There are a lot of reasons to build a Faraday cage. One of those reasons is to protect your electronics against an EMP attack. Whether you are a prepper or someone that wants to be prepared, you can now build your own Faraday cage from home.
And that is not all.
In this article, I am going to cover the science on how this cage works, the reasons as to why you would want to bother building such a cage, how to create one for very cheap and also what to put in them.
The science behind the Faraday cage
A Faraday cage is a container that has a protective layer consisting of a metal that protects the inside of the container against electromagnetic interference.
Electromagnetic waves also come in a vast spectrum of light. It ranges from a high frequency with a lower wavelength up to a low frequency with a higher wavelength. Electromagnetic waves will cover Y rays, X rays, UV rays, visible light rays, infrared, microwaves, short radio waves and also long radio waves. The image below will show you this spectrum.
The protective layer should be made from metal that has conductive properties. The concept of the cage was invented by a British scientist Michael Faraday who conducted studies on electromagnetism and geochemistry.
Charles-Augustin de Coulomb is also a brilliant scientist who contributed significantly to the development behind the science used by Faraday cages. Here are some concepts that you need to understand.
- The net electrical force inside a conductor should always reach an equilibrium which means the net force must reach zero.
- The positive and negative charges inside a conductor must be as far away from each other as possible at equilibrium.
So how do these concepts relate to Faraday cages?
It is important to note that the conductor use will already be in a state of equilibrium which means that it will have the same number of the positive and negative charges inside. These charges are also equally distributed throughout the conductor.
Once a radio wave hits the conductor, it will push all of the positive charges away from the direction of the wave. Now the positive charges will be located on the furthermost point away from the direction of the external wave while the negative charges will be located at the closest point from the external charge.
It is important to note that the external wave or field is oriented in a positive to a negative direction. While the positive charges are pushed away, and the negative charges are opposite the positive charges, they will create their own field.
The field created by the Faraday cage will move in the opposite direction of the external field and will cancel out the external field because it must reach equilibrium. Now, where does the Faraday principle come into play? It becomes beneficial because the charge will redistribute around the surface of the cage and will not cross the surface barrier into the box. This means that anything that you put into the box will be affected by any external EMP sources.
Faraday cage uses
Why would you even bother building your own Faraday cage? There are many reasons why. It is to protect your electronics from any outside electromagnetic disturbances that can cause either damage, steal data or track the goods placed inside. Let’s start with one of the most feared ones, and that is electromagnetic radiation.
1. Nuclear electromagnetic pulse
This type of EMP originates from the detonation of a nuclear bomb in the atmosphere which can create electromagnetic radiation. This phenomenon will cause massive damage to all electrical goods in the area affected caused by voltage surges.
To have this type of effect from a nuclear explosion, you need to detonate the bomb at high altitudes. An explosion at an altitude of between 20 and 40 km will paralyze most of the US. The earth’s magnetic field will also deflect the electrons from the blast in a sideways manner covering a larger area.
The most common cause of this type of attack might come from a terrorist attack or world war 3. North Korea was or is capable of launching such an attack which could devastate the infrastructure of an entire country.
2. Solar flare (geomagnetic storm)
A sun storm (also called solar flare) can cause a geomagnetic storm on this planet which will also affect the whole power grid. One of the most significant solar flares happened during 1859, so they are not that uncommon.
During that time, the solar storm was so strong that they damaged telegraph machines. The solar particles from a solar flare are too much for today’s transformers which are used in the electrical grid and most electrical equipment.
During and after such a storm you will also notice auroras which are also common at both of our planet’s poles.
3. Blocking cell phone signals
There are many reasons why you would want to block cell phone signals. The most common reason is because you might suspect someone to track your position and activity.
It is also important to note that Faraday boxes come in different sizes. There are also small carryable cases in which you can place your cell phone to block any incoming or outgoing signals.
The problem with cell phones is that our lives are on these devices. Today is much worse than a couple of years ago because we currently have more personal information on these devices that can be used against us.
The potential aftermath of an EMP strike
Whether the EMP strike will come from nuclear or solar flares, the effects will be catastrophic. Just imagine what will happen if our whole power grid is disabled and damages. The damage is also not limited to the power grid alone as individual electrical devices will also suffer.
1. Disabled transportation infrastructure
Your car will be disabled because it also makes use of electrical units that are responsible for the sparks in the engine and for starting your vehicle. Busses, delivery trucks, and airplanes will not be able to transport any goods from production sources to retailers.
This will result in food shortage after a couple of days. Along with this, gasoline won’t be transported if you choose to use it for something else. As a final thought, I would like to conclude that you will be a sitting duck and won’t be able to move anywhere.
2. Collapsing telecommunications
You will not be able to use your cell phone, and satellites might not be able to send any signals to earth. You won’t be able to use the internet and to receive any critical information on news events.
There will be a lot of confusion, and you won’t be able to send any distress signals for when you need any help. If you could have the ability to use a communications platform, then you must remember that the network line will also be congested.
3. Economic collapse
First of all, you will not be able to withdraw cash and can pose as a problem because most of us are reliant on doing everything through wire transactions.
Banking sectors will collapse, and currencies will fall. No trading in the financial market will be present. There is also the possibility that your bank account could get wiped out because all of the data could get lost. Some banks are now more reliant on storing information digitally instead of on paper.
4. Food preservation and transport
If you have meat stored in your fridges, then you must consume it as fast as possible because refrigerators are reliant on power. All of the food manufacturing processes will halt.
As mentioned before, there will also be the problem of the transportation of fresh food to your area. You might be in luck if there are any local food producers from where you can get some new supplies.
5. Health services
Another crucial sector is health providers such as hospitals. All of the machines used to keep people alive will falter and result in many deaths.
While some machines are used to keep people, alive others are used to do emergency and lifesaving surgeries. Transportation of medicine will also become a problem.
Making the Faraday cage
This process is what you have been waiting for this whole time. You have the option to buy a Faraday, but it is much easier and cheaper to make your own.
1. The materials that you will need
The first choice that you must make is going to be the size of the cage. Most people create an image of a large cage in their mind when they hear the term Faraday cage which overcomplicates the process.
Instead, you can make a Faraday cage out of almost any type of container that is lying in your backyard. You can use small containers such as a cookie box up to a larger container such as a trashcan.
2. Making a Faraday cage from a box
You can either use a wooden box or one made from cardboard. Take the aluminum foil and cover both the inside and outside of the box. Then you should take the foil and cover the bottom and top side of the lid as well.
Try to add at least 2-3 layers. The more, the better but you should not overdo it because the lid should fit perfectly on the box and not create any leakage. If you can wrap presents, then this should be easy enough.
Once you have covered the box and the lid, you can wrap your electrical appliances with the cloth or foam wrap. Place the wrapped electrical items inside the box and then put the lid on. Once the lid is on, you need to seal it with the copper foil tape to prevent any leakage.
3. Using a garbage can as a Faraday Cage
A garbage can is also useful especially if you have a lot of electrical items to protect (or large ones for that matter). The very first thing you need to do is to seal all of the seams that connect the sheets of metal with copper foil tape. Do this on the inside and also the outside. You should also look for holes for potential leakage.
Once everything is sealed, you now need to cover the base of the garbage can with a cardboard box. You can measure and then cut out a circle to then place inside the can. You should also add more cardboard to the inside area around the can.
Next, you should make sure to cover the inside and the outside area of the lid with tinfoil as well. Wrap the electronic devices with foam wrap and place them inside the can. Place the lid on top and make sure to seal it with the copper foil tape.
4. Testing the cage
This part of testing is very crucial and also very simple to do. You can start by placing a radio inside of the cage and then cover it and seal it. If the radio has lost its signal and generates a buzzing sound, then it has past the test.
You can also place your iPhone inside the cage and then try to call to your phone with someone elses phone. If it does not ring then your cage is successful. But what do you do when it fails?
The answer is straightforward. You need to look for leakages and make sure to seal them. You also have the option to add another layer of aluminum foil to add extra safety.
Items that you can store inside
All of the essential electrical items should be placed inside the cage. You can start by cell phone and charger which is the most critical items that you will need.
You can also add the following items to the list:
- Radios will allow you to listen to any updates and essential news if available.
- a Laptop with charger. It will also help if you have a spare laptop with a charger and a wifi adapter.
- USB drive with your most important information. This information can include your banking information and all of the associated passwords,
- Solar adapters and chargers. If you can get your hands on a small solar charger, then I will highly recommend it. With this device, you will be able to charge your phone and all of your appliances.
- Flashlights can also be useful to give you some light during the dark.
- Rechargeable batteries with their accompanying chargers. Make sure that you choose the right battery size for the appliances that you also want to store. You should also make sure that the charger is compatible with your solar charger.
- If you are experienced with cars, you can keep spare electrical parts inside of the cage. This plan will allow you to replace the broken parts with new ones after an EMP attack.
As you can see it is not that hard to build a Faraday cage. I also hope that this information has given you enough reason to do so. Please leave a comment below if you have any questions and also recommendations.
victor lavaza says
Hello Lewis, awesome article you have here. Many thanks for the information you’ve shared. I am a prepper myself and I like preventing problems from happening if and when I can and also making plans so as to mitigate problems if, as and when they come my way.
I am going to make a Faraday cage using a box with your article as guidance. I doubt I will run in difficulties as you have explicitly elaborated the steps. However in the event am having any trouble, I will get back to you with queries.
James Underwood says
Great article on how to build a Faraday cage. You definitley have a good understanding of how it works and why someone would need one. Its one of those things you hope you never need to use.
I see a lot of people recommending using a microwave as a Faraday cage, I’m assuming for small items. What do you think about that? Does a microwave pass the test?
Also, what about grounding. Does a Farady cage need to be grounded?
