Lightning Protection

Discussion in 'Hardware' started by hrothgar, May 2, 2008.

  1. hrothgar

    hrothgar Private E-2

    I live in a region prone to frequent violent thunderstorms. Many, including myself, have sustained damage to their computers during such events via telephone line connections. The protective device that I currently, which also incorporates a battery back-up power supply, successfully blocked a recent incident but now needs to be repaired as a consequence. It occurred to me that what might be a better idea is a small plastic fuse box equipped with input and output jacks. The easily replaceable and inexpensive fuse or fuses within would be of an amperage below that which could fry a modem or worse. No one seems to offer anything like this, however. Not being an electrical engineer am I overlooking something that would make this concept infeasible?
     
  2. lbmest

    lbmest MajorGeek

    I'm not an engineer either, but common sense would tell me that the over-voltage from a lightning strike would leak past a cheap fuse in the time it would take to burn it. We are talking milliseconds here and the fact that your surge protector needs repairing says that it did it's job in protecting your comp from a massive over-voltage.
    You get what you pay for.;)
     
  3. hrothgar

    hrothgar Private E-2

    You may be right. If someone could design a more practical phone line surge protection device, however, I'm sure that it would sell well. I'm not entirely sold on the current combinations due to the fact that they need to be repaired once used. Since it's usually only the phone line surge protection circuitry that gets fried, it would make more sense to offer separate devices for modem surge protection, perhaps in the form of disposable six packs. If the cost of each unit is less than your time plus gasoline it would seem to be a more economical way to go.
     
  4. dlb

    dlb MajorGeek

    Most of the better high-end surge protectors and UPS units have phone line protection plus they come up to $50,000 (or more) insurance policies where they pay to replace or repair any equipment that was damaged by a power spike that was plugged into the unit. These cost more but in areas with lots of lightning, it's probably worth it.
     
  5. studiot

    studiot MajorGeek

    Is there something about Americans, from Franklin onwards, that makes them want to glow in dark?

    Disconnect your equipment during lightning storms. Especially disconnect the ground connection - It is normally the ground return flash that causes the damage, not only to IT equipment but to TV, alarms and other electronics.

    We get regular repair business in the SW of the UK from lightning damage as well.
     
  6. maybeok

    maybeok Private First Class

    Hi "hrothgar" = Re: Lightning Protection

    Noticed your request for information re "Lightning"

    I live in Australia and about a month ago purchased a "Belkin Surge Protector" the one in a green coloured box for $69.95 AUD! Other dearer units were available?

    This unit gives plus all you would require for protection!
    Also it gives 4 power outets with Phone/Fax/Modem protection
    If you go to purchase one make sure you look on the box for " Essential protection and insurance against electrical surges - even lightning"

    Be sue the list the words " - even lightning" as I have noticed at some store the boxes do not list the "- even lightning". Keep the box in case you do require "Insurance" that they offer as from memory the brochure inside does not list" - even lightning"
     
  7. Fred_G

    Fred_G Heat packin' geek

    Heck yeah studiot, I have my router on a UPS... Can't lose pron, I mean interweb...:D

    E
     
  8. hrothgar

    hrothgar Private E-2

    I use a product similar to the Belkin Surge Protector. In fact, I'm on my second one due to the fact that the rechargeable battery in the first one died for some reason. My point, however, was that once such units encounter a lightning strike the phone line surge protection component within the unit will probably get fried in the process of saving your modem. That seems to be their only flaw. One is left with no other option other than to return the it to the dealer for repair. It would therefore make more sense to use separate smaller, less expensive, and perhaps disposable devices for modem protection given the currently high cost of gasoline and a couple hours of your time.
     
  9. hrothgar

    hrothgar Private E-2

    By the way studiot, we Yanks are way too lazy and clueless to ever consider disconnecting electrical equipment at the onset of a thunderstorm. Actually, storms in the central states can develop suddenly and unexpectedly during the warmer months and they can also be quite violent. A nearby town was nearly wiped out by a tornado five or six years ago. I would seriously consider moving to Australia but I've heard that it abounds with highly venomous creatures.
     
