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Protecting Computers From Lightning?
rackrent writes: "I'm wondering what others do, both in their workplaces and homes to protect from lightning strikes. One look at Intellicast's lightning page should make us aware how often this must affect computers. Again, just curious as to what everyone does to safeguard their machines against lightning."
there is only one 100% solution: redunand computing centers in a different solar system. You can get close though if you redunand center is on a different continent.
Be sure to check the size of your box. CDs do _not_ fit easily in our box, because of a lip on the top of the box. If that is a problem, you may want to hunt down the smaller size CD-Rs (80mm?) and use those for backups. Not as capacious (and more expensive), but presumably your porn video collection isn't your most important data.
Ooh, a sarcasm detector. Oh, that's a real useful invention.
Also with underground lines, even though there are backhoes and tree roots that will take them out on occasion, you don't get huge areas with lost power during bad weather (unless the substations go). So they should be able to get a crew out quickly and get your service back.
As for trees growing deformed, that's nothing compared to the hacking that power company saws do to the trees to try and minimize the risk of branches taking out the lines.
I have buried lines in my neighborhood and I love them.
Ooh, a sarcasm detector. Oh, that's a real useful invention.
I was thinking how to get a rocket to spool a lenght of wire at the end without breaking or melting away. Try a length of tungsten wire or rod (about 3 or 4 feet) near the rocket's engine if the copper wire melts due to the heat from propulsion. The rest of the copper wire can pour off the bobbin with the end taken off toward the ground.
Once the lightning ionizes the trail, all hell should light up...
Be sure to check the size of your box. CDs do _not_ fit easily in our box, because of a lip on the top of the box.
Those small disks max out around 150MB. That's too small....
Hrm, sounds like a cheap, fast and easy way to protect stuff and sounds plausible. Anyone else heard of this?
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Bear in mind that any such thing that you build yourself won't be UL listed and if you start a fire with it your homeowners insurance might not pay out because of that.
I see even classic Slashdot is now pretty much unusable on dial up anymore.
See alyandon's explanation immediately above for an excellent explanation of why overhand knots in the power cord work. I commend it to the attention of moderators as well. It is an excellent example of the type of comment that positive mod points are designed for.
See Mark Minasi's "The Complete PC Upgrade & Maintenance Guide" (9th edition = ISBN 0-7821-2357-0, published by Sybex) for one example of a book containing that technique.
I see even classic Slashdot is now pretty much unusable on dial up anymore.
The faster the change in the level of current, the greater the opposition of the induced EMF in the original conductor. This opposition, called inductive reactance, increases as frequency increases.
Any time a wire is looped back on itself, whether as a turn in a transformer coil, or a knot in a power cord (remember, the "hot" and "neutral" lines are connected to each other through the load and through the source, and the same current that flows down one flows back up the other, they're part of the same series circuit), or as a twist in unshielded twisted pair (again, both conductors are part of the same circuit), the inductance is greatly increased over what it would be without any "looping", because the proximity of different parts of the same conductor to each other intensifies and reinforces the magnetic field.
The power surge that tends to burn out equipment isn't the original lighting bolt, it's EMF induced in the electrical lines by the lightning. This induced "spike" tends to have an almost instantaneous rise-time. Therefore it can be considered a very high frequency current. An inductance (coil, loop, twist, knot, etc.) with negligible reactance at 60 Hz is going to have a very high reactance, or opposition, to that spike's much higher frequency. Most of the spike's energy is going to be used up in trying to shove current through that high reactance knot. The voltage drop across it, the difference in potential, is going to be most of the total voltage of the spike. Most of the total energy in the spike is applied to the knot. This high voltage will probably cause enough current flow in the knot to burn up the insulation and possibly partially melt the wire itself. If that spike didn't drop off as fast as it rose then eventually it would force a destructive current through every path it could find, knot or no knot, but fortunately individual lightning strikes end as quickly as they start.
I see even classic Slashdot is now pretty much unusable on dial up anymore.
