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How to Protect a Network Against Lightning? 120

Posted by Cliff from the that's-a-lot-of-unplugging-to-do dept.
RichiH asks: "The monsoon, started about a month early in India this year. While it is not sure if that is due to global warming or not, there are more pressing issues for the IT world at hand. Until about the end of July, there will be major thunderstorms in this area. How do you protect a network that is spread over 100 square kilometres in a land where the concept of a lightening arrestor is next to unknown? The network in question consists of about 2500 boxes of various kinds which are connected using 10BASE2 (aka BNC), 10BASE-T (aka RJ45) and 10BASE5 (aka thicknet), where only the last one may be new to some readers. The big question is: how can you protect yourself against these storms in a way that is both fast to implement and does not require laying of new lines?"
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How to Protect a Network Against Lightning? More

How to Protect a Network Against Lightning?

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  • Lightning protection (Score:3, Informative)

    by mknewman ( 557587 ) * on Tuesday May 11, 2004 @01:24PM (#9118381)
    Two words, lightning rod.
    • Outsource to country cheaper than India and reap the profits.
    • I am seeing a tall tree, a piece of surplus scrap metal, and a under-nourished Indian we like to call "Sparky".
      • Actually, understanding the teachings of Faraday [wikipedia.org] you would obviously not try to create a lightning 'rod' but would be much better off creating an environment that allowed the energy to come from any direction be dispersed over a large surface area and then be shunted into the common ground.

        Given this, I recommend you liberally wrap all the buildings in a highly conductive material such as copper or aluminum foil and perhaps put a nice big electricity conducting rod on top of that to try to attract the ele

    • Enormously Controversial (Score:4, Informative)

      by mosel-saar-ruwer ( 732341 ) on Tuesday May 11, 2004 @03:46PM (#9119813)

      Two words, lightning rod.

      Actually, among people who care about these sorts of things [and there are precious few in this business who give a damn], lightning rods, and, more generally, good grounding, are enormously controversial.

      Classically, the thinking was that a well grounded lightning rod served to divert voltage surges away from the interior of your structure and down to the groundwater, or, more specifically, to the ionized particles suspended in moist soil. [Oh, and, by the way, once the surge makes it to "groundwater," there's no guarantee it'll stay there; it's entirely possible that it'll decide it doesn't like groundwater and find an alternate route back into your structure. These phenomena generally fall under the title of "grounding loops."]

      However, there's a new school of thought which holds that a well-grounded lightning rod serves to ATTRACT voltage surges, and could cause a voltage surge to get nearer to your structure than would otherwise be the case. If you follow that approach, you want safety in numbers: You hope that there are enough targets out there that are well enough grounded that the voltage surge will be diverted towards them, rather than towards you.

      If you're interested in residential and light-commercial products, I can highly recommend the surge protectors of Panamax; in particulary, we've had a lot of luck with their Max 8 Coax product shielding broadband over coaxial cable:

      The Panamax products tend to work interior to a building. [By the way, as far as interior wiring is concerned, did you know that in three-color wiring, the white wire and the bare wire are connected to the same mount in your circuit breaker box? I.e., once you get inside a building, white and ground are one & the same.] For products exterior to a building, I'd take a look at Citel, of Miami, FL [especially their P8AX series for coaxial cable lines, although they have myriad products for POTS and CAT5, as well]:
      http://www.citelprotection.com [citelprotection.com]

      • the white wire and the bare wire are connected to the same mount in your circuit breaker box

        A few years ago, there was a change in the code, which now requires white and ground to be anchored to two different mounts, but in almost all existing construction, that won't be the case.

        • Actually no. NEC states that both uninsulated grounds and neutrals can be connected to the same bus bar. Both the ground bus bar and neutral bus bar are connected through the back of the panel. Best practice is to connect the ground homeruns on the bus bar physically connected nearest to the site ground cable and return ground to the pole; then connect the neutral homeruns on the far bus bar. I'm wiring a house as we speak so this is fresh in my mind. I thought I'd toss that into the discussion.
      • Here's the real scoop.

