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Is it safe to use computer during lightning/thunder storm?

Discussion in 'Electronic Basics' started by nospam256K, Sep 21, 2004.

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  1. I can take up one more point. The ideas you express above are simply
    wrong, there is no scientific basis for that.

    In fact, it is often a component close to the input connection which
    fails, because the charge that comes rolling down the wire uses the first
    possibility to unload itself to a potential closer to earth level.
  2. Ron Reaugh

    Ron Reaugh Guest

    Clueless. This wacko has been stalkin large numbers of NGs for many years
    spreading this garbage.

    A well know fact is that good surge protection of electronic equipment has
    little to do with the earth ground. Just ask yourself how things are
    protected on an in-flight airplane. That technology is what is involved in
    good protection. When you are on the ground then providing a safe place for
    that lightning bolt to find earth ground is a real good idea for safety
    reasons but that has little to do with protecting electronic equipment like
    computers. Protecting such equpiment depends entirely upon shunting any
    overvoltages to common mode and the chassis.
  3. P.T. Breuer

    P.T. Breuer Guest

    Mmm. Very reasonable. Good explanation.
  4. Ron Reaugh

    Ron Reaugh Guest

    You see there really are people around who understand surge protection.
  5. w_tom

    w_tom Guest

    Electricity flows like an ocean wave? Now I know you have
    absolutely no engineering knowledge. First electricity forms
    a complete path from cloud to earth. Then as the current
    increases within everything in that circuit, then something
    eventually fails. Without the complete circuit, there can be
    no electricity flow. That means first electricity flows
    through everything in that circuit. Later something in that
    circuit fail. Typically the entire surge is done in
    microseconds. But the component can even take milliseconds to
    fail. Electricity does not flow through devices like an ocean
    wave - except where myths are promoted.

    A simple principle is taught in Electromagnetic wave theory
    - something taught to second year engineering students. Apply
    electricity to a long wire. Where does voltage first appear?
    Those who think of electricity in terms of ocean waves would
    say voltage first appears where electricity connects to that
    wire. They would be wrong because they did not learn
    basic electrical principles. Instead, voltage first appears
    at the far end of a wire. Again, a simple principle taught in
    wave theory.

    You are absolutely wrong that the charge, rolling down the
    wire like an ocean wave, uses the first possibility to unload
    itself. Wild speculation based upon junk science reasoning -
    that electricity flows like ocean waves.

    Classic modem damage is a circuit from cloud to earth. Only
    after current flows through everything in that circuit, does
    component failure occur. The component most often damaged by
    an AC mains surge is in the DAA section - where phone wire
    carries the current out of the modem to earth ground.

    And again, if a surge is incoming on phone line, then why
    does the always present phone line protector - installed free
    by the telco - get ignored by the surge? Only if Roger did
    not know the protector exists. Please explain why surges would
    enter on a utility wire with 'whole house' protector AND not
    enter on the utility wire that has no protector? Why would a
    surge be created on a wire both lower and protected by the AC
    mains wire? Clearly the incoming surge comes from the wire
    highest on pole AND via wire that has no 'whole house'
    protector - AC electric. Clearly, you do not even know that
    phone line protector exists.

    Furthermore, you are inventing new ideas on how electricity
    works. Clearly you have no engineering training. Therefore
    you are attacking my experience and credibility so that others
    will be confused. You have no idea how electricity works.
    Posting as if your entire electrical knowledge was in swapping
    computer boards or because you sell consumer electronics with
    highly profitable plug-in protectors. Again, where on that
    long wire does a voltage first appear? At the end connected
    to an electricity source (just like an ocean wave)? Or at the
    far end of the wire. It is electricity - not an ocean wave.
    Where does the voltage first appear?

    Since voltage first appears at the far end of a wire, then
    your wild speculation about what component is first damaged is
    bogus. You believe the first component damaged is "a
    component close to the input connection". That assumes
    voltage first appears at the input connection. It does not.
    According to your reasoning, the first component to be damaged
    due to "power unloading itself" would be the *last*
    component. The last component in that circuit would be the
    first to see voltage from a surge using your reasoning.
    Please do not invent electric concepts in a vacuum. Please
    first learn how electricity works. Electricity first flows
    through everything in that circuit. Only then does something

    You are having difficulty even with concepts taught to first
    year engineering students. That would explain why you hope a
    plug-in protector is doing even what the manufacturer will not
    claim. Its really a simple principle. A surge protector is
    only as effective as its earth ground - which also explains
    why the modem surge does not enter on phone line.

    The original poster is encourages to place a 'whole house'
    protector on the one utility that typically has no surge
    protection - AC electric. Other wires such as phone line and
    cable should already have protection, in part, because those
    connections are required by National Electrical Code - for
    other technical reasons.
  6. w_tom

    w_tom Guest

    Effective protection is not possible by unplugging. First,
    you are not available even one third of the day. Most of the
    time is spent sleeping or out working, etc. Second, many of
    those appliances cannot be always unplugged - ie answering
    machine, phone, and that TV. Having spent many decades
    learning this stuff, I now have equipment on during
    thunderstorms - often following the storm in real time. No
    damage because money was not wasted on grossly overpriced
    protectors recommended by urban myth purveyors. Provided is
    both the superior protection method AND the less expensive
    method. It is called 'whole house' protector. So effective
    that the phone company installs one for free in your phone
    line premise interface.

    Wires most often struck are wires highest on the pole. These
    wires make a direct connection to every household appliance
    without any earthed 'whole house' protector. Earthing the
    direct strike is essential to protection. One minimally
    acceptable 'whole house' protector is sold in Home Depot as
    Intermatic IG1240RC. Many other responsible manufacturers
    such as Leviton, Square D, Cutler Hammer, Erico, Polyphaser,
    Furse, etc all sell these products. But still we have people
    foolishly recommending plug-in protectors. When challenged,
    we discover they have no basic electrical knowledge - which
    explains why they did not even know the phone line protector
    already exists. Then when those plug-in protectors fail, they
    say nothing can protect from lightning - and recommend more of
    those ineffective protectors.

    One can never unplug for effective protection. The human is
    not reliable enough nor available 24/7. But 'whole house'
    protectors connected 'less than 10 feet' to earth ground are
    that reliable.

    Rich, you had to rearrange transistor leads because Japanese
    use ECB configuration verses an American EBC configuration?
  7. w_tom

    w_tom Guest

    Roger - chances are I was experimenting with this stuff
    before you existed. It is quite likely that I had my first
    engineering degree before you were walking. Polyphaser
    equipment was defined for someone who does not even have first
    year engineering education. Earthing a surge must be
    accomplished with very short wire - as close to the single
    point earth ground as is possible. And so the Polyphaser
    device mounts directly ON earth ground. That distance being
    that critical to effective surge protection.

    Yes we cannot make a perfectly conducting earth ground. So
    we also make the earth beneath a building equipotential. We
    enhance earth ground using Ufer grounds and halo grounds. But
    again, such conductors are not perfect. Even with a metallic
    earth ground, we still do not have equipotentail. Therefore
    we attempt to ground everything in the building to a the best
    conductive single point ground. We conduct the surge aways
    from the building as best we can. And we make the building
    and its underlying earth a short of faraday shield. These are
    compromises. But together, they are sufficient to avoid surge
    damage. It is why we best put the surge protector directly ON
    the single point earth ground. Shorter connection to earth
    ground means the protector is more effective. Again, a
    protector is only as effective as its earth ground.

    All this is well beyond the original poster's question. But
    it explains why he wants a 'whole house' protector and why
    plug-in protectors don't create these protective equipotential
    shells as was advocated.

    Obvously if a power strip protector if not earthed, then it
    leaves adjacent electronics at thousands of volts with many
    other and destructive outgoing paths. Nothing in a room can
    remain at thousands of volts in isolation. If the computer
    and power strip rise to 13,000 volts, then that voltage will
    create other destructive paths to earth ground (see next
    paragraph). Again, a power strip manufacturer claims only
    normal mode protection. Plug-in protectors cannot provide
    effective protection because they are too far from earth
    ground - effectively not earthed. No earthing means no
    effective protection.

    To be effective, the single point ground must be building
    wide because building interiors are chock full of 'surprise'
    conductive paths. For example, conductive paths include
    linoleum tile and some wall paints. These too must be
    connected to a power strip surge protector for that protector
    to be effective. They are not. If the power strip and
    computer rise a few thousand volts during the surge, then that
    voltage finds a destructive path to earth ground via mouse
    cable where cable contacts wall paint or baseboard heat. The
    power strip protector concept, as advocated, only works if the
    entire room was constructed, in advance, to be a farady cage.
    Neither the orignial poster nor others here have room
    constructed that carefully.

    Even in high reliablity facilities such as telephone
    switching centers, cell phone towers, and commercial broadcast
    centers, we install effective 'whole house' protection. The
    simplest, least expensive, and most effective way to protect
    household electronics is also the 'whole house' protector with
    a single point earth ground as required by post 1990 National
    Electrical Code requirements. Then the entire building rises
    and falls equipotentially during a surge. Again, we want the
    protector short to earth ground and farther from the protected
    electronics for two reasons. We want the surge conducted to
    earth using the most conductive path. And we want the entire
    building to rise and fall equipotentially.

    Furthermore that 50 foot of 12 AWG AC wire inside wall
    contributes to computer protection if we use a 'whole house'
    protector. Using a plug-in protector, then that 12 AWG wire
    instead contributes to computer surge damage. So many reasons
    why the less expensive 'whole house' protector is also so much
    more effective.

    Spend $15 or $50 to protect each appliance in the building.
    Or spend about $1 per protected appliance for a 'whole house'
    protector - that actually does what that power strip can only
    hope to accomplish. The 'whole house' protector does that
    task at tens of times less money AND can protect everything.
    Even if the power strip protector protects a computer, it
    leaves everything else in the building exposed. Why spend so
    money on a device that 1) does not even claim to protect from
    all types of surges and 2) costs tens of times more money per
    protected appliance?

    A surge protector is only as effective as its earth ground
    which is why a properly protected facility installs 'whole
    house' type protectors. More protection. Less money.
    Includes the essential 'less than 10 foot' connection to earth

    Anything that a power strip protector will accomplish is
    already inside those appliances. But those appliances assume
    the destructive surge will be earthed before entering a
    building. Technology well understood even before WWII. These
    plug-in protectors must have us ignore earth ground to make
    the sale. No earth ground means no effective protection.
    Again, I may have been doing engineering longer than you have
  8. w_tom

    w_tom Guest

    IOW the giant electrical wave appears just about equally on
    everything in the circuit. That is your delta wave.
    Virtually everything is located in the same part of the wave
    meaning there is near zero voltage difference.

    Surges are done in microseconds. Things go bang in
    milliseconds. How do you explain the discrepancy? Its quite
    simple. Damage occurs to the circuit component that is
    weakest and that absorbs excessive power. But that means
    everything is exposed to the current equally. Correct.
    Everything is exposed to the same circuit. How do we know?
    The surge is done in microseconds. The damage (ie a fuse
    blows) in milliseconds.

    He is quite silly to claim electricity flows like a wave as
    are you. Your claim that electricity appears like an ocean
    wave denies basic EM theory. Where does the voltage first
    appear? At the far end of the wire.

    Well this three reasons why it is silly to think the first
    component always fails. Are you also an electronic appliance
    salesman? How do you explain the contradiction between wave
    theory and your claims? How do you explain the time
    difference between a surge and when the damage physically

    Moving on - since phone lines already have effective 'whole
    house' protectors AND if the first electrical component
    encountered is the first one damaged, then why is the first
    damaged component on the phone wire side. How, pray tell,
    does the surge ignore a properly earthed surge protector to
    enter modem on phone line side? And why does the wire highest
    on pole - wire that enters building without an earthed 'whole
    house' protector - not carry the surge into a modem. How is
    the first component in modem damaged when the surge cannot
    even enter from that direction?

    Please explain how a surge routinely bypass AC electric
    wires to strike phone wires AND then completely ignore the
    telco provided 'whole house' protector. This is only possible
    if we reinvent electricity to meet our fictions.

    Don't be so foolish. Electricity first flows through
    everything in the circuit. Only then does something fail.
    Everywhere except in science fiction.
  9. P.T. Breuer

    P.T. Breuer Guest

    Don't be silly. His point is that anything close to the entry (and
    exit) point is a winner in the low resistivity stakes. Anything further
    away will see a lower EMF, since current is flowing through the
    conductors that supply that emf. So the closest things are likely to go
    bang first. When they have gone bang, the next thing along might also
    go bang.

    And yes, electricity DOES flow like a wave. It's called the delta
    response curve (in a circuit with parallel capacitance and serial
    resistance). And a lightning strike is a big delta.

  10. P.T. Breuer

    P.T. Breuer Guest

    Never heard of it, and I have my PhD in electrical engineering from U.
    Cam. Oh well.
    He doesn't care, and neither do we, since as he pointed out, the
    equipment doesn't care if it's earthed or not! That's why airplanes
    keep right on flying when hit by all that electrickery ...

