15 Things You Think You Know About Faraday Cages But You Don’t

By Anne January 13, 2017 14:40

15 Things You Think You Know About Faraday Cages But You Don’t

This article takes into consideration only the effects of a nuclear EMP, not a solar flare. A solar flare would only affect any electronics connected to the grid.

#1. Will a microwave work as a Faraday cage?

No. If an EMP strikes, you will notice that all your electronic devices that you stored in a microwave oven will be rendered useless. The microwave is not a Faraday cage.

#2. Will a refrigerator work as a Faraday cage?

No, most refrigerators do not work as a Faraday cage. I tested mine, and it’s definitely not a Faraday cage.

#3. If I keep a backup mobile phone in my Faraday cage, will it work when I need it?

Yes, your phone will work perfectly. However, it will be rendered almost useless because the network will not be functional. The only form of communication after an EMP will be the radio. Click here to find out what radio you should keep in your Faraday cage. 

#4. Do I need to store batteries in a Faraday cage?

No. They will continue to work regardless and will just take up space in your Faraday cage. Here are the best batteries for survival situations.

#5. Do Faraday cages need grounding?


#6. Do I need to keep my solar panels in a Faraday cage?

No. The only part of the system you have to worry about is your solar panel inverter. Don’t worry about your solar panels; they will be fine. It’s best to buy an extra inverter and keep it in your Faraday cage so you can replace the useless one after the EMP.

#7. If I wrap electronic devices in heavy duty aluminum foil, will that work?

No. But if you wrap the cardboard box in which you bought them in heavy duty aluminum foil, this would be an effective Faraday cage. Here are the step-by-step instructions.

#8. Will flashlights continue to function after an EMP Strike?

Some flashlights will continue to function, and some will burn out. It all depends on the power and distance from the blast.

#9. Is a shipping container a Faraday cage?

Yes, but just remember that you can’t just put the electronic devices directly in contact with the metal. Some people board the interior of the container with wooden panels.

#10. Can I use this shipping container as a “Faraday garage” for my car?

Yes, you can definitely do that. Most cars fit in a standard shipping container, but just to make sure, go ahead and take the measurements before buying a shipping container.

#11. If you turn off your devices, will they be EMP-proof?


#12. Are airplanes Faraday cages?

No. Planes operate on the basic principles of lift and thrust, so they will become more or less gliders. They will be very difficult to control and most of them will fall from the sky and crash.

#13. How do I test an object to see if it will work as a Faraday cage?

You can test any device that you think might work as a Faraday cage with a radio. Simply turn on the radio and place it inside the device. If the radio is still receiving a signal, then it’s not a Faraday cage. If you don’t have a radio, you can use a mobile phone, but the results won’t be 100% accurate in the sense that if your mobile phone still rings, then it’s definitely not a Faraday cage, but if it does not, you can’t really be sure. You need to test it with a radio to be 100% sure you have a Faraday cage.

#14. Can you EMP-proof a car?

emp carYou could build a Faraday cage, but this would mean that you will either never use your car or will need to buy a new one. I’ve seen some pictures online of people wrapping them in aluminum, but as I said previously, it’s pointless.

Instead of making your car EMP-proof, I think you would be better off buying an old, cheap car that has an electric system that is a lot less vulnerable. Here are the top 10 EMP proof vehicles.

#15. Will a galvanized steel trash can make a good Faraday cage?

Yes, but the can has to close perfectly, and you will have to line the walls with cardboard.

You may also like:

You Will Not Survive an EMP Strike Without This

The Only Way To Get Antibiotics When SHTF (Video)

Where Not To Be During an EMP

7 Actions to Take Immediately Following an EMP Strike

9 Places Where You Could Recharge Your Electronics After An EMP


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By Anne January 13, 2017 14:40
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  1. Sam6 January 13, 16:17

    I was thinking of buying a metal garbage can and lining it with flex seal a rubber sealant. Would that work in a Faraday cage?

    Reply to this comment
    • dougnicholson January 13, 17:27

      As long as the top of the can makes perfect contact with the rim, yes. The FlexSeal would take the place of the cardboard mentioned in question 15.

      Reply to this comment
    • JDC January 13, 18:05

      You could do that, but it would be the expensive way. The most important thing is to ensure that nothing you are storing is in direct contact with the metal inside, and that the lid is fully seated. I use a slightly smaller round plastic trash can inside the metal can. You could even leave items in their original cardboard boxes, though I might check to ensure no metal staples in the box.

      Reply to this comment
  2. bugjuice January 13, 17:15

    If I put a metal roof and metal siding on my house, what else do I need to do to make it EMP proof?

