alt.engineering.electrical

"JohnR66" wrote in message
news: $ @bgtnsc05-news.ops.worldnet. ...
> "Benj" wrote in message
> news: @ ...
>>
>> Wilscombe wrote:
>>> My understanding is that electrical equipment that is not "live" at
>>> the time of the EMF attack would not be affected. It would be wise to
>>> have any necessary batteries disconnected. Burying the items would
>>> serve no purpose, other than security.
>>
>> The way to protect gear that is not running is to place it inside a
>> sealed metal box (aluminum, copper, ect. The more conductive the
>> better) Note that the lid needs to be REALLY electrically sealed!
>> Usually RF "fingers" or Steel wool "O" rings are used to make contact
>> all around the lid. A simple wire to the lid just won't do it. For
>> small items, [Pack of CDs, DVDs, etc.] new empty paint cans are
>> perfect! Hey for fun put an old useless CD in your microwave! Great
>> way to get rid of your old "secret" files. Microwave might not be too
>> happy with the load, though.
>>
>> However, any power cord (plus all wires in house and out to power
>> transformer) makes an antenna for the EMP as does any actual antenna.
>> IF the gear is to be operational at the time you must set it up as you
>> would to protect from lightning. Arrestors, grounds etc. Unplugging
>> power cords and antennas helps save gear because it disconnects the
>> "antennas" that pick up the damaging EMI.
>>
> Just how powerfull are these EMP devices? How close do these have to be
> detonated? It takes a really close stroke of lightning to do damage to
> electronics. We had lightning strike the electric pole where the
> transformer feeds our house. The conducted/induced current damaged about
> half the electrical items in the house from the well pump motor to
> answering machines. Oddly, the computer and its modem were not harmed.

Not very close.

/wiki/Electromagnetic_pulse

One or two, so the theory goes, can knock out a significant area in the US.
The TV series Jericho showed a realistic (again, according to theory) event
where one nuke was detonated in the upper atmosphere, knocking out all sorts
of gadgets all over the nation.

The Faraday Cage is probably the only thing that can promise protection.
Theory again.

The problem with this issue is it's pretty much all theory. We know nukes
and other devices can create an EMP that can devastate electronics. We
don't know whether it can be done over a significant distance. This would
require a fairly large test, which most folks aren't too keen on doing.

For example, will an EMP have an effect on vacuum tube devices? Old, large
transistors? What about rebar in buildings, clouds, or other factors not
previously considered? Nobody knows for certain.

For small items such as two way radios, AM/FM radios, fancy LED flashlights,
and whatever else folks might need, it's best to store them in a solid,
metal container that, as other posters have mentioned, are electrically
sealed. A military type ammo box would be perfect, protecting the items
within from moisture and whatnot as well. Sand down to metal around the
seal, then duct tape a thick helping of steel wool around the seam. Won't
be pretty, but should survive a good long time.

However, batteries of any type should NOT be stored this way for any length
of time. They can leak, destroying your equipment. They also won't hold a
charge indefinitely. It would be wise to only store items that can use
off-the-shelf batteries, such as AA's, D's, and so forth. You can keep
two-way radio batteries around, especially if you have radios that you use
on a regular basis. Lithium Ion rechargeable batteries are a bad idea.
They almost always have electronic circuits in them to manage charging and
use, which would make them vulnerable to EMP damage.

CS