        The way a lightning rod works is that it provides a highly conductive path to ground that drains off charge (shorts it to ground, so to speak) before that charge builds up enough to achieve the difference in potential necessary for a lightning bolt. If the end that points up comes to a sharp point it does this better than if that end is rounded.

        The lightning rod is, of course, grounded, usually with very heavy gauge (i.e., low, low resistance) wire connecting it to a ground rod.

    • Recommended lightning rod usage:

      Install lightning rods on OTHER tall buildings within a 250-1000 metre radius of the building to be protected.

      Make sure that lightning rods + buildings end up much taller than the building to be protected.

  • Easy solution... (Score:5, Funny)

    by NetRanger ( 5584 ) * on Tuesday May 11, 2004 @01:26PM (#9118410) Homepage
    During monsoon season, outsource your IT operations to the United States.
  • Preferably Florida, they know lightning there.

    ;)
    • When I was working and going to school at Florida State University the CompSci and the Math building networks were connected via a strand of 10Base5 that got struck by lightning about once every 10 months toasting the transceivers on either end. After that happened about 5 times the replaced it with a strand of fiber, which at the time was pretty spendy.

      Not much help to you, but it tells you about the frequency of Florida Lightning.

  • WiFi (Score:4, Informative)

    by Ratso Baggins ( 516757 ) on Tuesday May 11, 2004 @01:27PM (#9118425) Homepage
    Sure your bandwidth is lower (in general), but you can't induce a current along a 2.5GHz wireless link...
    • ... or can you?!?
      • IIRC you can induce current along a plasma beam - is that what you were thinking?
      • Well you could technically, but the resistance is enormous. IIRC, it requires about 10,000 Volts per inch of air.

        • Great Scott, son, we're talking 1.21 JIGGA-watts here!

          • Exactly - lightning already has 10,000V times how ever many inches it's crossing (that's a lot of volts). But the point is, once it hits your WiFi device, it's gonna go for the path(s) of least resistance, not over the air again.
      • Being a Floridian, I can speak from experience: you most certainly can! While the V/inch is 10,000, Lightning is well over that threshhold, meaning that it can have a measurable effect at a distance. From my experience, having a strike 30 feet from a building, it not only came in through the WAN line, but also the power and phone, and blew anything hardwired to the LAN. It also blew all WiFi cards in the building, and in some cases, melted the antenna leads.

        Best thing for lightning, don't want it blown, do

    • Re:WiFi (Score:2, Informative)

      by Anonymous Coward
      Huh?
      Rf is basically AC current going thru the air.

      E=I*R, so, I=E/R

      E=the RF you transmit
      R=resistance of transmission media

      Since E isn't zero, and R isn't infinite, then there must be current (I) somewhere.

      • WiFi-Clearing the air. (Score:1, Informative)

        by Anonymous Coward
        Let's kill two birds with one stone.

        AC (Alternating Current) isn't the same thing as RF (Radio Frequency). Two the levels are so low that it's effectively irrelivent. Now if the RF energy was ionizing the air, you might have a path, but even TV stations don't do that.

        Poster two [slashdot.org]
        "All except for that great big metal and plastic rod sticking up that we call an antenna..."

        Not all antennas "stick up", and there are ways to minamize the effects of "sticking up". Remember lightening rods, and antennas work bec

    • Re:WiFi (Score:5, Informative)

      by cryptor3 ( 572787 ) on Tuesday May 11, 2004 @02:05PM (#9118839) Journal
      but you can't induce a current along a 2.5GHz wireless link...
      All except for that great big metal and plastic rod sticking up that we call an antenna...
    • Okay, correct me if I'm wrong, but this sounds like a horrible solution. Haven't you ever seen your tv blip or heard your radio go staticy during lightning? Lightning acts like a very large spark-gap transmitter. As we all know, spark-gap transmitters throw out nasty RF over several freqencies, and I don't think they discriminate against 2.5GHz.