    Reply to this comment
    • BillH January 14, 17:08

      Unfortunately, to make a proper Faraday cage, it has to conduct on all sides. So it would need a metal floor. Also, it is critical that there are no seam gaps, as they actually act as antennas to draw the EMP into your cage. The entire surface has to conduct with no breaks so that the currents induced on the surface of the cage are free to exactly match the EMP wave.

      Reply to this comment
      • CapitalistPig January 16, 22:40

        My man camp house I bought has a metal roof,walls and a metal frame and studs with the interior being a plywood floor and sheet rock walls. I’ve tried to pick up my Wi-Fi outside and its not possible. Could I be protected from EMP?

        Reply to this comment
        • BillH February 23, 02:53

          Not likely. Floor that doesn’t conduct, windows that don’t conduct, and any seams that don’t conduct are issues. It might help protect from EMP some from blocking the waves, but that does not constitute a Faraday Cage.

          Reply to this comment
  3. Don January 13, 17:37

    Will my very heavy Browning gun safe make a suitable faraday cage?

    Reply to this comment
  4. Sertbro January 13, 17:46

    Just a quick Thank you for providing the many tips and pointers. It’s always better to obtain knowledge and devices, then to wish you did if all hell happens.

    Reply to this comment
  5. Hamgeneral January 13, 18:20

    YES absolutely, the faraday cage needs to be grounded!!!

    Reply to this comment
    • Fc January 13, 19:27

      I used to work in communications in the USAF. Our faraday cage was grounded.

      Reply to this comment
      • Rod January 13, 22:06

        I am involved in EMP preparedness and grounding can be a very tricky thing with shielded containers. If the ground wire/strap is too long it can actually become a very good antenna for the pulse. Since the pulses are in the microwave range, you can see that the connection is going to have to be very short to be effective, hence not having things grounded might be better for the civilian. I also have grounded containers but the grounding schemes for those are very elaborate and not easily accomplished by the normal DIY’er.

        Reply to this comment
      • SailorSam January 13, 22:18

        The larger the cage, the larger the cable needs to be and the deeper the ground. You will need to dissipate a lot of current.. The closer to the EMP the stronger the field, the more current generated.

        For US Navy SatComm tech.

        Reply to this comment
      • BillH January 14, 17:13

        If the primary objective of a Faraday cage is to prevent leakage of information out of the cage (a very common military need), then grounding is a good idea. But the Faraday principle does not require grounding, only an unbroken conductive surface. Grounding causes the currents induced by the EMP to NOT mimic the wave correctly. Grounding uses a different principle to provide protection — bleeding all of the power into the ground. Which is very different from, and somewhat inconsistent with, the way a Faraday cage works. See also Rod’s remarks below, which is another way of looking at it.

        Reply to this comment
  6. Outlaw Josey Wales January 13, 19:38

    How about computer anti-static bags? Logically I think they should work but you’d probably need to wrap them around the devices a few times. I work for a computer company so they are literally everywhere and free to take after they’ve been used.

    Reply to this comment
  7. don January 13, 20:30

    What do you recommend for a reliable Walkie Talkie, a CB, and a HAM radio?

    Reply to this comment
  8. N. Tesla January 13, 23:56

    Why don’t airplanes fall from the sky when hit by lightning?

    Reply to this comment
    • BillH January 15, 01:47

      An airplane is, to a significant degree, a Faraday cage. It has a conductive surface. However, there are sizable gaps in that conductive surface. Certainly the windows. And the doors may not be designed to allow conduction all around the edge with the adjacent surface of the plane. These problems can be solved and are solved for Air Force One, for example. But not for private aircraft.

      A lightning bolt will be conducted around the windows and doors and not enter the plane, as it is seeking the best conductive road to ground. But an EMP wave will enter through the openings, as it is a wave traveling in a straight line from its inception. It is not seeking ground any more than any radio wave is seeking ground.

      Reply to this comment
  9. Dave O January 14, 02:03

    What about army surplus ammo canisters, they are metal and close very secure, also come in many different sizes.

    Reply to this comment
    • dougnicholson January 14, 02:22

      The link in tip #7 discusses this.

      Reply to this comment
    • BillH January 15, 01:55

      Unfortunately, the info in the link from #7 above is incorrect. An ammo can does not normally have a conductive connection between the can and the lid all the way around. Which is a requirement. The entire surface must be conductive, with no non-conductive seams. Conductive tape all around the lid would help, but only if the paint was removed from the surface where the tape sticks to the lid and the sides. The only real alternative to make it work correctly would be to remove the rubber gasket and replace it with a conductive gasket.

      So the basic answer is no.

      Reply to this comment
  10. RayD January 14, 03:02

    Some good information here, but a few that are incorrect. Faraday cages and shielding must consider the frequency they are protecting against. High frequency signals are protected just fine with aluminum (or copper or silver). Seams in the seal are leakage paths. Low frequency can couple through aluminum magnetically despite this and need a ferritic shield (nickel, iron, or steel). Your best bet is an aluminized shield within a steel container, i.e. a metallized plastic bag inside a gun safe. Note that the seals on the gun safe can allow leakage, however. This is what probably killed your refrigerator idea. Aluminum or copper tape on the seals can solve this. Also, grounding is NOT required with a good Faraday shield. (PhD Electrical Engineering)

    Reply to this comment
  11. Ron January 14, 05:04

    Does a Faraday cage need to be grounded at the bottom? Is the EMP line of sight and will not reflect from below the burst?

    Why would aluminum not work as shielding?

    One of you commenters said you need to ground the cage. You said you do not need to ground it. Which is correct?

    Reply to this comment
    • BillH January 15, 02:05

      Does not need grounded. See comments by myself and others. EMP is line of sight. It will not travel through a hill or mountain or over the horizon. Aluminum will work fine as shielding for high frequencies, which is the main concern from EMP.

      Reply to this comment
  12. RadD January 14, 07:48

    A Faraday cage does not need to be grounded. Grounding provides a discharge path for the Faraday cage, but neither helps or hurts the items protected inside (unless the internal item is touching the cage at more than one point). Reflections occur from everything, creating both constructive (hot spots) and destructive (null spots) interference patterns.

    Electromagnetic radiation is attenuated by distance and material (shielding) in the path. So it is more attenuated when not a direct line of sight, but is still present at a lower power level.

    Electromagnetic radiation has both an E-field (electric) and an H-field (magnetic) component. E-field dominates at higher frequencies, H-field at lower. Aluminum works fine for higher frequencies, steel for lower frequencies. The item inside the cage can be in contact with the cage, but only at a single point. Otherwise, a voltage divider is created and part of the energy flashes through the device you are protecting.

    Reply to this comment
  13. MKS January 14, 10:40

    More self proclaimed experts who don’t learn anything. At the very least read MIL-STD-464 and 188.

    Reply to this comment
    • BillH January 14, 17:50

      Um, MIL-STD-464 is related to electronic safety. MIL-STD-188 is related to electronic communication standards. Neither addresses EMP at all, except by reference. MIL-STD-2169 is the EMP standard, and it is classified. You negative attitude toward your fellow bloggers appears without foundation.

      Reply to this comment
  14. Samp January 14, 12:41

    There are few absolutes when discussing EMP and things used to protect devices from its effects. Some of your 15 points are not necessarily true. There are some very good videos out there that are made by SCIENTISTS using SCIENTIFIC TESTING METHODS that put EMP into perspective. I encourage folks to do more research on the topic and not rely on this article for direction.

    Reply to this comment
  15. steven January 16, 19:28

    and right there show this tech is trash and we need to get back to the old .not tech shit that will soon fry .grr

    Reply to this comment
    • Rod January 16, 21:31

      While I sympathize with your sentiments, having been involved in EMP preps shows me the downfall of this idea. Yes, the equipment would most probably survive, but it is also extremely power inefficient, which would require a larger power source (genset, since no commercial power available) which would also require more fuel, which will be hard to come by since many of the pumps would no longer function. Best is shielded solid state with a smaller shielded genset and as much fuel as you can get your hands on, yet still keep viable.

      Reply to this comment
  16. KP January 16, 22:16

    If I store a spare computer for a 1992 Ford Ranger (pre-programmed) in a Faraday cage will my truck run after an EMP?

    Reply to this comment
    • Rod January 16, 22:32

      Best answer I can give is “Maybe” because when you are talking about EMP there are as many variables as there are when you deal with lightning. If you are right under the burst (assuming nuclear device) then you will probably lose the alternator and starting motor and other things with coils of wire. Farther away from ground zero the effects diminish. It also depends on the strength of the pluse. There is also a school of thought that says that computers in vehicles are shielded, but I take that with a grain of salt, personally. My choice is an early ’80’s model diesel before the advent of electronics, all mechanical fuel system. With a spare starter, solenoid, and alternator stored in a protected enclosure, you should be able to get it going after a few hours work.

      Reply to this comment
  17. CapitalistPig January 16, 22:41

    My man camp house I bought has a metal roof,walls and a metal frame and studs with the interior being a plywood floor and sheet rock walls. I’ve tried to pick up my Wi-Fi outside and its not possible. Could I be protected from EMP?

