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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...
--
"we live in a post-ideological world..." - Billy Bragg.
" 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!
"Derp de derp."
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.
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.
--Ted
--Hired Net Grunt
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
"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 because of the point at the end, not the fact that they're rods.
poster three
"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."
One problem with your statement. Most natural phenomenon doesn't broadcast in the Gigahertz range. Two there are ways of dealing with unintentional interference (lightening or otherwise).
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]: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 (or "earthing" if you're in the UK). Have the chassis of your equipment connect to a good earth ground. Have the shield of your cable connect to a good earth ground. And by all means, make sure your surge suppressor is plugged into a good earth ground!
The purpose of the ground is twofold: 1) drains the buildup of static electric charge; and 2) provides a path of least resistance to ground (instead of through your sensitive equimpent) in the event of a direct lightning strike or a short to powerline.
The purpose of a lightning rod is not necessarily to "attract" lightning, but to drain the electric charge from the air. You want your lightning rod NEAR the equipment or structure you are trying to protect. To place it far away expecting it to "attract" lightning will leave you disappointed. Occasionally lightning DOES hit a rod; in this case, had the rod NOT been there, it would have hit the equipment it was placed to protect.
I've seen it over and over and over again, a surge protection device that's connected to an outlet without a ground prong. Let me say it in big, bold letters so it gets into your skull: AN UNGROUNDED SURGE PROTECTOR IS NO PROTECTION AT ALL. It's a bit like a condom with a hole in it. When the surge comes, it blows up all over the place.
Give me my freedom, and I'll take care of my own security, thank you.
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 buildings via phone and network cables so make sure the telco demarc is properly grounded.
:)
When I say properly grounded I mean #2 wire or better not a piece of cat 5 with all the wires stripped back and twisted together. The telco ground, the power ground and any other grounds must be tied together to prevent ground loops.
Get a master electrician that knows what he is doing to advise you.
On the rf gear I work on I like tripp-lite and polyphasor for protection.
I have seen the tripp-lite IB4 or isotel take such a huge hit that the rocker switch was blown completely across the room and the components inside were reduced to crumbly black bits that fell out the switch hole. I replaced it with another of the same unit and the equipment came right up. Then I gave it back to my salesman for a refund since they have a lifetime warranty!
Anyway spend the money protecting the entrance points from lightning damage. If you are protecting commercial buildings rather than individual computers then get high quality protection systems that give an indication when the protection fails.
It is important to remember that ground rods corrode away and have to be replaced. That lightning protection devices are only good for a couple of light hits or one big one. Then they must be replaced since they don't offer any protection anymore, though they still happily let power through. Lightning protection is a consumable not a one time purchase.
Grounding is primary, protection devices follow.
If you have serious problems, Motorola produces a manual called "R56". Do a site to R56 standards and you will be good to go though you won't have much money left