Wire guided anti-tank missiles use a similar system. There is bobbin of wire on the back end of the missile. The ends of the wires are connected to the guidance electronics. The wire peels off the back of the bobbin as the missile goes down range.
Mea navis aericumbens anguillis abundat
I run a paranoid power system. Everything goes through the sacrificial surge protector. After that is the TripLite line conditioner. Then there is a UPS for each computer. Computers are either directly pluged into the UPS or have a surge supressor between them and the UPS. The phone line for the DSL has it's own surge supressor too. After my appartment building was hit I didn't have to replace any of my electronics, but I did replace the sacrificial surge supressor and line conditioner. Other people in the building were replacing everthing.
For the record, underground utilities actually have more problems with lightning. When lightning strikes a spot, it goes through the ground for some distance. As such it usually finds the underground wiring.
When storm clouds are brewing overhead and lightning is striking all around you, how's about turning off and unplugging your computer from every place it connects to the wall? No process is worth so much that its clock cycles are more important than the thousands of dollars you've invested in your computer[s].
Cheers,
levine
Also put in a surge suppressor on your circuit breaker panel. A whole-house suppressor is slower than the type used on a power strip, but can handle much more power. This will divert large surges, and is actually to protect the smaller surge protectors.
Finally, use the power-strip style surge protectors. These are delicate fast-acting suppresors which can protect your devices from minor surges.
Here is a description of this multilevel protection.
APC has something like a $25,000 guarantee for power surges. I personally have seen an APC surge protector melted to a puddle of goo, and the equipment plugged into it was just fine after a new power cord. (The end melted into the surge protector.) I am absolutely sure that the $50 more you spend on a good surge protector is worth every penny. APC also makes UPS units with the same capability (as far as surge protection), as well as other line protectors such as CAT5, phone, and COAX. Protect every line going into your datacenter and if anthing gets hit by lightning, APC will write you a check to repair the equipment. See their site for the details.
LOAD "SIG",8,1
LOADING...
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RUN
My family's computers survived a direct strike with nothing more than your average $15 surge protectors. What do I mean by direct? The lightning hit the power pole 20 feet from my house and blew up the transformer.
The only equipment to get fried was stuff connected directly to telephone lines (modem, answering machine, phone, fax).
For the average user, a $15 power strip/surge protector is probably enough. For the paranoid, get something with a replacement warranty. It may not work any better, but at least you'll get a new computer if you do get hit by lightning (and the magic smoke is released).
Aside: Isn't it odd that there is no obvious attempt to market optical-cable connections for e.g. modems, to eliminate the surge issue? What would this be? Just a very short length of fiber with a cheap led at each end to convert from the electrical signal to the fiber? I'd buy one. Go forth and find ye' a bakcer.
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Am I the only one who thinks Microsoft is a misnomer? Perhaps Macrosoft would be a better fit?
For the paranoid. We have one of their systems in our house. It'll take most anything that comes through the power line and re-nice it. Hell, I doubt I even need to use surge protectors anymore, but like I said, only paranoid people like me buy this stuff.
Well, thinking as an 'anarchist' might, I would simply swap a 240 VAC line for a high-powered laser if they switched to an optical connection. Voltage spikes are to be expected, but who's going to protect from an optical burst? :-)
For the home/small business network, Home depot does sell a unit as described above and it took about 15 minutes to install. It will absorb the hit, however your house will pass some of it along the circuits. I believe they are really designed to stop a fire more than anything else.
You will be a happy camper if you then have a surge protector too. This should stop all but a direct hit on your house. The power coming in is like a magnet I'm told. If you are going to get hit it will almost certainly be on or around where the power comes into the house. (I am not an electrician...)
Okay, we got the power covered, goodjobbob told you not to forget the modem, easy to do, but many of the surge suppressors have a built in line protector. However, remember that Cable/DSL modem too. You probably accepted responsibility for it when you got it from your broadband supplier. Have a UPS? Front end it with a protector. Even though it has one built in, the UPS is much more expensive than the protector is, so save it from itself.