      There are proper ways to protect a network against lightning, and there are halfass "solutions" like these. Make sure you do your research before choosing eithe

      • Re:WiFi (Score:3, Interesting)

        by rcw-home ( 122017 )
        Lightning acts like a very large spark-gap transmitter. As we all know, spark-gap transmitters throw out nasty RF over several freqencies

        s/several/all/

        Picture a lightning bolt. It's white, right? White is the sum of all colors. White (RF) noise is the sum of all frequencies.

  • Huh... (Score:4, Funny)

    by avalys ( 221114 ) * on Tuesday May 11, 2004 @01:30PM (#9118460)
    You're in India, you say?

    Actually, the safest way to protect your equipment against lightning strikes is wire a lightning rod directly into your network's central switch. The extra voltage and current from the lighting will safely disperse through all the attached systems, and you may even notice an increase in performance!

    Don't let anyone tell you otherwise.

    • Huh...Shock and awe. (Score:3, Informative)

      by Anonymous Coward
      Who moderated this informative? The individual is trying to be funny. As for the question. There's two ways, Containment, and isolation. Someone suggested wireless links. That will break some of the paths, but not others. The other is containment. Minimize the number of paths that lightening or a power surge can take. For example a whole house surge protector instead of a whole lot of little ones. A big surge protector at the demarcation point for the phone lines instead of a lot of smaller ones. There is o
      • I think the moderation of informative was a joke by the moderators. If you think about it was quite funny that not only was the post a joke but the moderation of informative played on that.
        • so when i get this in M2, what do I do?
          • I guess that just depends on if you think the moderators are allowed to partake in these types of jokes. If you think moderation is 100% serious and it was an inappropriate use of moderator points then mark it unfair. If you can't decide mark it no opinion, and if you think it was funny then mark it fair. I personally thought it was funny and would probably mark it as a fair moderation, but that's just me.

  • to obvious? (Score:4, Funny)

    by Councilor Hart ( 673770 ) on Tuesday May 11, 2004 @01:30PM (#9118465)
    euh... shouldn't you have thought of that before?
    Like, you know, at the time of installing the network?
    just asking, what do I know about stuff like this...
    • euh... shouldn't you have thought of that before?
      Like, you know, at the time of installing the network?
      just asking, what do I know about stuff like this...

      Since the network includes thicknet and BNC cabling, it's probably a mishmash of systems that's been pieced together over at least 20 years. It's probably been struck by lightning a few times, and only now do they have someone interested in minimizing damage.
  • There is just not enough detail in your post to give any more specific advise. But a quick way to isolate one segment of the network from another would be with a pair of wireless bridges (i.e. 802.11 "access points"). Maybe outside your budget, but they can be had for $100 each. Just make sure they have a bridging mode.

  • Lightning (Score:3, Informative)

    by NanoGator ( 522640 ) on Tuesday May 11, 2004 @01:36PM (#9118539) Homepage Journal
    " The big question is: how can you protect yourself against these storms in a way that is both fast to implement and does not require laying of new lines?"

    802.11 + a Pringles can!

  • The only reliable way to control lightning (Score:3, Funny)

    by jrivar59 ( 146428 ) on Tuesday May 11, 2004 @01:46PM (#9118627)
    How to pray [cptryon.org]

  • Cheap Hardware (Score:5, Interesting)

    by Micro$will ( 592938 ) on Tuesday May 11, 2004 @01:46PM (#9118631) Homepage Journal
    A few years ago my friend and I decided to set up a network between our houses. We ran about 200 feet of 10BASE2 along a fence and used an old 486 DX33 box on each end as transparent bridges between the cable and out LAN segments. Every once in a while we'd get a close lightning strike in the summer and it would fry one of the combo cards we used. Fortunately, they were old Linksys NE2000 compatable ISA cards I picked up used for about $2 each. I'd go through about 1 or 2 every year. I tried using a spark gap type arrestor, but it wasn't enough, besides a few bucks a year was worth it.
    • Do what the radio stations do. They loop their cable from the antenna right after the spark gap. That's it. Nothing fancy. It has worked since radio began.