  10. ItsWendy

    ItsWendy MajorGeek

    Actually a fuse just won't work, nor will a breaker. The problem is lightning is fast, and if it does actually vaporize the fuse it will use the vapor as a circuit path. You can't win, you can't break even.

    Surge suppressor equipment works by shorting the lines in the event of really, really high voltage. The components that do this are also fast (lightning still wins a lot of the time). The usual component is a MOV. A lot of surge suppressors have an indicator to show they are still functional, this is because they sacrifice themselves in the event of a lightning strike as a last ditch line of defense, and then will never work again.

    There are no cheap solutions other than unplugging the electronics in question. Personally I would spend over 30 minutes going through my house and unplugging everything, if I was so inclined. I was lucky (dumb luck in this case) and the wiring leading to my house is all underground, for many miles. I can still get bit, but it is a lot harder to do serious damage because of all my neighbors (a dense neighborhood at that) which gives my surge suppressors a better chance of working and surviving a strike. The only lightning damage I've ever suffered was my garage door opener, which didn't have a supressor at the time. It did after that though.
     
  11. ItsWendy

    ItsWendy MajorGeek

    Battery? You're not talking a UPS are you? If you are the batteries have a limitied life (several years) and are replacable. I'm trying to figure out how a surge supressor would use a battery?
     
  12. Fred_G

    Fred_G Heat packin' geek

    Most UPS are combination backup power and surge protectors. The batteries do die after a while though. I buy new batteries to keep my 'puters happy.

    I seem to remember something on the interweb about a device that could be installed where the power enters a building and it would act as a surge protector, can't find it though. Need more coffee...:zzz

    E
     
  13. Jerkyking

    Jerkyking Sergeant Major

    I agree with Bill and Studiot. I think your safest option would be to disconnect everything.

    You should also check with your insurace company. I have my electronics covered against such damage for only $8 a year, a deductable still applies but at half the price of a PC I went for it.
     
  14. studiot

    studiot MajorGeek

  15. hrothgar

    hrothgar Private E-2

    OK, here is a partial solution I came up with. I wired in a small rocker switch to physically disconnect the phone line when the computer isn't being used. It's far more convenient than unplugging and replugging. The same thing could, of course, be done with the 120V power chord. If you happen to be handy with tools, both switches could be mounted side by side in a small wooden box that sits next to the mouse pad.

    Radio Shack offers a wide variety of rocker, toggle, and slide switches. My choice is the illuminated type since they are a more fool proof indication of circuit status. Perhaps someone with more knowledge than me and catalog handy could offer parts numbers for the best choices.

    By the way, maybeok hasn't commented for a while. I hope that he (or she) hasn't been bitten or stung by some toxic creature. I suppose that it's a common practice for Australians to keep a large assortment of anti-venoms next to the Foster's beer in the frig.
     
  16. ItsWendy

    ItsWendy MajorGeek

    Good luck. You know your area best, just be aware, lightning jumps gaps, big ones, and a rocker switch uses about 1/8 to 1/4" gaps. You might think about putting a surge suppressor after the rocker switch, just in case. If nothing else for when you're not there to pull the plugs.
     
  17. hrothgar

    hrothgar Private E-2

    Bill - good advice. RadioShack switches probably won't provide a sufficient gap. Unless I can find an off-the-shelf switch that will work I'm afraid it's "back to the drawing boards". In the event that I do I'll post a few CAD generated JPG drawings of the "small box conveniently located by mouse pad" including its parts list and wiring diagram.

    Needless to say, your advice about still using a surge suppressor should be heeded. For one thing, individuals could easily forget to push or flip the two switches to the "off" position after using their computers.
     
  18. studiot

    studiot MajorGeek

    Remember when designing your disconnection device that the normal single pole on/off switch is sourced for cheapness at 120 volts not protection against half a million volts.
    Them old double or treble throw-over knife switches from frankinstein movies are best.

