DIY Farday Cage: EMP Protection


What is a Faraday cage?

It is a device that allows you to shield electronic devices from an EMP, which will destroy unprotected items such as radios, walkie-talkies, anything with circuitry.  Simply it absorbs the charged particles and directs them into the ground like a lighting rod.  I talk more about this in my podcast on this very subject.

 

Building a Closed Faraday Cage

The difference is with this one, it is sealed and cannot be opened and closed at will, you put in what you want now, seal it and open it when you need it, not whenever you want.

Items you will need

  • A Large Roll of unpainted aluminum window screen.
  • 2×200′ boxes of Aluminum Foil & Saran Wrap (Hit up Costco/Sams Club)
  • Heavy Duty Garbage Bags
  • 1 Box Small & Large Ziploc Freezer Bags
  • 150′ Industrial Grade Duct Tape
  • 50′ Electrical Tape
  • Heavy Gauge 3 Prong Grounded Power Cord (Use old Surge Protector, Buy one or use old computer power cord)
  • 1 Pack Desiccant Silica Gel
  • Cardboard

 

 Step 1:

Get together all the items you want to protect (remember you cant just get into this whenever you want, so make sure these items are not needed daily/weekly/monthly).  Remove all batteries and store them in ziploc bags (if you leave them in the electronics they will eventually leak and destroy the item.  I would put in rechargeable batteries with the charger for whatever you are using. Try to vaccum seal all the items and then place them ziploc bags if you can, if not just try to get the air out of the ziploc bags.

Sidenote: Eneloop Batteries are some of the best ones out there, they are Low discharge, pre-charged batteries, so they lose their charge very slowly and probably will still have a decent charge when you open the case.  I use a Energizer Family recharger as well, it fits all the rechargeables i use from AAA to D

 

Step 2:

Once the items are sealed in the bags, wrap them in 3-5 layers of plastic and 3-5 layers of Aluminum foil in alternating layers, plastic wrap should be the inner and outermost layer.

 

Step 3:

Seal each wrapped item in a zip loc or garbage bag.

Step 4:

If you are using a steel garbage can remove the handles from the side of the can, spread them open and pull them off.  If its an ammo can, sand or grind the paint off of the lips of the container and lid and if the rubber gasket is till present, remove it and scrape away the remnants.

 

Step 5:

Use strip of aluminum foil to fill any gaps that may be between the seams of metal, even areas where the metal is stamped together or there is a seam there may be small gaps, fill them with aluminum foil will make sure there no gaps in the conductivity of your outer container.

 

Step 6:

You can line the inside of the can with cardboard or place the items in a cardboard/plastic bin/box

Open and place the desiccant pack(s) place in the container with the items.

 

Step 7:

Use one long unbroken strip of aluminum foil to create a conductive metal gasket (fold the foil to make it 3-5 layers thick) around the lip of the container, this will ensure a tight fitting conducting lid.

 

Step 8:

Secure the lid on the metal container and make sure its a tight seal.  If you’re using a garbage can use 2-4 small strips of duct tape to make sure the lid is secured in place, but not too much.

 

Step 9:

Wrap the whole container with at least 3 layers of foil, you can use a small amount of tap to secure the foil in place, but you want AS MUCH of the metal surface as possible exposed.

 

Step 10:

This part is more difficult, once you have it wrapped in aluminum foil you must wrap the entire thing in the aluminum screen.  According to the site i went to for this his opinion was to wrap the top and bottom first, vertical first then wrap the body horizontally.  Make sure the screen overlaps so that there arent any gaps, you can use duct tape to hold it in place

 

Step 11:

Get A Piece of Copper Wire long enough to reach a grounding rod that you have driven into the ground outside.  Some say you dont need a grounding rod, but I am still convinced that you do to make it work as effectively as possible.  Do NOT ground it to the grid or your house! Find an exposed section of aluminum screen near the bottom of the cage, use a protuding section of the screen.  Poke two small holes in the screen about an inch apart and feed the exposed copper wire in through one hole and back out through the next.  Then twist it around itself to hold it in place.  Feed this to the Grounding Rod and Clamp it to the rod.

