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EMP and Faraday Cages
EMP stands for electromagnetic pulse. A sufficiently strong pulse induces currents in conductors, and small unshielded electronics with long attached leads are the most vulnerable.
What a Faraday cage does
A Faraday cage is a continuous conductive enclosure. Incoming fields induce currents in the shell, which cancel the field inside. Three things determine whether it works:
- Continuity. The conductive layer must be unbroken. A seam that is taped rather than conductively bonded is a hole.
- Insulation. Contents must not touch the conductive shell. A cardboard box inside a metal trash can is the classic arrangement.
- Closure. The lid must make contact all the way around. Copper tape along the rim is a cheap fix.
A galvanized steel trash can with a tight lid, contents boxed in cardboard, is a genuinely effective cage. It does not need to be grounded to protect its contents — grounding matters for personnel safety, not for shielding.
What to put in it
Spares, not primaries: a backup handheld radio, a spare charge controller, an old laptop with offline references, a spare inverter board. Anything already plugged into long wiring during the event is likely lost regardless.