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How to Protect a Network Against Lightning?
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?"
Two words, lightning rod.
Sure your bandwidth is lower (in general), but you can't induce a current along a 2.5GHz wireless link...
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"we live in a post-ideological world..." - Billy Bragg.
Prevention (of a lightning strike) is impossible, or at least too expensive to ...) that it destroys whenever it hits. For starters, you need to split
be practical. What you want is to minimize the amount of stuff (equipment,
data,
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.
Cut that out, or I will ship you to Norilsk in a box.
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.
-73, de n1ywb
www.n1ywb.com
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 one thing you do have to watch out for and that's long wire runs, be it power, or ethernet. Put inductors around the power lines, and minimize the runs. And yes I recommend a lightening rod as a part of containment. They aren't expensive, and an individual can easily install them. And last make certain you have a backup plan when something gets through, because it will sooner or later, despite your best efforts.
Take a look at APC's rackmount "ProtectNet" 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 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.
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]: