One of the easiest ways to protect electronic equipment from the damaging effects of an EMP is to store them in EMP bags. The challenge becomes picking out bags that provide the highest level of shielding. Most bags sold on the internet have never even been tested for shielding effectiveness.
With a PhD in electrical engineering, I was fortunate enough to have the equipment to test numerous brands of bags for their shielding effectiveness. The bags sold here were shown to offer excellent protection, reducing incident fields by 50 dB (99.7%) across all relevant EMP frequencies (100 kHz to 1 GHz). That means that even a worst-case 50,000 V/m down would be reduced to 157 V/m – a level that most unpowered electronics would survive.
These bags are quite large, measuring 30″ L x 26″ W and are great for storing all sorts of electronics.
To seal these bags, simply fold the top down and clip or tape shut.
Please see the FAQs section to learn more about layering and sealing the bags.