      High voltage HATES inductance. One large diameter turn of the cable after the spark gap and the high voltage will absolutely refuse to take the extra millisecond required to build up the huge magnetic field around the coil.

  • Zounds! (Score:5, Funny)

    by daeley ( 126313 ) * on Tuesday May 11, 2004 @01:52PM (#9118704) Homepage
    IIRC Protection from Lightning is a 4th level Cleric spell!

    Geeks these days...
    • IIRC Protection from Lightning is a 4th level Cleric spell!

      And Raise Dead is a 5th level Cleric spell. Why bother continuously protecting against something that might happen occasionally, when it's just easier to fix the results after the fact? (Now if only there were a Raise Charred Metal spell...)
      • Haven't you ever heard of golems?
        Just get a lich or some master dwarves or something, I'm sure one of them will make a computer golem for you.
        • Haven't you ever heard of golems?

          Somehow, I'm not really thrilled at the thought of my Windows Media Player punching me in the face for 2d8+12 points of damage whenever I play an MP3 file for which I don't have a valid certificate.

          Just get a lich or some master dwarves or something, I'm sure one of them will make a computer golem for you.

          I assume that you've never worked in the HR department of a company that has had a disgruntled lich on the payroll.
      • "when it's just easier to fix the results after the fact?"

        Not if you're a dead 5th level Cleric.

  • how (Score:2, Funny)

    by Anonymous Coward
    "How to protect your electronic devices against lightnings. A research paper by Angus Ingrid, University of Technology Berlin".

    Here is an extract from the concluding part:

    "After carefull research we are now convinced that the solution to the problem was: roof."

  • Mitigation (Score:3, Informative)

    by jonadab ( 583620 ) on Tuesday May 11, 2004 @01:55PM (#9118739) Homepage Journal
    Prevention (of a lightning strike) is impossible, or at least too expensive to
    be practical. What you want is to minimize the amount of stuff (equipment,
    data, ...) that it destroys whenever it hits. For starters, you need to split
    your network into segements in such a way that data can travel between the
    segments but lightning won't. Wireless is one option, but I think there are
    other ways to accomplish this. Some UPSes have data line protection...

    Then there's data. One word: backups.

  • Fiber (Score:5, Insightful)

    by crow ( 16139 ) on Tuesday May 11, 2004 @01:57PM (#9118753) Homepage Journal
    People have suggested wireless, but another option that isn't an issue for power surges is fiber optic connections. You probably won't run them to each computer, but with some strategic placement, you can at least electronically isolate different portions of the network.

    That's a good idea regardless of lightning, simply because ground isn't quite the same from building to building. (Or sometimes even from outlet to outlet.)

    • Re:Fiber (Score:4, Insightful)

      by aaarrrgggh ( 9205 ) on Tuesday May 11, 2004 @02:26PM (#9119038)
      Fiber is the starting point. Lightning rods (ideally the dissipation kind that send a spark into the clouds) will reduce the likelihood and magnitude of any pulses, but fiber between buildings is essential.

      Once you are inside a building, there are so many paths for the lightning to take, it is unlikely that you can do anything quickly to fix it. Surge arrestors on incoming telephone, power, generator lines will help; multiple layers of protection (second set, finer grade) at the panelboards will filter out even more.

      If you don't do these things, have sacrificial components and spares. Usually that is easier...
      • >Lightning rods (ideally the dissipation kind that send a spark into the clouds)

        That type is controversial. Vendors and anecdotal evidence insist that they work. Competing vendors and physics-based calculations insist that they don't.

        >Once you are inside a building, there are so many paths for the lightning to take, it is unlikely that you can do anything quickly to fix it.

        Provide it a better path, outside the building. That would be a short, thick, *straight* run of copper to a good earth ground.
      • Here's one, tell me how you would fix that:

        College campus with approx 14 buildings, spread out over a distance from each other. All buildings are home run back to a central building which serves as the fiber aggregate.

