My husband has done a lot of research on ways to protect at least some of our electronics from an electromagnetic pulse (EMP). The bottom line appears to be that no one knows absolutely for sure what will work. It is impossible to test EMP protective measures at home using real EMPs. We used an AM/FM radio and a pair of walkie talkies to test how well different blocking methods work. Our results may or may not apply to magnetic pulses.
We tried the following items as EMP barriers.
Ammo can
Faraday bag
Mylar bag
Aluminum foil
Galvanized trash can
Microwave oven
Conventional oven
Results
First, we learned that almost anything helps at least a little and is better than nothing. Second, in order to be protected from a magnetic pulse, the item needs to be insulated from touching any metal. Third, multiple layers of protection are most effective.
The best system we found based on research and our experiments is to do the following:
- Vacuum seal electronics like radios in a FoodSaver bag which acts as an insulator,
- Wrap it in a double layer of heavy-duty aluminum foil wrapped tightly with no gaps
- Vacuum seal it again to insulate the foil from touching any metal,
- Place in a sealed metal ammo can.
We were surprised how poorly the the metal containers, microwave, and oven worked without the aluminum foil. However, the microwave and oven still had their cords. Reportedly, if you use an old microwave, you should remove the cord because it acts as an antenna preventing it from blocking the EMP. We are also using a new galvanized trash can for some larger items instead of an ammo can.
We bought a couple of Faraday bags and tested them in comparison to our regular Mylar storage bags. The Faraday bags were a couple of millimeters thicker, but did not block radio signals any differently than the regular storage Mylar. Both reduced the radio waves getting through, but did not eliminate them. Something packed in a Faraday bag or Mylar bag doesn’t have to be insulated in plastic since the bags have insulating layers on the inside and outside with the metal layer sandwiched between them. We are using the Faraday bags and Mylar bags with ziplock closures placed inside an ammo can to store things that we use regularly and need easy access to, but want to protect.
The ammo cans and metal trash can that we are using to store equipment that we don’t need access to are spray painted light blue and are labeled with EMP stickers and the contents. The ammo can we use for easy access is painted lavender also with labels. Unpainted ammo cans are used for ammunition storage.
For Further Reading
Electromagnetic pulse impact far and wide–USA Today