My approach is that if it in any way, shape or form enters equipment from outside the house I put a protector on it. That would include your stereo, TVs, DVD player, VCRs, regular phone (the 2+ghz one that set you back $100) all that fun. I try to buy names I recognize and that can be screwed into places. This lets me hide a protector on the back of the stereo cabinet, etc.
Next check out the insurance policy. Why after putting all this in do you need to worry? Sorry but a direct hit is coming in, jumping through most everything and ruining your day. That is also why, in severe thunderstorms, if possible I unplug the computers and the phone lines.
Life's not fair, but it beats the alternative...
This is what I tell most of our customers when they ask about lightning: "If your antenna is directly hit you're pretty much screwed". (Acutally this might be a good place for an appropriate goatse.cx link to illustrate how badly screwed).
I then go on to say that 99.9% of the damage is actually not caused by a direct hit. In fact, the purpose of most "lightning arrestors" is really to drain/discharge the static an antenna picks up.
This also applies to Power/Phone/Satellite TV, etc. etc. etc.. If lightning hits the pole outside your house, you probably will loose equipment. My personal experience is that even if the stuff doesn't immediately fail, you will have ongoing problems with anything exposed to that level of problem. Yes I've seen it.
That said, you can protect yourself in most less extreme cases. Unplugging EVERYTHING is always the best option but in reality isn't really an option for most people. The path I take is to go buy the best surge suppressor and/or ups that you can find. I personally prefer APC's. Most, if not All APC units include an equipment replacement guarantee so if you do take a direct hit you're covered. Remember to supress EVERYTHING. The power line, the phone cord, the satellite antenna cable plugged into the satellite receiver attached to the same power strip, etc. etc. etc. Lan surge supressors are highly recommended, especially if you go anywhere near outside with the cables, or to a "non protected" hub or similar.
Generally for the protection warranty to be effective you must make sure everything is protected or the warranty is void.
Hmmm.. I'm sure there's something else I wanted to add, but I'm not sure what, so I guess I'll quit rambling :)
And remember, off-site backup is always a great idea...
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First, there's the business vs. technical solution: The business solution is to make sure it has a surge suppressor with an adequate warranty, and that at any moment adequate backups of everything are offsite AND offline AND redundant.
Let's assume that's not good enough, and you're developing hardware you can't buy again. The obvious answer is to unplug it when there's a storm - including any networking or modem lines. But let's assume you have to stay online if possible.
Get a heavy duty surge suppressor - I got one from intermatic http://www.intermatic.com/comind.htm#3 for around 100USD (installed, actually, but at the same time I was having my service upgraded) I had a long talk with a senior developer there - they aren't warrantied against lightning; they're not in the warranty business. But they've saved equipment from lightning in the past.
Then get something for all your critical systems: Small cheap surge supressors are really designed to save your computer from the surges caused by your AC (or any other dirty device) and nothing as powerful as lightning. OTOH, if you're lucky it'll melt into a puddle when the lightning hits - and do it fast enough to save everything downstream. But they're better than not having them. Good ones are better. UPS Power Conditioners are better. (see also insurance, above)
I like the coil idea, although I can't guarantee it'd work, I think it'd be worth it.
Make sure your grounding is good - strong connections.
In general, btw, I prefer to keep electronics on separate circuits from anything else (esp motors, like AC, refridgerators) I don't think this would help in a lightning storm, but it cuts down on line noise.
I guess that's it. Good luck.
Looking for freelance Actionscript (Flash/Flex) or ColdFusion work and/or freelance developers. Email me, put Slashdot
I forgot all about the phone line protection actually. I don't use it, becuase on the surge suppressors that I have owned, the telephone protector gives out some sort of EMF that interferes with my radios. (Motorola two-ways and AM radio)
I would say that having using the coax protection is probaly not worth the extra money for the surge strip. (The ones i've seen are like $50-75)
Conformity is the jailer of freedom and enemy of growth. -JFK
1. Backups to tape/cd
2. Insurance - rental insurance is cheap and homeowners insurance is a necessity. Most insurance companies will cover such damage.