        Lightning struck a tree, approx 30 feet from one building, approx 100 feet from another. The bolt spiraled down (nice bark pattern from where the bark got blown off, and the bark was smooth enough some of us used it wet as skates), dug into ground, and scattered all directions. The building

  • Lighting tips (Score:4, Informative)

    by n1ywb ( 555767 ) on Tuesday May 11, 2004 @01:59PM (#9118776) Homepage Journal
    Lighting is powerful stuff, it can travel through miles of air, which has a resistance that's probably in the teraohms. There's not much you can ever do in the event of a direct hit. But you can minimize the damage caused by lesser nearby strikes by using surge protected patch panels. Make sure they're connected to a good low resistance earth ground. I've seen them often in networking catalogs. Things like NICs and hubs will often act as a fuseable link, opening up or shorting to ground and preventing the damage from spreading very far.

    As a said, in a direct strike, you're pretty much screwed no matter what. Indirect strikes can induce very high voltages, since they give off a pretty good EMP. It's extra-important to surge-protect the long runs of cable. You don't need to lay new cable, just install surge protectors at both ends of the run.

    Buy cheap networking equipment, and keep money to replace it on hand.

    • Re:Lighting tips (Score:3, Interesting)

      by tzanger ( 1575 )

      We use substation-class arrestors to protect or industrial motion controls from direct strikes. Not cheap, you're right, but they do work.

      Something else to keep in mind is that unless you're talking about spark-gap or gas discharge type arrestors (i.e. anything like that will be SPECIFICALLY mentioned on the box), you're dealing with Metal Oxide Varistors (MOVs) and the protection should be REPLACED after every major storm since you cannot practically test if the MOVs will clamp properly again. The only

      • This is why consumer equipment with MOVs always has a breaker, not a fuse. If (when) the MOV fails short, hopefully the circuit is opened very rapidly.
    • Why guess? According to this page: http://hyperphysics.phy-astr.gsu.edu/hbase/electri c/lightning2.html#c4

      The current from lightning is about 10 kilo amps. The voltage is described as several hundred million volts. Let's say 500E6 volts.

      Ohms law E=IR, or R=E/I solving for R.

      R = 500E6 / 10000 = 50,000 ohms

      • Re:Lighting tips (Score:3, Informative)

        by n1ywb ( 555767 )
        Hahah! Common sense says that's WAY off! 50 k ohms from cloud to ground, if it was THAT low you could draw a spark gap between the leads on your OHMMETER!! Your 9v battery would kill itself in a minute from the current flowing between its terminals. To say NOTHING of the arcing that would occur in every electrical outlet in your house! You can't even measure the resistance of an air gap between two leads using your ohmmeter on the megaohm range. Common sense says that the resistance of air is so high that i
        • Common sense is anything but common it seems.

          You can't get around Ohm's law. I don't know about you, but around MY house, we obey the laws of nature.

          R = E/I. If there is no current flowing, the I is Zero, and R is undefined. If the air is ionized, then current is flowing, and R is 50K ohms.

          So to say what the resistance of air would be before the air is ionized and current is flowing is nonsensical. When you say teraohms or petaohms, I wonder how you got those numbers. And why those numbers, and not exaoh
          • Pre-lightning strike, we can probably think of the system as a giant air-dielectric capacitor. There is probably some amazingly tiny leakage current associated with the potential difference between ground and clouds. (drops of water, air currents, are going to ensure some charge gets moved => current flows)

            I agree though, the resistance is so high as to be nonsensical. After all, quality film caps already have resistance in the order of gigaohms, and the dielectric is some millionths of an inch thick.

          • Re:Lighting tips (Score:2, Informative)

            by B1 ( 86803 )
            Ohm's law really only applies to linear circuits and linear elements (e.g. conductors, resistors). It doesn't apply to insulators (i.e. air) or semiconductors, which have non-linear V/I behaviour.