 

Notes:

The Post previously mentioned using a electrical cord and plugging the ground into a wall socket.  This was brought to my attention by a reader named “Ron”.  Upon further investigation I believe that he is correct.  I apologize

 

 

Also Here is a neat Faraday Cage made from a Metal Cabinet bought on Craigslist.

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Comments

  1. Char South says:

    I did the same thing with a 20 foot storage container .
    Mine is lined with 1′ stryfoam 4×8 panels (no foil) taped seams has a thick rubber gasket on doors…(sea proofed)
    question/thought…I think I should put a grounding rod as use on electric panels and connectit to the container……????

  2. The whole thing about “grounding” a Faraday cage is wrong. By connecting to your grounding system in your home, you have just connected your Faraday cage to the electrical grid coming into your home. This grid will be super energized if we would get hit with an EMP. Thereby directing all that energy into your cage set-up. No ground is needed. The idea is to have a covering that will allow the energies to pass around the outside of the container without penetrating the interior. The less energies you have to contend with, the better. Grounding it to the electrical grid is like placing a lightening rod on it. This is what my own research has shown me.

    • Great Northern Prepper says:

      Upon Further Review, I think you are right Ron. I appreciate the heads up and have since edited the post to reflect that. Thanks for keeping me on my toes!

      • You’re welcome. This is how we all learn. Myself included.

        • Great Northern Prepper says:

          I have been searching for awhile for actual scientific studies and tests on these homemade systems, however i have not been able to find them. If you know of any place let me know

  3. Here is the instructable for a Faraday cage that is easy to make (modify) and will look good in the house. It also doubles as a file cabinet

    http://www.instructables.com/id/Stylish-Two-Drawer-Faraday-Cage/?ALLSTEPS

  4. Everyone should re-think the idea of grounding a Faraday cage to your house’s electrical ground system. An EMP will develop an extremely large current in the power grid and effectively saturate the ground in your electrical system during the time when your Faraday cage needs that path. Better to ground it directly to a separate earth ground rod or a cold water pipe. Just check the net’s pro & cons of earth ground vs power ground. Hope this helps.

    • Great Northern Prepper says:

      Thanks for the tips, I will look into them. Ive actually moved away from actually thinking these will be of any help whatsoever in a true CME (or like) event. I have been meaning to update this post with my new thoughts.

  5. That is some serious EMP protection. I use aluminum foil and nested cardboard boxes to create the layers of shielding, all the boxes have at least 2 layers and the most I have is 4 for the one holding a spare laptop. I used to ground all mine, but disconnected them based on the info here:
    http://www.futurescience.com/emp/emp-grounding.html

    I think there’s a semi-common belief when discussing EMP that either the devices in the cage (of whatever construction) are protected, or they aren’t. Or “good cage = device is safe” versus “bad cage = device will be destroyed”. From the information I’ve read, it’s a lot grayer than that. Each device has it’s own failure threshold, and the cage(s) don’t completely block the E1 pulse, but just attenuate it. The stronger the pulse, the more attenuation will be needed to keep the damage below the failure threshold of the devices inside. The better the cage(s), the more attenuation. More sensitive devices in the same cage could be affected, while less sensitive ones survived with little or no damage. Like a bomb shelter for protecting people from nuclear radiation, there are levels of protection – but none are truly “radiation proof”. Just my .02

  6. Bob in Montana says:

    The metalized mylar bags that are used for antistatic storage of electronics work great for EMP protection, AND they are super cheap. You can buy them online from ULINE. Use two if you are paranoid, tape shut (or buy the ziploc type), and store in another metal container, like a metal trash can, cookie tin, or file cabinet. This will give you 60dB-80dB of attenuation against EMP. Grounding correctly is difficult (requires wide copper braid), and is unnecessary if your package is properly closed.

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