If your house gets stuck by lightning, and your house doesn't have a lightning rod or grounded antenna, most of the electronics in your home will be utterly destroyed. If your house or power pole gets hit by lightning, the current will arc across the blown fuse of a surge protector anyway.
Conformity is the jailer of freedom and enemy of growth. -JFK
I know all slashdot readers are electrical engineers in their spare time, but:
If you install additional grounds (for computers or whatever) the must all be bonded together. Bonding involves runing a piece of heavy copper (10+ guage) between all grounds. Different parts of the grounding system (Water pipe, copper ground rod, building steel etc.) have different potentials (sometime several volts or more). Without a proper bond, grounds in network cables can (and will) carry the load.
My wife worked for a local government that had a network bridged between to sections of a building. A construction error cut the bonding wire. The current flowing between the grounds on the network cables caught several computers on fire. Their unique system of troubleshooting (plugging in computers and waiting for them to smolder) is another story.
Anyway, bond those grounds. If someone tells you that you should have an Isolated Ground (a very bad idea) know that they are spouting BS. It only takes one link to equalize the potentials, your choice a 24 gauge network cable (and your computers innards) or a nice piece of 10 guage copper(or larger)
âoeWho knew something as harmless as willful ignorance could end up having real consequences?â
Actually, it sounds like the building grounds we not/not adaquatly bonded and the path of least resistance was the grounds in the serial/network cables.
âoeWho knew something as harmless as willful ignorance could end up having real consequences?â
Many Hams use products from PolyPhaser http://www.polyphaser.com/ that are designed to handle a direct strike. They also have information on "What is Lightning?"
Also, the ARRL has the ARRL Handbook, which has information on Lightning and protection as well.
Lastly, Don't forget that the Telephone line is a very common way for the lightning to enter your equipment.
What do I do in known lightning storms, besides the PolyPhaser protection? I disconnect my antennas and place the ends in a ceramic jar (Just in case).
But seriously, As an added precaution (and in keeping with the DIY spirit of most Ask Slashdot questions), I saw a really clever surge suppressor design. I can't find the original to credit it, but it's very simple: Just some bidirectional large zeners (with appropriate holdoff voltage) in a replacement 3 prong plug, inside the cap with no cord attached. Portable surge suppression, and IIRC, zeners are right around the correct frequency response for lightning, and usually large enough to sustain a smaller hit. $3 of components makes your $2 surge suppressor a $25 surge suppressor!
+5:offtopic,but anti-American
Yes, most transient protection zeners just call them 'bidirectional.' You get the same zenering voltage in either polarity.
Bear in mind that any such thing that you build yourself won't be UL listed and if you start a fire with it your homeowners insurance might not pay out because of that.
Good warning. IANAL, and all that.
+5:offtopic,but anti-American
IANAEE, but I can vouch for the importance of this. A company I contracted with had underpaid and incompetent monkeys wire their building, and the monkeys forgot this step. A few months down the road, EVERY single UPS connected to that circuit was fried in an instant. Luckily for them, they had every single PC plugged into a UPS, so no PC's were damaged. The 40 or so UPS's weren't so lucky, however. (You can take that as a vote of confidence for APC UPS's as well....)
I've got a cable modem. If some anarchist down the street 'accidentally' manages to jam his cable connection into a 240 VAC socket at his house, what's going to happen? Do ISPs have gear to protect against anarchists and such? Or would every computer on the street suddenly go up in flames? I'd like to think that people thought of this way before me, but I can't help but wonder. (Perhaps this is reason enough to get an optical Internet connection? ;) )
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suwain_2
Why don't you go back and study some more until you're able to explain exactly what an overhand knot does that is helpful, and how it works.