            For an insulator such as air, you must look at its dielectric strength as well as the distance. From this, you can calculate the breakdown voltage required to generate an arc. For air, I believe it's roughly 10,000 V / inch. Of course, this depends on factors such as humidity, temperature, pressure, gas compos
    • Lighting tips
      Lighting is powerful stuff, it can travel through miles of air

      Thomas Edison was a Genius!! Lighting through air. So much better than lighting through wood.

      I recommend the new low-power LED lighting. It's expensive, but it's mega-awesome.

    • An interesting explanation about lightning can be found here. [howstuffworks.com]
    • >But you can minimize the damage caused by lesser nearby strikes by using surge protected patch panels. Make sure they're connected to a good low resistance earth ground.

      Good, good.

      Add one more vital point. There must be only one ground connection for all of the incoming wires. During a nearby or direct strike, two ground rods a few meters apart may temporarily be thousands of volts apart. If the surge protector for your phone is on one of those and the protector for the network is on another, well, bo
  • ...we're in the middle of a gigantic snowstorm. With thundersnow, yet, which is kind of unusual. I heard the forecast and thought "Hmmm, OK, a few flakes maybe!" (it was something like 24 C yesterday). Today? 10 cm of snow followed by a predicted 10mm of rain tonight, more of the same tomorrow. Looking outside my office window, I'm thinking we've had more than 10 cm already. It's been coming down so thick that driving visibility is severely curtailed.

    Still, it's kind of neat to have one of these storms in
    • I must be your neighbour... its a virtual whiteout here in Regina, SK.
      • Yeah, I'm in Winnipeg. Close enough for Canada. ;-)

        Just listened to CBC on the way home from work - we have about 20 cm on the ground now, another 20 by tomorrow. Branches all over the place, power out, TransCanada closed... crazy, man, crazy.

        Of course the farmers are loving it, and I can't blame them. About time we got some moisture into the ground. Lots of nitrogen, too. I can't complain. Besides, it gives me an excuse to stay in tonight and watch Calgary kick ass! ;-)

  • APC makes inexpensive products for this (Score:5, Informative)

    by toastyman ( 23954 ) <toasty@dragondata.com> on Tuesday May 11, 2004 @02:03PM (#9118824) Homepage
    Take a look at APC's rackmount "ProtectNet [apc.com]" stuff.

    A 1U rack mount chassis with 24 slots (you can protect up to 16 data lines) is $30. Then you can buy different plug-in modules for different devices. They have them for 10/100BaseT, regular Telco phone lines, T1/ISDN/etc, RS232, etc.

    Get one of these [apc.com] for $18 per Cat5 you want to protect.

    Keep in mind that nothing is going to protect against a direct lightning strike, but these are good filters for surges that can come from an indirect hit.

  • 10BASE5... new? (Score:3, Funny)

    by mrscott ( 548097 ) on Tuesday May 11, 2004 @02:16PM (#9118948)
    I know a lot of Slashdot readers are pretty young, but wow... 10BASE5 (thicknet) being new or unheard of... makes me feel OLD (and I'm only 30!)
    • i'm one of the young ones i assume (23) and i was setting up a thicknet network when my highschool replaced their aging macs with new whitebox pc's, and that was in..ooohhh 1995.

      not even 10 years ago, but i suppose in techterms that should be enough to me me feel old...

    • I don't understand why the poster thinks the readers would know 10baseT but not 10base5 considering they are both quite old wire types.

  • simple physics (Score:1, Funny)

    by Anonymous Coward
    ahh yes my friend you see it very simple really when you think about it. you could outsource to somewhere like Florida [myflorida.com] or Boston [bostonjobs.com].

    come on /. what's next on this goddamn forum?

    "excuse me but we in bangladesh were wondering if you could ever so kindly sho us how to do a hip replacement?
  • THE best way to avoid equipment damage during a lightning storm is to unplug your equipment. From mains and network. If your mains is lightning-safe, you could leave that on. Getting that many people to unplug units is practically an impossibility, I know, but crucial network nodes could be unplugged at the highest risk times. Factoring in some redundancy could be a good idea so if one router gets smoked, there is another somewhere else (geographically) to lower the odds of a complete system down.
  • Twenty years or so ago I read a USENET post, by a guy who had made a couple of long visits to India, He wrote how he knew he couldn't count on the Indian electrical grid providing clean power. So he brought a UPS with him. It lasted him a short amount of time. I don't remember the details as to whether he went through several North American UPSes.

