EMP 101: Part IV—Faraday Cages

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Faraday Cages
By Kellene Bishop

Faraday Cage c/o jeddaniels.com

We’ve established that an EMP incident will fry all electronics.  This occurs whether or not they are plugged in or turned on. This also affects automobiles, batteries, computers, medical equipment, etc.  Needless to say, in such an instance, life as we know it will change dramatically.   Even more distressing is the fact that the strike of an EMP is not likely to give any warning. You don’t see it. You don’t feel it. You are simply left with the sudden consequences and whatever preparedness you have on hand.  So, other than your preparedness supplies, your new best friend may be a Faraday cage. In fact, with the knowledge of the protection that a Faraday cage can provide you, you may be able to enjoy nearly as comfortable a lifestyle as you did prior to any electromagnetic pulse.

While being mentally prepared to live in the Stone Age may be helpful, it’s not necessary. Aren’t you glad?

First of all, allow me to dispel some myths about Faraday cages—and boy, howdy, there are a LOT of them.

• Whether or not your electronics are plugged in, how long of an antenna you’ve got on something, what voltage it is, or whether or not they operate with batteries—all non-protected electronics will be affected by an EMP. 
• Batteries will be affected, usually in the form of “shorting” as well.
• Electronic phone systems will also be damaged. 
• Surge protectors are useless in the event of an EMP exposure. 
• Just because your car has rubber tires, it will not be impervious to the effects of an EMP.  Rubber containers are insufficient protection against an EMP.
• And oh yeah—yes, your Faraday cages DO need to be grounded.  If it’s NOT grounded, then the Faraday cage merely becomes a reflector or an amplifier.
• Yes, a microwave can act as a Faraday cage, but why in the world would you want to use it for that?  That’s just silly when you can make one simply.
• Faraday cages do not have to be solid, thus the name “cage” instead of the oft misused term—“box.”  In fact, many of them that you can build yourself or will see on the internet will resemble a bird cage or a very finely meshed chicken coop wire. 
  

  Copper Mesh photo c/o twpinc.com

• Also, contrary to what you may see on the internet, a sheet of foil on a box will not protect you.  It’s not thick enough to withstand the pulse. However, you CAN protect your items if they are buried a couple of feet underground in every direction (up and sideways.)
• Last, but not least, a car is NOT a Faraday cage sufficient to withstand an EMP incident. It has some similar components, yes.  Most cars made today consist of fiberglass and disjointed parts, not a continuous metal material.  In addition to that, they are on tires.  Tires on a car do NOT serve as grounding.  Folks are simply getting an EMP strike confused with a lightening strike.  Now, IF you had an old fashioned car that was made of metal, that had its tires removed, that was also attached to an Iron or copper pole and that was ALSO on dirt—not  gravel—then  yes, you may have a car that doubles as a Faraday cage. (Kind of like the old clunker my dad has out in his “back forty.”  
• The cages do not have to be solid, but they do have to be constructed continuously without gaps between the protective material.

There. Now that we’ve discredited 90% of the internet information out there, let’s continue.

Michael Farady oil, by Thomas Phillips. photo c/o commons.wikimedia.org

Faraday cages are named after Michael Faraday who invented them in 1836. They block out external electrostatic fields and electromagnetic radiation.  One mistake many people make when it comes to an EMP is to compare it to a lighting bolt.  The effects of an EMP and a direct lightening bolt are very similar, but they are not at all similar in terms of their visibility, and affect on the body. An EMP is more like a radio wave, not a visible bolt of light or electric current.   

It’s the substrate layers of the diodes and transistors that make them susceptible to a magnetic pulse attack. Electronics are made up of diodes and transistors and substrate layers. A computer, car, television, and cell phones are made up of tons of transistors. When hit with a powerful magnetic pulse, the substrate layers are destroyed. However, early 1960’s and before electronics did not use substrate layers. They used vacuum tubes.  This is why older electronics are less susceptible to damage. This is why a human or animal body will not be affected.  Yes, our bodies consist of an electric volt. But understand there’s a difference between electricity and electronics. 