  11. P.T. Breuer

    P.T. Breuer Guest

    Sure it does, at different amplitudes! Simultaneously at high amplitude
    near the strike, and low amplitude far away from the strike. As the
    "ocean wave" rolls on, the amplitude rises farther away.
    Uh, "delta wave" is not a term known to me, but it's cute, and I'll
    accept it!
    This is simply not so - for current to flow at all there has to be a
    difference of voltages. But if you are trying to say that
    free-floating, unearthed (and well insulated from earth :) equipment is
    safe because it experience zero voltage difference across it, I'd
    agree! Let's all continue using airplanes.
    Hey, let's not forget nanoseconds.

    No, I can't take this very seriously.
    Well, your point is what? That after a millisecond the first capacitor
    across the rails blows apart? Personally, I wouldn't have given it more
    than a few microseconds, but who's counting. Well, while it was taking
    current it was keeping the voltage across it nicely down, in
    conjunction with the huge voltage drop across the conductor (better
    termed "resistor") leading to it. So it "protected" the rest of the
    circuit for a bit, and then it popped, rather like the old waistcoat
    button, straining the next one ...
    Oh ho ho!
    Except that you have forgotten that it has to get there first. And to
    do that it has to get past a whole lot of other things that might well
    be stronger, but which have to last out until then ... it's an
    interesting exercise to compute the power time integral across
    differnet bits of circuit and see which hits the limit first. My money
    would be on the first parallel component in line, most of the time.

  12. Ron Reaugh

    Ron Reaugh Guest


  13. Ron Reaugh

    Ron Reaugh Guest

    Possibly but NOT before ME, loonie.
  14. Ron Reaugh

    Ron Reaugh Guest

    And may the force be with you, you sure need something.
  15. If you do a google search on his name, and you'll see he pops up like
    clockwork whenever anyone mentions surge protectors, to spout his own
    brand of 'myths'.

    I thought he might quieten down a little after the hosing down he got on late last year, but doesn't look like it.

    Noel Bachelor noelbachelorAT(From:_domain)
  16. Ron Reaugh

    Ron Reaugh Guest

    After faithfully doing this chinese firedrill for many years now and never
    having even heard of anyone personally who has gotten anything fried, I'm
    wondering if/when the day will come when I say to myself...enough of this BS
    and just party on during the storm<g>.
  17. Joe Davis

    Joe Davis Guest

    After faithfully doing this chinese firedrill for many years now and never
    I unplug my laptop from the AC and go on battery power. I'm connected to
    the internet via my wireless router--if that takes a hit, all I lose is a
    $75 box.
  18. Kent Wills

    Kent Wills Guest

    I was just walking down the street, when someone handed me a piece of
    paper. I thought it was something for a free meal at Popeye's
    Chicken. Instead, I found that on 20 Sep 2004 19:37:36 -0700,
    Odds are you would be safe, but it's certainly not dumb to
    disconnect. It's far better to KNOW your computer is safe than to
    take the risk and learn it's not.

  19. Suraj Singh

    Suraj Singh Guest

    Surprised to see that no body talked about the capacitance of the
    earth in this discussion.

    Lightening do not bother to hit the airplane. Even if it does it do
    not damage anything. Airplane capacitance is too small so a very
    minute flow of charge can change its potential to match the cloud
    potential. flow of minute change means little current ( micro amp)
    which wont damage anything.

    Imagine a situation where the plane has just taken off the ground,
    lightening strikes its body and discharge to the earth through bottom
    including pointed antennas in the wings; you can imagine the damage to
    the circuit from where the antenna is connected.

    As per the lightening is concerned one can not ignore earth if you are
    close to it. You can dare to ignore if you are a much bigger mass
    than earth.

    You can raise the common mode potential of the system (say PC and
    Modem), it helps but up to what extent? The charge on it will seek the
    earth and if a short and quick high conducting path in not provided,
    it may break down the air gap and discharge to the nearest path to
    earth through the mouse wire.

    Concept of GPR will provide much better protection if the whole house
    is considered as a sub system. It will be economical too.
    Power strips provide protection but for small surges only.

    Best regards,
  20. Ron Reaugh

    Ron Reaugh Guest

    Nope, the full charge and current hits the airplane.
    Just no.
    If that happens then the antenna gets fried. Study up.
    NO, through your toes first.
    OH NO another whole world surge protection wacko.
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