    But he eventually bought a locally made UPS. He said it was noisy, making hissing and spitting noises. But it worked great.

    Well, that was twenty years a

  • Just pile human bodies over top of all the physical lines. They attract lightning and absorb all the damage. Besides, if Indians are willing to work under inhumane conditions in call centers for pennies an hour, they'd probably be willing to do this for a few cents more, right?

  • Grounding! not devices (Score:3, Insightful)

    by redelm ( 54142 ) on Tuesday May 11, 2004 @02:22PM (#9119013) Homepage
    There isn't some magic box that will make this problem go away. Actually, there is but you said you don't want new lines -- fiber!

    You can get arrestors for 10base2 and 10base5. These should be installed on every building, near the electrical service panel (entrance) and tied to the building electrical ground stake. I think you still have those with ring-mains. Use as short and as fat a wire as possible -- impedence matters.

    10baseT and 100baseTX should never be run inter-building and arrestors for it are hard to find. Beware the cute little cubes in userspace -- they have a long ground return path which presents high impedence, forcing more of the surge through active components.

    Make sure all your computers have three-prong plugs.

    • Much as I hate to say it, fiber isn't an end all solution. All it will protect is the networking gear from a network side strike. A near hit will induce EMP on any and all copper connected in any way to the machines, so the NIC might be fine, but the Routers, Hubs, UPS's, Switches, PC's, Servers, all connected to the power grid, or phone lines, etc, will become slag toast in a a very near or direct strike. Have geographicly seperated redundancy, and spares on hand.

      • Yes fiber is NOT an end-all solution, but using fiber will isolate network segments from lightning strikes. If a bolt hits a computer here, it doesn't fry a computer 10 miles away. Nonetheless, the original poster doesn't have the luxury of replacing all his copper with fiber.

        It's assumed that the equipment is connected to surge protectors on the power line; I believe the original poster was wanting to protect the network cabling from lightning strike.

        By far, the most important thing to do is grounding (o
        • Grounding is vital, but depends quite a lot on the power grid setup. Here in the US, specifically in Florida, the ground actually runs on the return on single phase AC power. In the panel box, the ground and phase return (cold) are on a bus connected to a ground in the earth. This means that a strike can travel either through equipment or through ground with similar ease to ground path.

          As for a lightning rod, you are quite correct that they need to be near the building being protected. Since the lightning

    • With interbuilding cables, only earth-ground one end of the shield. Earth potential can vary by several hundred volts between buildings, even without the storms. If you ground both ends, you are creating a dangerous high voltage ground loop.

      Fiber is definitly one of the best solutions for eliminating ground loops on inter-building runs.

  • How about using a copper-fiber ethernet bridge at the points where you want to isolate? I suppose the cost might be problematic, but it shouldn't be terribly difficult to find.

  • One Word.... (Score:2, Informative)

    by Lord_Rion ( 15642 ) *

    Fiber.... Get a two fiber to 10baseT, 10Base5, 10Basew2, 100BaseT or 1000BaseT transeivers. Lightining doesn't really impact fiber. Then use fiber for the long haul...

    OR

    you can buy 4 Fiber transeivers and a two, 1 meter fiber patch cords and put 2 transeivers on either end and use it kind of like a optical isolator. then if lightining hits the transport copper you, at most lose 2 transeivers, and the networks on either end are ok. Then all you should have to do is replace the 2 transeivers on either end.
    • Just don't plug the tranceivers into the same circuit as the rest of the equipment. Should be isolated there, too.
      • yeah.. I guess I should have mentioned that.

