Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    More on EMP
    From: Dan Allen
    Date: 2003 Dec 29, 17:35 -0800

    has some good info about Electromagnetic Pulse or EMP.  Here it is:
    Copyright (C) Duncan Long 1989.  All rights reserved.
            EMP.  The letters spell burnt out computers and other electrical
    and perhaps even a return to the dark ages if it were to mark the
    beginning of
    a nuclear war.  But it doesn't need to be that way.  Once you
    understand EMP,
    you can take a few simple precautions to protect yourself and equipment
    it.  In fact, you can enjoy much of the "high tech" life style you've
    accustomed to even after the use of a nuclear device has been used by
    rorists--or there is an all-out WWIII.
            EMP (Electro-Magnetic Pulse), also sometimes known as "NEMP"  (Nuclear
    Electromagnetic Pulse), was kept secret from the public for a long time
    and was
    first discovered more or less by accident when US Military tests of
    weapons started knocking out phone banks and other equipment miles from
            EMP is no longer "top secret" but information about it is still a
    sketchy and hard to come by.  Adding to the problems is the fact that
    effects are hard to predict; even electronics designers have to test
    equipment in powerful EMP simulators before they can be sure it is
    capable of with standing the effect.
            EMP occurs with all nuclear explosions.  With smaller explosions the
    effects are less pronounced.  Nuclear bursts close to the ground are
    by the earth so that EMP effects are more or less confined to the
    region of the
    blast and heat wave.  But EMP becomes more pronounced and wide spread
    as the
    size and altitude of a nuclear blast is increased since the ground; of
    two, altitude is the quickest way to produce greater EMP effects.  As a
    device is exploded higher up, the earth soaks up fewer of the free
    produced before they can travel some distance.
            The most "enhanced" EMP effects would occur if a nuclear weapon were
    exploded in space, outside the Earth's atmosphere.  In such a case, the
    radiation released during the flash cycle of the weapon would react
    with the
    upper layer of the earth's atmosphere and strip electrons free from the
    molecules, producing electromagnetic radiation similar to broad-band
    waves (10 kHz-100 MHz) in the process.  These electrons would follow the
    earth's magnetic field and quickly circle toward the ground where they
    would be
    finally dampened.  (To add to the confusion, we now have two more EMP
    "Surface EMP" or "SEMP" which refers to ground bursts with limited-range
    effects and "High-altitude EMP" or "HEMP" which is the term used for a
    detonation creating large amounts of EMP.)
            Tactically, a space-based nuclear attack has a lot going for it; the
    magnetic field of the earth tends to spread out EMP so much that just
    one 20-MT
    bomb exploded at an altitude of 200 miles could--in theory--blanket the
    continental US with the effects of EMP.  It's believed that the
    surge of the EMP from such an explosion would be strong enough to knock
    much of the civilian electrical equipment over the whole country.
    this is a lot of "bang for the buck" and it would be foolish to think
    that a
    nuclear attack would be launched without taking advantage of the
    confusion a
    high-altitude explosion could create.  Ditto with its use by terrorists
    the technology to get such payloads into space become readily available
    smaller countries and groups.
            But there's no need for you to go back to the stone age if a nuclear
    occurs.  It is possible to avoid much of the EMP damage that could be
    done to
    electrical equipment--including the computer that brought this article
    to you--
    with just a few simple precautions.
            First of all, it's necessary to get rid of a few erroneous facts,
            One mistaken idea is that EMP is like a powerful bolt of lightning.
    the two are alike in their end results--burning out electrical
    equipment with
    intense electronic surges--EMP is actually more akin to a
    super-powerful radio
    wave.  Thus, strategies based on using lightning arrestors or
    grounding techniques are destined to failure in protecting equipment
    from EMP.
            Another false concept is that EMP "out of the blue" will fry your brain
    and/or body the way lightning strikes do.  In the levels created by a
    weapon, it would not pose a health hazard to plants, animals, or man
    it isn't concentrated.
            EMP can be concentrated.
            That could happen if it were "pulled in" by a stretch of metal.  If
    happened, EMP would be dangerous to living things.  It could become
    trated by metal girders, large stretches of wiring (including telephone
    long antennas, or similar set ups.  So--if a nuclear war were in the
    you'd do well to avoid being very close to such concentrations.  (A safe
    distance for nuclear-generated EMP would be at least 8 feet from such
    of metal.)
            This concentration of EMP by metal wiring is one reason that most e-
    lectrical equipment and telephones would be destroyed by the electrical
    It isn't that the equipment itself is really all that sensitive, but
    that the
    surge would be so concentrated that nothing working on low levels of
    ity would survive.
            Protecting electrical equipment is simple if it can be unplugged from
    outlets, phone systems, or long antennas.  But that assumes that you
    won't be
    using it when the EMP strikes.  That isn't all that practical and--if a
    war were drawn out or an attack occurred in waves spread over hours or
    you'd have to either risk damage to equipment or do without it until
    things had
    settled down for sure.