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Scientists restrict study to entire physical universe; creationist
But it's worse than that! The line cord consists of at least two and usually three conductors in parallel. Winding the cord into a circle only protects against common-mode transients; if you have a large surge which places the power-supply hot conductor at 900 volts WRT the neutral and ground (which are connected together at your main panel), your overhand knot will not protect you at all. The current surge will go through the coil one way through the hot conductor, fry your gear, then exit back through the other conductor(s); the net current through the coil is zero, so the protection against differential-mode surges is also zero.
And you know this how? (Exactly how do you get an "almost instantaneous rise time" in a current going through a path several miles long? There's this little thing known as speed of light delay, plus inductance in the plasma which carries the bolt itself...)Just from simple V=IR calculations it's easy to show that a 50,000 amp lightning bolt striking near a transformer where the ground has a 0.01 resistance will displace the ground voltage from "earth" by 500 volts. This will displace both neutral and hot at the transformer if it is grounded. Neutral will be re-referenced to ground at your service panel, but hot won't be; this allows the voltage surge to come in over the hot lead. Voila, hundreds or thousands of volts at your power supply. This is what lightning arresters and surge suppressors are for: to clamp the voltage, dumping the current to ground and dissipating the excess in IR losses in the conductor upstream (the conductor is a lot heavier and able to take punishment than your equipment probably is). Ferroresonant transformers (Solas and such) do a pretty nice job of regulating voltage excursions and eating spikes, but they do this with large hunks of iron and variable-saturation tricks. One-turn knots in line cords? Don't make me laugh. It didn't take me very long looking on the web before I found specific recommendations against knotting electrical cords.
Now go away or I shall have to taunt you again.
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Scientists restrict study to entire physical universe; creationist
I like this page better for lightning, its map is always up.
I came home once to find that my sister had plugged her surge protector into yet another surge protector, I loved it. Just an idea. I don't think it will do anything, I just got a kick out of it.
spacefem.com
This might be a little off topic, but just as important to consider is power quality also, which includes proper grounding, as mentioned in an earlier post. An UPS can take care of a lot of these problems, but if you have poor power quality, it is very taxing on your UPS. There's a few easy checks you can do with a multi-meter and the outlet you plug your computer into. You can do these checks both with your computer on and off, just use one of the other sockets in the outlets or power strip.
(Sorry, only applies to US, if anyone else wants to add on for European and other international standards feel free) 1) check your hot to neutral voltage: set your multimeter to Voltage AC and make sure the probes are plugged in for voltage, not current, measurement, consult your meter's manual. Put the red probe in the smaller outlet slit (the hot) and the black in the larger slit (the neutral) (although it really doesn't matter which one, its AC) You should read some where around 120volts +/- up to 2%, any more or less and you might want to check with your electrician.
2)check ground connection: Although this doesn't help with checking the current capacity of your ground, it at least is a decent check to see if its connected. Keep the red probe where it is (in the hot) and move the black probe to the ground hole (semicircular shaped), You should get about the same reading you got for step one, usual a little higher especially if there is a lot of current on the neutral. If you don't, make sure you have the red probe in the hot, try the red probe in the larger slit just to make sure. (your hot and neutral may be reversed, although this is pretty rare)
3)check your neutral to ground voltage: which if you do the math from steps one and two you can figure out. Put the red probe in the larger slit and leave the black in the ground. This reading is usually in the tenths of volts if anything. If it is much higher, and your step one reading is not in range, then you may have an over-loaded, or poorly supplied circuit. (i.e. you have to much current current on the netural, or a highly resistive neutral, or a low volate on the hot)
I hope that helps, an even easier way to check that just your hot, neutral, and ground are connected properly is to get one of those outlet testers at your local hardware store. And as long as you don't touch the probes together, or to yourself, when they are in the outlet, you should be safe, but if you are unsure read the multi-meter manual or use the outlet tester...Here's a decent intro to power quality issues, they mention stuff about switching power supplies, like those found in computers and other interesting topics on power quality...
"Karma can only be portioned out by the cosmos." -Homer Simpson