Build a Faraday Cage: What Is it, and 3 DIY Methods

In recent decades, the topic of electromagnetic pulses (EMP) and coronal mass ejections (CME) has gained more interest within mainstream circles. Considering how dependent we have become on technology in our daily lives, the awareness of this issue is a positive step forward. In this article, I will cover all you need to know about a Faraday Cage.

EMP & CME

Build a Simple Faraday Cage

Here is a quick and dirty recap of what an EMP and CME are. For more details, read this article by me.

An EMP is a by-product of a nuclear explosion whereas a CME is a solar event. While there are differences between the two in terms of exactly what is affected and to what extent, both events have the potential to negatively affect electronic devices or the power grid itself. 

What is particularly interesting, and terrifying, is that because these are invisible waves of energy that do not harm the human body, when one of these events happens you may not even be aware of it. That is until you realize the power is out. 

What is a Faraday Cage?

Faraday Cage

Much of our important documentation, photos, family history, medical information, and other sensitive material is in digital format. Luckily, there is a way to help protect all of the above and other devices that you deem important. To do so, you have to put the devices into a faraday cage. 

A faraday cage is simply a cage or some type of enclosure made from a conductive material. The conductive exterior material, usually metal, shields the contents within from electrical fields outside of the cage.  

This means that if you place your devices, say a phone or a laptop, into a faraday cage before an EMP or CME happens, they should be protected. There are faraday bags that can be purchased which are supposed to function in this same manner. I have never owned one so I cannot say to what extent they work. However, this article is about building a simple Faraday cage so that is what I will be focusing on.

One Last Bit…

One last quick thing to note about faraday cages is that when a device is inside, it will not receive any outside signals. For example, if you put your smartphone inside while it is powered on it will not receive text messages, the internet cannot be accessed, phone calls will not go through, and GPS will not be functional. Ever hit a dead spot inside of an elevator? Same principle.


Building a Faraday Cage: DIY Methods

Below are a couple of simple and affordable faraday cages that you can make that will help to protect your devices. 

Aluminum Garbage Can

I don’t tend to see these too much anymore since most garbage disposal companies started handing out universal trash and recycling receptacles. But I have noticed that they can still be picked up at hardware and big box stores for around $20. Smaller versions of these that resemble pales or buckets are also available. 

Once you have the container, you are going need to insulate the interior with a non-conductive material like bubble wrap or foam. This prevents contact between the devices and the metal container. For the best protection, make sure that the device is protected by this insulation on ALL sides. 

Ammo Boxes

Metal ammo boxes have become another popular container to use because many people already have them. To convert it into a faraday cage, follow the steps above for insulating the interior. The downside to this container is that they are quite small which limits the type of items that can be stored inside.

Also, the gap under the lid that the rubber gasket creates has the potential of being a breach point. For optimal protection consider wrapping a piece of foil tape around these possible points of entry.  

Ultra Cheap Container 

The following is going to be one of the cheapest options for making a faraday cage because you most likely have the majority of the materials in your house. Here are the items you are going to need for making a faraday box.

  • A cardboard box 
  • Duck tape or better yet, foil tape
  • Scissors or a utility knife 
  • Bubble wrap or Styrofoam 
  • Heavy-Duty aluminum foil 

The first item of business is to find the right size box. Luckily, there is no right size box as anyone that your devices will fit in will work. 

Next line the box with foam, bubble wrap or any non-conductive material. If you are using foam cut it to fit inside the box. Then cut it in half and hollow out the middle so that the devices can be nestled inside.

If you are using bubble wrap, line the inside of the box with the plastic and then wrap the devices in the bubble wrap as well. Both of the above materials will not only help to insulate the items away from the container walls but will help to physically protect the device if the box is dropped. 

With the insulation and devices safely inside the box, close the top or seal the flaps down with duct tape. The last step is to simply wrap the entire box with aluminum foil and tape down the ends. If you want additional reassurance with the exterior, go ahead and wrap an extra layer or two of foil around the box. 

You now have your very own Faraday cage that is affordable, simple to construct and doesn’t take too much time to complete. That is the good news. The not so good news is that this type of Faraday cage is not easily accessed. Because of that, this type of container is best used for backup devices that are not used all that often. Or for an event that you have time to prepare for, which would most likely be a CME.


Faraday Locations and What To Put In Them

You can have a faraday cage filled with backup gear and items at a bugout location if you so choose. But there are two primary locations that I feel should have one at all times. At home and in your vehicle. Given the space available, the cage at home can be as large as you want and therefore can store larger items or more of them.

Here are a few items to consider putting into a faraday cage. 

  • A flashlight or headlamp: Consider ones that use common batteries such as AA, or lights that are rechargeable or solar-powered. Emergency candles are great but in the event of a long term power outage, I doubt anyone has stored enough of them to last. Plus, candles can be problematic around flammable materials or using them while on the go. Save yourself the trouble and pack a flashlight. 
  • Communication: There are three different types of radios that I think of when it comes to communications. A HAM radio, a pair of walkie talkies, and an AM/FM radio. The problem here is that depending on the type of event and severity, using these devices may or may not work. But it would certainly be better to have them then not to have them. Now an AM/FM radio is not a two-way street, but if broadcasting is still occurring it will give you a means of knowing what is going on. 
  • Any type of gear that has electronic components that you will need, should go in the box. 
  • A small solar panel and charger would also be a good idea. When one of these events occurs, it is highly probable that the power grid will be affected or knocked out. A way to charge any of the devices you put into your box will be helpful.

Wrap Up

After reading this article I hope that you now know what a Faraday cage is, how to make one, and when to use it. Because the when could be right after you finish reading this sentence.

To be prepared, read our detailed guide on creating a blackout survival kit.



Written by Bryan Lynch

Bryan grew up in the Midwest and spent every waking moment outdoors. Learning how to hunt, fish, read the land and be self-reliant was part of everyday life. Eventually he combined his passions for the outdoors, emergency preparedness, and writing. His goal was to spread positive information about this field. Recently, Bryan authored the book Swiss Army Knife Camping and Outdoor Survival Guide. Read more of Bryan's articles.

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