Electromagnetic pulse (EMP), is now a commonly know effect thanks to movies
showcasing the nuclear version such as Goldeneye (James Bond) and the remake
of Ocean’s 11 which shows a non-nuclear version. The real question for
survivalists is: what is EMP actually going to do to my valued equipment and
what can I realistically do about it? Let’s start with lightening since
it is very well understood. We know that lightening will tend to seek out the
highest conductive point that is grounded and then seek to flow through a conductor,
often back and forth a few times, until the electrical charge imbalance between
the cloud and ground is neutralized. To protect buildings, lighting rods have
been erected on them historically to channel the electrical current around
the building and into the ground.
With EMP the concept of channeling the energy away from what we wish to protect
is somewhat similar. EMP is a pulse of energy, and travels through everything.
The idea is to shield something from it my placing it in (surrounding it with)
a conductive (metal) box that is then grounded (preferably into the earth).
The conductive box thus channels a large amount of the electrical energy passing
into it down the ground, sparing what is inside of it from the full force of
the electro magnetic pulse.
The good news is such a Faraday Cage or Faraday Shielding need not be expensive.
A metal file cabinet or inexpensive light weight gun safe will work. I bought
a used heavy metal box that I think was originally used to keep coal or sand
in. What you want is a complete and connected conductive metal (steel) exterior
surface,
not
a grid or cage with gaps (this is why the term Faraday Cage is actually not
a good term since with a cage people think of bars). [JWR Clarifies: Actually,
a cage-like structure would work, but the largest gap in the mesh would have
to be less than 1/4 of the wavelength of the expected pulse. Hence, 1/2" wire
mesh should be sufficient.] Ideally
you should connect a very heavy gage electrical wire (monster cable or 220
volt
heavy
electric
wire) to a stand-alone dedicated ground (usually a copper rod drilled in below
your basement floor). Some people say connect it to your copper plumbing or
steel pipes. The problem with this is that the pipes could act as an antenna
and actually channel energy to the Faraday shield. Just talk to an electrician
about putting in a ground.
Although the Faraday principal says the electrical items are safe inside as
long as they are not connected or touching the exterior shield, I think you
still have to worry about the spark gap. Thus my advice is to put your expensive
electronic stuff (computer, laptop, night vision, digital camera, radio equipment,
etc.) into plastic tubs with plastic lids, and that then into the Faraday Cage.
Plastic of course was developed as an insulator for radar in WWII, which due
to it’s high voltage had to have an insulator between metal parts so
the electricity didn’t just spark through the air (spark gap). Mineral
oil has also been used as an insulator in high voltage equipment.
Remember, having anything plugged in, or hooked to an antenna defeats the purpose
of shielding around it as you have provided an electrical highway [an unintentional
antenna] right in. The use of a [lightning protection fast] fuse on such necessary
plugged in
equipment is probably your best bet as I fear a circuit breaker is not going
to react
quickly
enough
to
save
delicate equipment. However, I am not an electrical engineer nor am I claiming
to be an EMP expert here. I am just trying to apply practical solutions to
the problem and welcome the constructive criticism or correct by others who
are more knowledgeable and can offer better solutions to the problem. - Rourke
http://groups.yahoo.com/group/survivalretreat
More on the subject:
Understanding EMP: http://www.geocities.com/CapeCanaveral/5971/emp.html
EMP Bomb: http://www.abovetopsecret.com/pages/ebomb.html
Faraday Cages: http://www.unitedstatesaction.com/emp_and_faraday_cages.htm#qst
Duncan Long on EMP: http://standeyo.com/News_Files/NBC/EMP.protection.html