Faraday Cage

Faraday Cage

What is a Faraday Cage

A faraday cage is shielded enclosure made from metallic material that protects against the effects of electromagnetic energy.

Electromagnetic Shields can protect your electronics from exposure to electrostatic discharges produced from an electromagnetic pulse (EMP), solar flares or lightening strikes.

Why is it important to know about faraday cages?

If you can protect your electronics from, let's say, an EMP, you can continue to communicate or receive communications from others while those around you cannot.

In the case of an EMP, this effects a large region, so you may be the one person in your area who can continue to reach "the outside world" while normal communications are down. An EMP is so strong that a single detonation 200 to 400 miles over the center of the continental United States would fry every unprotected computer chip from coast to coast, and from the middle of Canada to the middle of Mexico.

Consider the damage from solar flares, too. Solar flares (sometimes also associated with a coronal mass ejection) are capable of extreme damage to modern computerized equipment! You can protect yourself to an extent by keeping a Hand Crank Radio on hand, but it even then, unless your electronic equipment is protected from an electromagnetic pulse, it will be fried! The solution is to have a faraday cage and keep your electronics inside when you anticipate something happening.

Make it Yourself

Faraday cage material: Electric fields are best conducted by materials that conduct electric current - silver, copper, and aluminum is 60% of copper. Iron/steel is farther down the scale. Aluminum is a good poor man's foil against an EMP; double wrap it to be safe.

The instructions below are from Jed Daniels.

Step one: buy the necessary components.

Here is a list:

  1. Two 8" lengths of 2" x 2" wood (I choose spruce "furring" strips, cause they were cheap at the local hardware store). This will be the main frame.
  2. One 8" length of 2" x 1" wood (again, spruce furring strips, even cheaper). This will be frame for the hinged lid.
  3. Hinge to attach lid to frame. I choose a 12" piano hinge.
  4. Aluminum screen to cover. I made some rough calculations and bought 10" of 36" wide mesh.
  5. Copper wire for the group connection. I choose green 14 AWG stranded, cause it was reasonably cheap.
  6. A bolt, some wing nuts, and washers to secure the copper wire to the mesh.
  7. A plug the I could attach the copper wire to and insert into a socket.
  8. Screws and staples to secure the frame together and the mesh to the wood (I simply used what I had laying around in my garage).

Instructions on How to Build a Faraday Cage

Step two: Cut the wood. I cut the 2" x 2" furring strips into four 18" lengths and eight 12" lengths. And the 1" x 2" strip into two 18" lengths and two 12" lengths.

Step three: Screw the frame together. This isn’t rocket science, so I’m not gonna give you detailed instructions on this part. Just remember to drill pilot holes for your screws so you don’t split the wood. Here is the assembled frame.

Step four: Build and attach the lid. I simply screwed the 1" x 2" pieces I had into a square and put them on the frame box with a piano hinge.

Step five: Attach the screen mesh. I will never regret the day I bought my air compressor and pneumatic stapler. I can only imagine the terrible hand cramps had I attempted this with a standard spring loaded stapler. If you don’t have a pneumatic stapler, I highly recommend you at least look into purchasing an electric one. To make sure that everything was tight, I tried to keep staples no more than 2 inches apart (usually about 1 inch, but towards the end I got a little tired and lazy, so the space between increased a littler).

Step six: Attach the ground wire. Attaching the parts was pretty simple.

I cut off the two prongs that get electricity. I wanted it to be perfectly clear that this plug is non-functional, and won’t create an electrified cage (cause that is a completely different project!). [NOTE: This is dangerous! Don't do it. If there are some cables crossed or your ground is wired incorrectly, you could create a lethal situation and die. Get an electrician to get you a dedicated ground wire to use for a project like this. If you kill or seriously injure yourself, don't blame me, I told you not to do this. Seriously, I'm not joking. Don't plug stuff into an outlet that connects to bare metal that you will be touching. That is just stupid.]

Step seven: Time to test! I plugged in the ground, got my laptop and started measuring Wi-Fi signals.


Building instructions provided by Jed Daniels:


As an alternative, if you don't want to make your own, but want something to protect your electronics. This is an awesome Faraday Duffel Bag. It is made of ballistic fabric, so it is extremely sturdy. You can also shield multiple electronics devices at the same time.