            One simple solution is to use battery-operated equipment which has
    or antennas of only 30 inches or less in length.  This short stretch of
    puts the device within the troughs of the nuclear-generated EMP wave
    and will
    keep the equipment from getting a damaging concentration of electrons.
    Provided the equipment isn't operated close to some other metal object
    within 8 feet of a metal girder, telephone line, etc.), it should
    without any other precautions being taken with it.
            If you don't want to buy a wealth of batteries for every appliance you
    or use a radio set up with longer than 30-inch antenna, then you'll
    need to use
    equipment that is "hardened" against EMP.
            The trick is that it must REALLY be hardened from the real thing, not
    EMP-proof on paper.  This isn't all that easy; the National Academy of
    recently stated that tailored hardening is "not only deceptively
    but also very poorly understood by the defense-electronics community."
    the US Military has equipment which might not survive a nuclear attack,
    though it is designed to do just that.
            That said, there are some methods which will help to protect circuits
    from EMP and give you an edge if you must operate ham radios or the
    like when a
    nuclear attack occurs.  Design considerations include the use of tree
    circuits (rather than standard loop formations); the use of induction
    around components; the use of self-contained battery packs; the use of
    antennas; and (with solid-state components) the use of Zener diodes.
    design elements can eliminate the chance an EMP surge from power lines
    or long
    antennas damaging your equipment.  Another useful strategy is to use
    wires for each separate instrument which is coupled into a system so
    that EMP
    has more paths to take in grounding itself.
            A new device which may soon be on the market holds promise in allowing
    electronic equipment to be EMP hardened.  Called the "Ovonic threshold
    it has been created by Energy Conversion Devices of Troy, MI.  The
    threshold device is a solid-state switch capable of quickly opening a
    path to
    ground when a circuit receives a massive surge of EMP.  Use of this or a
    similar device would assure survival of equipment during a massive
    surge of
            Some electrical equipment is innately EMP-resistant.  This includes
    large electric motors, vacuum tube equipment, electrical generators,
    formers, relays, and the like.  These might even survive a massive
    surge of EMP
    and would likely to survive if a few of the above precautions were
    taking in
    their design and deployment.
            At the other end of the scale of EMP resistance are some really
    electrical parts.  These include IC circuits, microwave transistors,
    and Field
    Effect Transistors (FET's).  If you have electrical equipment with such
    ponents, it must be very well protected if it is to survive EMP.
            One "survival system" for such sensitive equipment is the Faraday box.
            A Faraday box is simply a metal box designed to divert and soak up the
    EMP.  If the object placed in the box is insulated from the inside
    surface of
    the box, it will not be effected by the EMP traveling around the
    outside metal
    surface of the box.  The Faraday box simple and cheap and often
    provides more
    protection to electrical components than "hardening" through circuit
    which can't be (or haven't been) adequately tested.
            Many containers are suitable for make-shift Faraday boxes:  cake boxes,
    ammunition containers, metal filing cabinets, etc., etc., can all be
    Despite what you may have read or heard, these boxes do NOT have to be
    tight due to the long wave length of EMP; boxes can be made of wire
    screen or
    other porous metal.
            The only two requirements for protection with a Faraday box are:  (1)
    equipment inside the box does NOT touch the metal container (plastic,
    paper, or cardboard can all be used to insulate it from the metal) and
    (2) the
    metal shield is continuous without any gaps between pieces or
    extra-large holes
    in it.
            Grounding a Faraday box is NOT necessary and in some cases actually
    may be
    less than ideal.  While EMP and lightning aren't the "same animal", a
    example of how lack of grounding is a plus can be seen with some types
    lightning strikes.  Take, for example, a lightning strike on a flying
    plane.  The strike doesn't fry the plane's occupants because the metal
    shell of
    the plane is a Faraday box of sorts.  Even though the plane, high over
    earth, isn't grounded it will sustain little damage.
            In this case, much the same is true of small Faraday cages and EMP.
    Consequently, storage of equipment in Faraday boxes on wooden shelves
    or the
    like does NOT require that everything be grounded.  (One note:
    non-grounded boxes might hold a slight charge of electricity; take some
    and care before handling ungrounded boxes following a nuclear attack.)
            The thickness of the metal shield around the Faraday box isn't of much
    concern, either.  This makes it possible to build protection "on the
    cheap" by
    simply using the cardboard packing box that equipment comes in along
    aluminum foil.  Just wrap the box with the aluminum foil (other metal
    foil or
    metal screen will also work); tape the foil in place and you're done.
    it is kept dry, the cardboard will insulate the gear inside it from the
    placing the foil-wrapped box inside a larger cardboard box is also wise
    to be
    sure the foil isn't accidentally ripped anywhere.  The result is an
    Faraday box with your equipment safely stored inside, ready for use
    following a
    nuclear war.
            Copper or aluminum foil can help you insulate a whole room from EMP
    as well.  Just paper the wall, ceiling and floor with metal foil.
