EMP / Geo-magnetic Storm Basics

[Paul]

An EMP pulse is an EXTREMELY POWERFUL wide band burst of radio waves.

Usually generated by nuclear explosions it can also be caused by the sun.
There are non nuclear devices that can generate similar results.

It hurts things by inducing high voltages WAY OVER the working limits of the equipment.

An EMP pulse is VERY short duration. Seconds rather than minutes.

EMP can "hurt things" if:-

It's an electrical or electronic design,
It if's switched on or off,
Connected to power or not,
All connected up or in it's separate parts,

If it is outside a Faraday cage.

A Faraday cage is a metal box, all parts are bonded together, no holes.
It doesn't have to be "special metal", heavy, or expensive.
A metal Ammo box or metal biscuit tin is good enough.

Line it with a non conductive material like polystyrene sheet.
Everything placed inside should be in it's own conductive bag
i.e. Mylar bag, anti-static bag, or just wrapped in silver foil.

There is no need to bury or Earth this box.

A Faraday cage will NOT protect sensitive equipment from strong magnetic forces.
Some electronic compasses have VERY sensitive magnetic devices in them.

Geo-Magnetic storms ARE NOT THE SAME AS AN EMP.

These induce high voltages in LONG wires like pylons, telephone wires, and aerials.

This is what kills power distribution and long distance communications.
Simply disconnecting equipment from aerials and power outlets is enough to protect against Geo-magnetic Storms.

These storms can last for hours if not days.

However as any large metal structures MAY become VERY electrically charged and start to arc and spark, prudence says to put your "home based gear" into a Faraday cage for the duration of the storm.

Note: Long range radio communication including telephones can be affected by these storms.

You can use mobile radio equipment for communicating i.e. handhelds and car radios BUT they may be swamped with naturally generated noise i.e. static, whistling, low frequency "rumbles".