

 

This is just introductory concept. Far more may be necessary as installation details are made apparent. But the concept applies to all surge protection. Either the surge is earthed harmlessly by the lowest impedance connection. Or that surge goes hunting for earth destructively via electronics. Protection is always defined by a connection to and quality of earth ground. A protector is only a connecting device. Does what a direct wire connection might otherwise do.

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Lightning does not strike a highest point. Lightning locates and conducts through a best conductor from cloud to earth. If that path is through a CCTV camera, then the camera is damaged. If the best connection is from a camera, through Cat 5, then through a switch, to earth inside the building, then the switch is probably damaged.

 

You are correct to say that lightning takes the path of least resistance; however, the path of least resistance is the highest point as air is one of the best insulators out there.

 

The highest point is not necessarily the "path of least resistance" - a 50' high metal tower will probably be a more attractive target than a 60' high tree nearby. And remember too, the HIGHEST point from the ground won't necessarily be the CLOSEST to the point of highest charge in the cloud.

 

Once again, lightning can be a very odd an unpredictable creature...

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The highest point is not necessarily the "path of least resistance" - ... the HIGHEST point from the ground won't necessarily be the CLOSEST to the point of highest charge in the cloud.

 

Quite true. Top of a mountain is not most often struck. A mountain's side is more often struck. Lightning hunts for a better path from cloud to earthborne charges. Often a streambed is struck rather than mountains on either side. Geology rather than distance is a more likely reason for lightning strikes.

 

In FL, a house was struck repeatedly on its one wall. They installed lightning rods. Lightning again struck the wall; ignored the rods.

 

That wall contained bathroom plumbing. Lightning rods were only earthed in sand by eight foot ground rods. The plumbing connected to deeper and more conductive soils. That earthing was improved so that lightning rods would perform protection.

 

Lightning is not capricious. It only appears to be capricious when humans fail to learn simple principles. Most assume lightning entered on the cable wire, destroy a TV, and stops. Assume because the cable connection was destroyed. That assumption, in violation of basic science, makes lightning unpredictable. First that electric current is everywhere in a path from cloud to earth. Later, something in that path fails. In the TV example, current was not incoming on the properly earthed cable. Lightning far down the street found a best path to earth via AC electric, inside the house, through a TV, and out to earth via the cable wire. Damage was on the TV's outgoing path to earth - the TV cable connection. Surge was not incoming on the TV cable as most would assume.

 

All three examples demonstrate what so many don't learn. And why so many assume lightning is capricious. Explains why so many would buy a magic box to do protection when its manufacturer does not even claim that protection in spec numbers. Protection always starts by defining a destructive path to earth. Then replacing that path with a more conductive and harmless connection to earth.

 

Learn from damage. Lightning is never capricious. It's just that most homeowners forget basic electrical concepts that were taught even in elementary school science. Therefore do not learn what the destructive path to earth was. Geology is a critically important consideration when determining where lightning might strike. And how to prevent future damage.

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Yes, good point: LIGHTNING may not be unpredictable, but the terrain and conditions can be, which effectively makes lightning's behavior unpredictable. The house with the plumbing is an example: once the conditions were understood (the well-grounded plumbing in the target wall), then it all made perfect sense, but without that study (which was only undertaken once initial mitigation efforts with poorly-grounded lightning rods failed), the behavior couldn't be accurately predicted.

 

As far as lightning being attracted to trees: remember that wood is also a good insulator... and one of the best insulators is WATER. Yes, pure water actually a very good insulator; it's impurities such as minerals and metals in the water that make it conductive. A rain-wet tree COULD be attractive to lightning depending on what other impurities are present, but inherently, the wood and water themselves should not attract lightning.

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As far as lightning being attracted to trees: remember that wood is also a good insulator...

Let's put some numbers to that word 'insulator'. Back in 1750, lightning was seeking earth ground. A better connection to earth was wooden church steeples. Wood is an electrical conductor for that 20,000 amps. But wood is not a very good conductor. 20,000 amps through wood creates a high voltage. 20,000 amps times a high voltage is high energy. A wooden church steeple is destroyed.

 

Franklin put a lightning rod atop that steeple. The rod does not do protection. A connection to earth and the earthing electrode do the protection. 20,000 amps via a conductive wire to earth means low voltage. 20,000 amps times a low voltage is low energy. Nothing is damaged.

 

Everything conducts electricity. The word 'insulator' must be used in context. When discussing lightning, then everything is conductive. Just that some things (air, deionized water) are less conductive. Sometimes called an insulator.

 

Air is one of the best insulators. And yet lightning uses air as an electrical conductor. Perspective is best defined by numbers. Numbers are critical to understanding a solution.

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Air is one of the best insulators. And yet lightning uses air as an electrical conductor

 

Sort of. The insulating capacity of air allows charges to build, but at the moment of a strike, the lighting is traveling through air that has been ionized/broken down into plasma which is conductive.

 

One comment here did strike me though is

 

Protection is never about stopping a surge. Protection is always about connecting lightning (and all other surges) to earth

 

I was definitely thinking about this a little backwards. Seems like a fiber patch between the outside cable and my network would likely stop the surge from following the data into the switch, but clearly I need to also provide a path for that surge to follow otherwise the next step a surge might take could be as undesirable as smoking my network. I hadn't quite thought that through.

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Since you're in Alaska, your other option is to move to the north slope where I was told lightening doesn't exist.

 

Nah, we've even got lightning up there now. Courtesy of global warming according to the eggheads up at the university.

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Above post pretty much covers it. I have cameras mounted on a 50' tower, which itself is about 20' taller than the next nearest structure, and the most protection it has is a lightning rod that sticks up 10' or so above the cameras themselves, and a solid ground connection from the tower to a 10'-deep grounding rod. This is in an area that does get a fair number of storms, and it's never had a problem (or even been hit, that I'm aware of, but then again, the only way I'd be aware of it would probably be if it did sustain some damage).

 

when you are talking about lightning protection the first thing you need to look is your surrounding area. you may have a 40 feet structure yet you will not need that protection if the buildings or structures around the structures are higher and have lighting protection. my point is, you must think about this if you are thinking of making a cost effective system with good protection. still, for a better practice you can have this protection. for additional information you can have a look in this following site:

 

http://www.rfimmunity.com/

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