Slashdot Mirror
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?"
During monsoon season, outsource your IT operations to the United States.
-- We live in a world where lemonade is artificial and soap has real lemon.
Sure your bandwidth is lower (in general), but you can't induce a current along a 2.5GHz wireless link...
--
"we live in a post-ideological world..." - Billy Bragg.
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.
This space intentionally left blank.
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.
IIRC Protection from Lightning is a 4th level Cleric spell!
Geeks these days...
I watched C-beams glitter in the dark near the Tannhauser gate.
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.)
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]: