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How to Protect a Network Against Lightning?

Posted by Cliff on 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?"

4 of 120 comments (clear)

  1. Fiber by crow · · Score: 4, Insightful

    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.)

    1. Re:Fiber by aaarrrgggh · · Score: 3, Insightful

      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...

  2. Grounding! not devices by redelm · · Score: 2, Insightful
    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.

  3. Hopefully, you can't by Anonymous Coward · · Score: 1, Insightful

    Then I can have my job back.