Simple Faraday Cage

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A homemade Faraday cage that will protect life-saving and useful electronics from an EMP (Electromagnetic Pulse) event is something that every prepper should have. It doesn’t need to be fancy, or complicated. It doesn’t need to be an entire room. There are DIY simple faraday cage designs that can be built quickly, with supplies on hand, and then kept in your garage, basement, attic, or vehicle as storage containers for those sensitive machines that you want to protect.

Let’s discuss EMPs, and why we need to shield our equipment from them.

What is an EMP?

An EMP (Electromagnetic Pulse) is a short burst of electromagnetic energy that is powerful enough to destroy electronic equipment. There are three major sources of these bursts. First is a very large solar flare from the Sun. Luckily large solar flares are not at all common and are very directional. So the likelihood of one big enough to affect us and aimed directly at Earth is pretty small, but still possible.

Second source of an EMP is from a nuclear warhead detonating on land. This would be a fairly contained EMP that radiates away from the warhead impact location. Though significant, the radiation effects of the nuclear warhead would be much more devastating than the EMP would be.

The third and scariest of the possible EMP options is a high-altitude electromagnetic pulse (HEMP). This is where a nuclear warhead is detonated hundreds of miles above the Earth’s surface. There is little to no radiation affects from these blasts. But the EMP effect is massive to fragile electronics below, for a range of hundreds to thousands of miles depending on the size of the blast. One large HEMP could affect all of Europe.

Any of these three sources would seriously compromise our modern infrastructure by destroying electronics that run our grid, including power stations, sewage facilities, modern airplanes, and modern vehicles. If you want to get a general idea of what life would be like after such an attack, take a look at some of the books on the Prepper Fiction page.

Michael Faraday simple faraday cage inventor

What is a Faraday Cage?

A Faraday cage–also know as a Faraday shield–really isn’t that complicated. Named after the English scientist Michael Faraday, who invented them in 1836, a simple Faraday cage is just an enclosure made of a non-conductive material, that is then enclosed in a structure that is made of a conductive material. You could simply wrap a cardboard box in several layers of aluminum foil and make a aluminum foil Faraday cage. Or you could go really big and put cardboard boxes inside of a large metal shipping container to make a shipping container Faraday cage.

A Faraday shield could be small, enclosing only one item. Or, you could build a mid-sized one for each room. Maybe a larger one for your garage. Let’s take a look at three simple Faraday cage options.

3 Simple Faraday Cage Options

Metal Trash Can Faraday Cage

First let’s make a simple Faraday cage out of a standard metal trash can. I stopped by the local big box hardware store and bought a 31 gallon metal trash can and a slightly smaller 20 gallon plastic trash can. I made sure the height and diameter were similar, with the plastic can being just small enough to fit easily into the metal can with the metal lid fitting snugly. I had to do a little bit of prepper engineering by removing plastic handles so I could insert the whole plastic trash can inside the metal trash can. Both lids close correctly. It is really important to have a tight seal of the outside aluminum can.

I’ve seen several sites that use cardboard or carpet pieces to make similar Faraday cages. But I really think that the ease of a second plastic trash can is the way to go.

I made a Instructable that walks through the whole creation process.

Simple Faraday Cage

Instructable - Simple Faraday Cage

This will hold a lot of stuff and protect electronics from EMP. But will also a nice portable Faraday cage.

Ammo Can Faraday Cage

Second we can build an ammo can Faraday cage. One thing about the military is that they have some really cool containers that are made to last. I didn’t realize while I was in the Army but all of the important equipment like night vision goggles, special weapon sights and shoulder-fired anti-tank weapons had custom containers. They were made of aluminum with cut out foam inside to ensure things wouldn’t move. But now I know they were also pretty simple Faraday cages. Military ammo cans are inexpensive and easy to find.

Here are a few links to help you make your own:

Faraday Bags

Lastly Amazon has some pretty cool Faraday bags for sale. There are some inexpensive Faraday bags that basically look like really thick static bags which computer parts are shipped in. Also there is a really nice duffle bag that is specially lined to protect against EMP attacks.


Once you know how to make a simple Faraday cage, it really isn’t too hard to build your own. I think it would be great to see some that other people have built. Leave comments or send me an email and I will add them to this post.

By |2018-10-26T10:05:35+00:00June 9th, 2017|Books, EMP, Faraday Cage|6 Comments


  1. John May 5, 2018 at 5:45 pm - Reply

    The metal trash can is a good start to a Faraday cage. Unfortunately, there is “too much gap” between the lid and the can, so higher frequency energy can leak through. The fix is to tape all the way around the joint with conductive tape (aluminum tape a few aisles over from the trash cans in the big box store)

    The ammo can also is problematical. There is a rubber gasket which insulates the lid from the bottom, making it not a Faraday cage at all (by definition, a Faraday cage COMPLETELY surrounds the interior with ONE CONTINUOUS CONDUCTOR). This is harder to fix. If you replace the gasket with a conductive one, that might help. If you remove it and figure out a way to force the top to contact the bottom firmly, that might help. Once you get conduction between the top and the bottom all the way around, I’d use the metal tape all the way around in case there are any gaps which energy can sneak through.

    Be careful of EMP “bags”, particularly from Amazon which on occasion has not been accurate in the description of products. The “duffle bag” ones can be pretty good, but they cost. The “zip lock bags” are limited in effectiveness. I’ve seen a few which appear like they COULD be adequate, but the single layer mylar ones won’t keep out EMP level energy. If you must use those, wrap the electronics in something non-conductive, put it in the bag, wrap that bag in aluminum foil and then put that into a bigger bag (mostly to protect the aluminum foil from being penetrated).

    • Marc May 11, 2018 at 8:15 am - Reply

      Hey John, take a look at Michael Faraday’s original faraday cage designs. One continuous conductor is not required. Often industrial faraday cages are mesh that has intermediate conductivity to allow airflow.

      Totally agree with the aluminum tape around the lid of the aluminum trash can and the ammo can.

      But on the ammo can I think it is actually easier to keep the rubber gasket in place. This way you have a water tight container. Instead I would remove a little bit of the paint on the exterior of the ammo can on both the lid and body of the can. Then put the aluminum tape completely around the lid. This will create the conductivity required and also seal the bare metal so that you don’t have rust issues.

      Thanks for commenting.

  2. Illini Warrior May 5, 2018 at 7:52 pm - Reply

    that DIY cord lid handle won’t pass muster – you can’t have holes drilled in that outer can skin with only rope filling the penetration – micro pinholes aren’t allowed ….

    • Marc May 11, 2018 at 8:23 am - Reply

      Woot! someone who actually clicked through to the Instructable! Or wait.. maybe you came through from Instructables. 🙂

      But actually having holes in the top of the plastic interior trash can is just fine. The idea of the interior container is to be in insulator so that the items that you are trying to protect to not touch the exterior metal.

      Do a search for industrial faraday cages and look at the images. Fact is that you could have an all metal shipping container and simply putting items on a wooded pallet would protect them from an EMP blast.

  3. J. Broderick May 6, 2018 at 8:20 am - Reply

    These are great ideas. Question: It seems unlikely we would know when an EMP will strike, so would these protective shields help after-the-fact? Thanks

    • Marc May 11, 2018 at 8:25 am - Reply

      No. If there was an EMP attack, faraday cages would not help after the fact. The electronics would already be damaged.

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