I just want to reiterate this again.  It’s important that any Faraday cage that you plan to use is grounded.  It has to be grounded in order to disperse the energy. 

What you should know though is that a Faraday cage is not fool proof.  The higher the frequency of the magnetic pulse, the faster it is. This is what causes the burn out.  The cages must be grounded, continuously connecting, and the openings of them cannot be too large. Chicken coop wire would work, but only if you double or even triple layered it as the opening are too large. For a reference of opening size, look at the front of your microwave door.  It’s a small mesh.  Just a like a snake can slither its way through the right sized hole, so can an electronic wave.  

Galvanized Trash Can photo c/o housewares.hardwarestore.com

You can have an instant Faraday cage with a galvanized trash can or a large stock pot like they use in restaurants. (Be sure to clamp the lid down. Remember—continuous connection is key. Since Faraday cages are not fool proof, depending on the strength of the pulse, I would recommend burying such containers 2 feet under the ground, storing survival electrical and battery items. (Including batteries). 

An easy way to make a Faraday cage would be to acquire some 2 x 4 brass mesh sheets. (Mythbusters on the Discovery Channel did a couple of experiments using this successfully.)  Make a box frame with the 2 x 4’s and staple the brass mesh to the outside. Create a securely attached/connected access entry within the frame. Solder a ground wire to one of the corners and ground the cage.  Scrap metal and mesh wires can easily be obtained in junk yards, on E-bay, the clay modeling section of a craft store, or at your local hardware or  “farm and feed” store.  The important aspect of this to remember though is that mesh or sheet metal only shields magnetic fields if the frequency is up in the RF range. To properly stop the wave, you need some iron, steel, or some slabs of thick copper.  Most electronics are useful in the VHF/UHF/SHF range today and will need more substantial protection.  Remember when you’re browsing the internet.  Protecting against sparks is not the same as protecting against a strong magnetic pulse.  

You can make your “cage” as small or as large as you’d like.  It wouldn’t be out of the question to continuously line a basement storage room or hole in the ground with copper mesh wire and a grounding rod.

Bottom line, with an appropriately constructed Faraday cage, you can likely protect that which is inside from the electromagnetic attack of an EMP incident or solar flare, thus preserving the function of all that is contained therein.   Here is a very simple example of how Faraday cages work.  (DO NOT try this at home, please)

Note that the Peeps are put into a mesh bowl and covered with a mesh cover. They are then put in the microwave.  The one Peep that wasn’t put in the microwave met his untimely death, while the others were still intact.

For a little bit of a science lesson on the workings of a Faraday cage, check out this YouTube link. The science professor is EXCELLENT.  Note though that he does say that a car is a Faraday cage, however, I want to reiterate that it is NOT sufficient to extinguish the effects of an EMP attack. 

Photo c/o physics.umd.edu/

Be selective in what you protect. It makes no sense to protect a cell phone, for example, as the cell towers will be useless.  If it were me, I would protect radios, communication devices (such as a HAM radio), batteries and all of their respective tools, thumb drives loaded with all of my vital information, and a laptop.  Keep in mind that a Faraday cage should be your LAST concern in terms of protecting every electronic that you enjoy presently.  It’s not like if you preserve your television you’re going to have any “juice” to plug it into.  Don’t focus on a Faraday cage and its time, effort, and expense at the risk of neglecting food, water, and medical supplies. It would be better for you to read up on solar power, wind and steam energy instead.

• EMP 101: Part I–The Likelihood.
• EMP 101: Part II–The Aftermath.
• EMP 101: Part III–Prepare Medically.
• EMP 101: Part IV–Faraday Cages.
  
  Copyright 2009 Preparedness Pro & Kellene Bishop.  All rights reserved.  You are welcome to repost this information so long as it is credited to Preparedness Pro & Kellene Bishop.

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