        You will need some form of circuit isolation for the powered transeivers on each end. A really good power bar.. or UPS will probably do it for you. And you should plug it into a completly different electrical circuit from the rest of your network, if you can.. :)
  • Whenever there is a lightning storm get some employees (aim for the expendable ones), to run around the outside of the building while carrying metal baseball bats, lengths of pipe, or wearing tinfoil body suits. I save thousands with this method and also avoind paying out those pesky unemployment benefits!

  • Re: (Score:2, Funny)

    by account_deleted ( 4530225 )
    Comment removed based on user account deletion
  • You can hope the lightning won't strike, but beyond that any commercial lightning protection available will not save any electronic equipment from a lightning strike. Lightning is just way too fast for the electronics in the circuit to respond... litterally the electronics get burned before it can even think about overcurrent. Maybe, if you are really, really lucky, just your power supplies burn out.
  • Every PC, every switch, every printer, every server.

    We installed 3 printers, 6 PC's, and 1 server at a client. The next day, the pole outside got hit by lighting. The electricty burned the CAT 5 in the walls and smoked all the PC's and printers. The server survived, all it needed was a new NIC.

    Insurance paid us to do the job all over again...
  • Tell your bosses to either learn about and purchase protection equipment, or don't and learn about lightning damage, then buy new equipment and THEN buy protection equipment.

    Arresters typically come with insurance; if the protection fails to protect, they pay you. If this fails to catch your PHBs's attention, start wearing a scuba diving outfit to work and tell them that the rubber is to prevent you from getting killed by the lightning, and oh, by the way, would they mind very much if you took out life ins
  • Fibre is a good failsafe method. Of course where not pratical you should consider surge arrestors.

    I once worked for a telcomms comapny which amongst other things made most of the surge arresotrs used in Italian exchanges.

    What I learned is that despite the fact that there are very many different solutions around, the simple and very effective solution uses a gas discharge device in paralell with a transorb (bi-directional zener). The transorb is very fast and has a high voltage, it briefly protects the l

  • Hopefully, you can't (Score:1, Insightful)

    by Anonymous Coward
    Then I can have my job back.

  • Gronding is key (Score:2, Informative)

    by zapster ( 39411 )
    I sell and install radio equipment that is installed on towers that range in height from 40 to 1400 feet. The taller ones are guarenteed to get direct hits from lightning ~every~ thunderstorm. The key to preventing damage is grounding. It doesn't matter what kind of lightning protection you have if your site grounding is not up to par. In a commercial building situation, the power entrance to the building must have adequate grounding. Isolation transformers are a great help as well. Lightning can also enter

  • 10Base5 was designed for running between buildings. If at all possible you should use fiber for that job, but if facing the choice of which segment to replace, get rid of all the 10Bast2 and 10(0)BaseT NOW.

    Ground loops are a far more likely problem than lightening, and only 10Base5 has any protection for that. (and then only if your transceivers are designed correctly...)

    Even still glass fiber is the only way to go. I'm just giving you a priority of replacing things.

  • I recently built a box and installed a home network down in Venice, FL that has been struck directly by lightning the previous summer.
    the lightning hit the electrical mains (the meter + main breaker on the exterior of the house), which happens to have the POTS POP 6 inches away.

    they had to replace nearly every electrical device in their house.

    At my own home, i recently discovered that I've been running 15A worth of computer equipment (boxes, monitors, net gear, etc) on an UNGROUNDED line. (house wiring ci
  • For my home network (and wired alarm system), I connected a 130V MOV (metal oxide varister) to each line. The other end of the MOV is connected to a 1 amp fuse. The other end of the fuse is connected to a good ground:

    ---Ethernet Lead 1 - MOV - 1A Fuse -\
    ---Ethernet Lead 2 - MOV - 1A Fuse --\
    ---Ethernet Lead 3 - MOV - 1A Fuse ---\
    ---Ethernet Lead 4 - MOV - 1A Fuse ----\
    ---Ethernet Lead 5 - MOV - 1A Fuse ----- Ground
    ---Ethernet Lead 6 - MOV - 1A Fuse ----/
    ---Ethernet Lead 7 - MOV - 1A Fuse --

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