    Ideally the
    floor is then covered with a false floor of wood or with heavy
    carpeting to
    insulate everything and everyone inside from the shield (and EMP).  The
    catch to this is that care must be taken NOT to allow electrical wiring
    connections to pierce the foil shield (i.e., no AC powered equipment or
    antennas can come into the room from outside).  Care must also be taken
    the door is covered with foil AND electrically connected to the shield
    with a
    wire and screws or some similar set up.
            Many government civil defense shelters are now said to have gotten the
    Faraday box, "foil" treatment.  These shelters are covered inside with
    foil and have metal screens which cover all air vents and are connected
    to the
    metal foil.  Some of these shelters probably make use of new optical
    systems--protected by plastic pipe--to "connect" communications gear
    inside the
    room to the "outside world" without creating a conduit for EMP energy
    to enter
    the shelter.
            Another "myth" that seems to have grown up with information on EMP is
    nearly all cars and trucks would be "knocked out" by EMP.  This seems
    but is one of those cases where "real world" experiments contradict
    answers and I'm afraid this is the case with cars and EMP.  According to
    sources working at Oak Ridge National Laboratory, cars have proven to be
    resistant to EMP in actual tests using nuclear weapons as well as
    during more
    recent tests (with newer cars) with the US Military's EMP simulators.
            One reason for the ability of a car to resist EMP lies in the fact that
    its metal body is "insulated" by its rubber tires from the ground.  This
    creates a Faraday cage of sorts.  (Drawing on the analogy of EMP being
    to lightning, it is interesting to note that cases of lightning
    striking and
    damaging cars is almost non-existent; this apparently carries over to
    effects on vehicles as well.)
            Although Faraday boxes are generally made so that what is inside
    touch the box's outer metal shield (and this is especially important
    for the
    do-it-yourselfer since it is easy to inadvertently ground the Faraday
    by putting the box on metal shelving sitting on a concrete floor), in
    case of the car the "grounded" wiring is grounded only to the battery.
    practice, the entire system is not grounded in the traditional
    wiring sense of actually making contact to the earth at some point in
    circuitry.  Rather the car is sitting on insulators made of rubber.
            It is important to note that cars are NOT 100 percent EMP proof; some
    will most certainly be effected, especially those with fiberglass
    bodies or
    located near large stretches of metal.  (I suspect, too, that recent
    cars with
    a high percentage of IC circuitry might also be more susceptible to EMP
            The bottom line is that all vehicles probably won't be knocked out by
    EMP.  But the prudent survivalist should make a few contingency plans
    "just in
    case" his car (and other electrical equipment) does not survive the
    effects of
    EMP.  Discovering that you have one of the few cars knocked out would
    not be a
    good way to start the onset of terrorist attack or nuclear war.
            Most susceptable to EMP damage would be cars with a lot of IC circuits
    other "computers" to control essential changes in the engine.  The very
    may wish to buy spare electronic ignition parts and keep them a car
    (perhaps inside a Faraday box).  But it seems probable that many
    vehicles WILL
    be working following the start of a nuclear war even if no precautions
    been taken with them.
            One area of concern are explosives connected to electrical discharge
    wiring or designed to be set off by other electric devices.  These
    might be
    set off by an EMP surge.  While most citizens don't have access to such
    equipment, claymore mines and other explosives would be very dangerous
    to be
    around at the start of a nuclear box if they weren't carefully stored
    away in a
    Faraday box.  Ammunition, mines, grenades and the like in large
    might be prone to damage or explosion by EMP, but in general aren't all
    sensitive to EMP.
            A major area of concern when it comes to EMP is nuclear reactors
    in the US.  Unfortunately, a little-known Federal dictum prohibits the
    NRC from
    requiring power plants to withstand the effects of a nuclear war.  This
    that, in the event of a nuclear war, many nuclear reactors' control
    might will be damaged by an EMP surge.  In such a case, the core-cooling
    controls might become inoperable and a core melt down and breaching of
    containment vessel by radioactive materials into the surrounding area
    well result.  (If you were needing a reason not to live down wind from a
    nuclear reactor, this is it.)
            Provided you're not next door to a nuclear power plant, most of the ill
    effects of EMP can be over come.  EMP, like nuclear blasts and fallout,
    can be
    survived if you have the know how and take a few precautions before
            And that would be worth a lot, wouldn't it?
    The author of this article, Duncan Long, is well-known as the writer of
    gun, self-sufficiency, and survival books.  His firearms books are
    (along with other interesting books) in a free catalog available from
    Press, P. O. Box 1307, Boulder, CO 80306 (303) 443-7250.  Long's
    SURVIVAL is available for $14 from Long Survival Publications, 115
    Dr., Wamego, KS 66547.  Long has also recently had a post-nuclear war
    book, ANTI-GRAV UNLIMITED released from Avon Books (available from
    local book
    stores or from Avon Books, 105 Madison Ave., NY, NY 10016; for
    copy, send $4 to:  Long Survival Publications, address above).

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site