Build a Simple Faraday Cage in 5 Minutes

Faraday CageSimple, inexpensive homemade Faraday box

A Faraday cage can keep you in contact with the outside world during and after an emergency. Those living in an urban environment may be most susceptible to grid failures due to electronic terrorism or an EMP.

While the above simple Faraday box may not protect electronics from the strongest of electromagnetic pulses, at the very least, it will prevent prying ears and eyes from eavesdropping on you.

Help protect your sensitive personal information and expensive electronic equipment with a simple, cheap and effective homemade survival prep.

What is a Faraday Cage?

A Faraday cage (also called a Faraday box, or Faraday shield) uses a conductive metal, usually aluminum or copper, to reroute electrical charges. Essentially, it is a barrier that neither lets electrical waves in or out.

These cages block wireless satellite communications, radio and other electromagnetic waves, and heavy-duty versions can prevent damage to sensitive electronic equipment from lightning strikes to electromagnetic pulses (EMP).

Simply, it protects sensitive electronic equipment like cell phones, tablets, laptops, computers, cameras, GPS, short wave and ham radios, etc. from destructive electrical charges.

Watch the video below to see how effective even a simple one can be:

Is Your Phone Spying on You?

According to iOS forensic examiner Jonathan Zdzairski: Yes.

Code buried deep within the programming language can allow third parties to access your personal information through a USB connection or even wirelessly, whether you're using the phone or not at the time.

Many apps also store your personal data for advertising purposes and numerous government agencies, including the NSA, have allegedly tapped phones for surveillance without the owner's knowledge.


So if third parties can access your phone, even when it's idle or even turned off, what can you do for a little privacy?

Yank out the battery is one option. The other is to place the phone in a Faraday cage.

Proof that Simple Homemade Faraday Shield Works

Theoretically, if you happen to have your phone properly shielded during an EMP, and assuming of course that the nuclear bomb or solar flare responsible didn’t vaporize you, the surrounding cell towers, and satellites (not to mention the person you’re trying to call), you’ll still be connected to the outside world, while others fumble in the dark.

NOTE: Faraday boxes are all around us. Our appliances, cars, commercial buildings, metal storage sheds, etc. all function, to some degree, as electronic shields.

For instance, microwave ovens are designed to keep certain waves from escaping, which then cook your food and not you. (They don’t block cell phone service, though.)

Faraday Cage - microwaveFaraday shield for microwave oven door

Also, Faraday boxes should be grounded to properly disperse electrical charges. This can be as simple as placing the cage in direct contact with the ground, or connecting a wire from the box to a copper ground rod driven into the earth.

How to Make a Faraday Shield from a Cardboard Box

If you can wrap a Christmas gift, you can make a Faraday cage.


Faraday Cage
  • Cardboard box with removable lid (shoe boxes work well)
  • Aluminum foil
  • Tape
  • Scissors


1. Remove lid from box. The pieces need to be wrapped separately.

Faraday Cage

2. Cut pieces of aluminum foil large enough to completely warp around the box and lid in one piece if possible. If you must use multiple pieces, overlap sections of foil at least 2 inches.

3. Wrap the box and lid, then fold the excess foil to the inside. Take care not to tear the foil. If there is a rip the cage may not work.

Faraday Cage

4. Trim the foil to leave a small lip (less than 1 inch) around the top of the box and lid. Secure with tape.

Faraday Cage

5. To test, place electronics in box and cover tightly. Electronics must be insulated from the foil. Make sure absolutely no part of the electronics touches the foil. Cardboard works well as an insulator.

For more on the history and science behind this principle, click here.

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