    Remember also that a nearby lightning strike can locally disturb the ground conditions long enough to take out any sensitive grounded equipment. That is when the strike occurs it locally raises the ground potential several hundred or thousand volts for a few milliseconds.
    I have seen ISDN equipment blown off the wall by this means along with a 60" television, pc equipment etc. Their only common connection was the ground.
     
  19. hrothgar

    hrothgar Private E-2

    Thanks, believe it or not I did briefly consider a knife switch because of its generous gap but then dismissed the idea due to size considerations. If I understand you correctly, the switch should also disconnect neutral and ground at the same time because lightning doesn't play by our rule book. Most of the spikes here seem to enter via telephone lines using two wires. I suppose that both of them would also have to be widely disconnected.

    Yep, it looks more and more like I'll have to hire someone named Igor to find parts. There is an old barn and a couple of old sheds on this property dating as far back as 1913. I've noticed that they have knife switches mounted on the walls. Unfortunately, they are almost as large as the box that I had in mind. Igor would probably like their rusty cobweb infested look, however.
     
  20. hrothgar

    hrothgar Private E-2

    Thanks for everyone's input. Allow me to boil everything down to the key points.

    1. Disconnection is the best protection from lightning surges
    2. If a switch is used (and idea that I proposed) the gap would have to be large enough to eliminate the possibility of spark breaching that gap.
    3. Knife switches would therefore be most suitable for the job.

    I've attached a JPEG image of a CAD generated drawing. The base of the "Disconnect Box" would require less surface are than a mouse pad. The box would house two DPST (double pole single throw) switches to handle both power and phone line connections. Due to time constraints I haven't included either a wiring diagram or the input/output hardware that would be fitted to the flat surface on the back of the box. If anyone thinks the concept is viable I will attempt a more detailed drawing.

    There is one small problem, however. At the present time I haven't been able to locate suitable knife switches. They are all either heavy duty industrial types or toys for classroom science demonstrations. I'll keep searching.
     

    Attached Files:

  21. studiot

    studiot MajorGeek

    You might like to look into an older protection device called a spark gap arrestor.
    these lend themselves to DIY and are self healing.

    Two small flat blocks of carbon are held in mechanical contact but the mating faces are insulated by a varnish coating. The separation is of the order of 4thou (.004 inch)

    In each pair one block is earthed and one block is connected to the protected line at the entrance to the building.
     
  22. hrothgar

    hrothgar Private E-2

    Thanks studiot, but the dozen or so Yank brain cells that I have dedicated to electrical theory probably wouldn't be sufficient to grasp the concept.

    As far as the previously illustrated connect-disconnect box is concerned, it could conceivably be practical if mass produced using two pieces of injection molded plastic for the housing and sold for $20 dollars U.S. or less. Although an average person probably couldn't afford the set-up/fabrication costs, a company with manufacturing ties to China could. I don't see any reason for the size of the contraption to exceed 5"X5"X5". Perhaps the addition of a couple of L.E.D.'s would give it a more hi-tech look.
     
    Last edited: May 10, 2008
  23. hrothgar

    hrothgar Private E-2

    Thanks studiot, but the dozen or so Yank brain cells that I have dedicated to electrical theory probably wouldn't be sufficient to grasp the concept.

    As far as the previously illustrated connect-disconnect box is concerned, it could conceivably be practical if mass produced using two pieces of injection molded plastic for the housing and sold for $20 dollars U.S. or less. Although an average person probably couldn't afford the set-up/fabrication costs, a company with manufacturing ties to China could. I don't see any reason for the size of the contraption to exceed 5"X5"X5". Perhaps the addition of a couple of L.E.D.'s would give it more of hi-tech look.
     
  24. hrothgar

    hrothgar Private E-2

    greysunrise, your post, if you made one, doesn't appear to be here for some reason but I did receive your ideas through a MajorGeeks email. I'm glad to see this thread is still drawing some attention. I once contacted a company about the knife-blade switch idea but their response was something like, "everyone reaches behind the computer and disconnects the phone line during an electrical storm so it isn't necessary." My response was, "Oh. really? What if they are sleeping or away from home?"
     

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