Lewis Miller says
A Faraday cage does not need to be grounded for it to work. Some people say that a microwave works but it all depends on the microwave as brand make their products different.
julienne murekatete says
I can’t deny it ,I was afraid while reading this post.All those electronic disturbances can result in disaster.When I go to bank and I found my bank account has zero balance or they tell me that they can’t find my name in their bank!!! It seems like a joke but It can happen .
Faraday cage has great importance in avoiding such situation and thank you for showing us how to do it on our own.
What if I decide to buy it? Is there any market for Faraday cage?
Lewis Miller says
You can buy one if you want. It depends on the cost and if you have access to a lot of aluminium or copper foil then you can just as well build your own.
Kris M. says
Thanks for the very informative article on how to build a faraday cage. I’m a little confused about the purpose of it. If there were to be a nuclear bomb that would take out our electrical grid and such…my personal devices would be useless at that point, wouldn’t they? Can you elaborate on why we should use these faraday cages to protect devices that couldn’t be used anyway?
Lewis Miller says
If an EMP attack goes off all of the electrical units will be fried. Even though the electrical grid will be useless, some of your electrical appliances will not be. Just make sure that you can recharge these units without being reliant on the grid. You can use a small solar panel which is also reusable.
Hi Lewis,I heard about Faraday cage, but never tried building it myself. It’s so great that you can store so many important things in it. I appreciate your detailed explanation and I like the v. clips you put also. When I see how it’s done visually it looks much easier to do it myself. Important files and devices should be protected and this seems as a great way to accomplish that.After reading your article, I feel motivated to try this. That would really help I think. I will consider it.Best regards,Strahinja
I have built a 3m x 3m shed with a a sheet metal roof & I have lined the 4 walls,roof & floor(6 sides) with a double layer of chicken wire stitched together with copper wire stripped bare from old electrical cables with outdated colour coding(Red & Black).I will be soldering that at several points & I have weaved extra copper wire through the whole of the 6 sides & connected this to 4 electrical earth rods at the four corners knocked into the ground.
Then I have covered the 6 sides with Aluminium foil loft insulation rolls=Superquilt.I bought some copper tape with conductive adhesive from Amazon(Used on Guitar pick ups & recommended by Arthur T.Bradley.Ph.D.)to connect the 6 sides.
The difficult part is the double doors that open out.I raised the floor chicken wire by 6″ by the door & the floor frame will be covered in Aluminium tape facing out to the door.I plan to cover the inside of the door with either Aluminium tape & chicken wire x 2 or Supperquilt & chicken wire x 2.
The tricky bit is ensuring an overlap of foil & chicken wire that covers the gaps around the doors & between them.There must be 100% contact.
Hopefully the chickenwire will also keep out the rats as well which increases the value of the project.& I will add a wooden decking floor on top of the foil & chicken wire & wooden planks over the inner walls to isolate everything from the cage.
At least it will provide EMF shielding from the local radiation from cell towers/phones,cordless phones,smart meters & all the other crap they poison us with=we are on 4G already & in the UK they have started rolling out 5G=Silent warfare on Civilians.
I would think it prudent to protect electrical devices that we may need after a “scenario”=Geiger counter,blood glucose test machines,torches12V LED car lights,My Laptop with Geiger graph software to measure radiation,walkie talkies,radios,12V Ham radios, laser sights,12V fans & water pumps,car & domestic batteries,Binoculars with battery powered Gyroscope stabilisers,Portable Solar panels & its equipment.Electrical Generator,etc…………..Where Possible I wil follow the principle of “Doubling up”….that is smaller items will be stored in a smaller Faraday Cage within my shed & VERY important items stored within a Faraday Cage within a Faraday Cage within my shed.Better safe than sorry=Be Prepared.Even if the grid is out ALL the above can be protected & “should” work AFTER the EMP effect dies off in 6 months+???
NB- if we do not seal the CONTACT points around a box or galvinised bin,etc the cage wil not work properly-think of it as sound or cold seeping through the gaps.Doubling/tripling is good policy/insurance.For only a little bit more work.
IF I was in the USA I would buy Dr Bradleys car EMP proctector & his other EMP protectors(House)………It costs too much in postage & customs to send to the UK…………Everyone will need transport,unless you just use a Bicycle?Or Horse?
Hope this helps?Let me know if I forgot anything?Or you have any advice on how to improve my set up?Please do give it,Thank you.
What about air duct could you use it . Just wondering!!
I think air duct can work in blocking electromagnetic waves. Just make sure it is made from the right material
What about a poured concrete basement room that has typical rebar grid wire in the concrete and the ceiling(porch above) and the floor are all poured reinforced concrete etc. Already, I know a cell phone fails to work in there. Many cages we see pics of are not sealed 100% closed containers but rather look like a screen or bird cage affair??? only opening is 1 wooden door which could be lined with Alum sheets on inside – sound correct?
I think that might work. You just need to consider the cost of building something like that. If you want to protect valuables such as electronics or phones, then you can just as well use a smaller box.