DIY Faraday Cage

DIY-faraday-cageAs Preppers we like to think that we are pretty well prepared for most eventualities. One event that can seem daunting to prepare for is an Electro-Magnetic Pulse (EMP) event. If this type of event occurs, the vast majority of our electronic devices would be wiped out and we would lose much of our ability to communicate with others – such as cell phone, email, and ham radios, etc.

Do you keep much, if not all, of your prepper manuals on a laptop, external hard drive or tablet?  An EMP can destroy the ability of your device to function.

One way we can protect them from an EMP is by building a Faraday Cage.

What is an EMP?

In simple terms, an EMP occurs in either of two ways: (1) when a nuclear event causes Gamma Rays to be released above the atmosphere, or (2) from a natural, Coronal Mass Ejections – solar flares from the sun (as happened across the US in 1859 – melting telegraph wires, and in 1989 in which many orbiting satellites lost control and the power grid of Quebec was brought down for 9 hours).

Gamma Rays are protons with extremely high energy and these protons collide with atoms in the atmosphere. This causes high levels of electrons to become free from the atoms, thus generating an EMP. An EMP will overload the circuits in any unprotected (not hardened) electronic device rendering it completely useless (if it is still in one piece).

What is a Faraday cage and how will it protect your electronic devices?

A Faraday Cage is a structure that is made of a conductive material that allows an EMP to flow around the cage as opposed to through it. By doing this, the pulse does not go through your devices that are stored in the cage – the pulse goes around it. These cages can be extraordinarily complicated or very simple depending on the amount of time, money and resources you have at your disposal.

Almost anything could potentially be turned into a Faraday Cage providing they meet the following criteria:

  • It must be made of a conductive material
  • It must be properly grounded (also known as Earthed – basically meaning attached to a source that can absorb an unlimited amount of current without changing its level of charge. An example of this is the Earth, or the ground, hence the name!)
  • It must adequately surround anything that is going to be protected inside
  • Anything placed inside the cage must be insulated from the cage itself.

How do you make a cheap Faraday Cage?

A simple way of making your own Faraday Cage is by using a metal trash can. With a few simple adjustments, the trash can will act as a perfect shield for all your electronic devices should an EMP occur.


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Step 1 – Insulate the inside of the trash can to prevent your electronics from touching the metal. This can be done by lining the inside edges of the trash can with cardboard. An additional layer of foam can be added if you want to add some extra insulation.

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Step 2 – Prepare your electronics for placement inside the can. Another layer of protection can be added by wrapping all devices first in heavy wrapping paper, then in aluminum foil. By doing this you now have four levels of protection between each device and the sides of the cage.

Step 3 – Pack all of your devices into the cage making sure that none of them are touching any metal of the can.

Step 4 – Place another layer of cardboard and/or foam on top of all your packed electronics. (This will stop them touching the metal on the inside of the lid)

Step 5 – Place the lid on the trash can. You will need to seal the edges of the lid down with a metal foil tape to ensure it is completely sealed.

Step 6- Attach a ground wire to the outside of the cage, and the other end to either a heavy metal object (a pipe, for instance) or to a spike which is driven into the ground.  If at all practical, place the cage in the lowest, most protected part of your home (basement, etc.) for extra protection.

This is your completed Faraday Cage.

An easy way of testing to see if it is an effective shield for everything inside is to complete a simple test using a cell phone.

If you place a cell phone inside your cage and call it the phone should not ring. This is because radio waves should not be able to travel through the cage. An EMP travels in the same way as radio waves. If radio waves can travel through your Faraday Cage then it is not sealed tightly enough to stop an EMP. Double check the tape around the lid of the can is making a complete seal to prevent any weak spots and repeat the test.

If the phone does not ring – you have built an effective Faraday Cage and your devices have a better chance of surviving an EMP.

A good point to remember is to include a small solar panel, rechargeable batteries and charger in your cage so you have a means of powering your devices in the event of a total grid shutdown.

Editor’s Note:  There are naysayers with regards to the effectiveness of Faraday Cages.  The only way to truly test them is to either get hit with an EMP or to have an ultra-expensive piece of testing equipment.  We believe the science involved is sound.  We also believe in PACE – Primary, Alternate, Contingency and Emergency.  Basically having a back-up for your back-ups.  We’ve built a Faraday cage from a small steel garbage can as detailed above, and whenever we get a new piece of electronics equipment, the old piece goes into the cage.  Batteries are removed and placed in marked ziplock bags.  Our emergency prep info is included on the micro-SD cards in the phones (along with the adapters so they can be read by other devices), hard drives of the laptops and on a USB thumb drive.  Back-ups for our back-ups at no additional cost!



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