    Reply to this comment
    • Rod January 16, 22:49

      I would say no. I have seen an EMP protected shelter and walls, ceiling, and floor are all conductive. Door is VERY special and built to seal when closed. Other openings in the building as well are closed with finger stock grounding. When you are thinking of EMP think of an extremely close and powerful microwave dish pointed directly at you with many, many watts of power. You can see that it would punch right through any unsealed gaps in metal and would go through glass and wood as well. Sealing a building for EMP is a study in engineering, both mechanical and electrical.

      Reply to this comment
  18. vocalpatriot January 24, 16:24

    Lots of incorrect and plain dumb information in this article. I don’t recall news of any airplanes falling from the sky when hit with lightning or C.M.E.s .The skin effect, which is the principle of how a Faraday cage works, does protect the electronics on planes and in cars to some degree, you will find that cars are better protection than most believe. it isn’t an all or none situation…further..just buy spare modules in case the ones in your car DO fail, maybe the radio, too. The rest of the car will likely not be affected..but, cheap insurance. HOWEVER, because of the windows and doors on these vehicles, anything stored in them won’t be protected enough. Microwaves actually ARE Faraday cages BUT are designed to keep specific frequencies inside and E.M.P.s are broad spectrum bursts with HUGE levels of power. So, a chicken wire Faraday cage will not work. There must be no gaps in the conductive cover. even a small pinhole or slit can allow some damage. This is why a metal trashcan or altered ammo can would be the best bet. Also I’m not buying the tinfoil on the box trick, because the amount of power involved may render it “invisible” to the emp. It could act as a capacitor and simply pass the energy right through. Mass will your friend..thick metal boxes and cans would be your best bet. Insulate the stored items with plastic or cardboard form the inside surfaces of the cage and the further from the side wall the better.
    Good luck danger rangers!

    Reply to this comment
  19. Johnny D February 3, 07:10

    After reading the 15 and the comments… for the most part I think the information is accurate (especially as corrected in the posts). What I was surprised by was the comment indicating Solar Panels would stand a chance against the E1 emissions of an EMP. Fundamentally, solar panels are arrays of semiconductors where the gate lengths are quite small (not as small as communication equipment or computers…but I would think still susceptible without protection. Thoughts?

    Reply to this comment
    • Rod February 3, 17:11

      I have seen this same idea in a number of venues and have my doubts as well for exactly the reasons you stated. I would really like for someone to do some 3rd party testing so we would know for sure. It is possible to do this with EMP generators made specifically for the purpose and used every day testing EMP shielded facilities. Not sure I would trust a manufacturer’s claims without seeing the test methods and data.

      Reply to this comment
      • Johnny D February 23, 04:56

        Hey Rod,
        I haven’t seen any manufacturer spec out a semiconductor for EMP. Keep in mind that the very physical characteristics that define modern semiconductors for fast/low power use (gate-length) is the very characteristic that E1 attacks. Normal zenar diode protection (for anti-static damage) is too slow for an E1. static electricity damage is more E2, or lightning effects (much easier to protect against…oh and the principle reason why planes are fine in a lightning storm). With respect to Faraday Cages… The casual enthusiast really just doesn’t get it. A screen room (a real Faraday cage, spec’ed out and tested for emissions) is a big deal. A metal box (electrically) is not that easy to accomplish to protect against a broad spectrum event. I like the metal trash can, but even with that, seal all metal junctions with aluminum tape and a non-conductor liner on the inside AND a shield bag for your goodies. I am figuring that combo should give the enthusiast about 50dB of protection.For the cost benefit, I have seen nothing that even comes close.

        Reply to this comment
        • Rod February 23, 16:50

          Johnny D. I agree, but have to tell you that the professionally made shielding that I am familiar with is nothing more than a steel box with fingerstock on the doors and the items inside are bonded to this box without any insulating material at all. I have been suggesting to those without a lot of real world EMP experience to use a galvanized trash can, sealed with aluminum tape, stored in the lowest part of the building, such as a basement. Depending on their distance from the detonation (if it an EMP device) that should get them by unless they are right underneath and then most things will be toast anyway, even the professional stuff.

          Reply to this comment
  20. riverrat February 25, 17:18

    Unfortunately the author seems to have inaccurate data For instance, shipping containerss have a wood floor which does not allow for protection. Solar panels have a diode that requires special connections after an EMP. Flashlights using bulbs not LED will work after an EMP. and much more.

    Reply to this comment
  21. riverrat February 25, 17:23

    I forgot about the solar EMP, under the potential of a plasma blast, it would cause more damage than a nuclear blast from an electronics perspetive. Search on the plasma blast crater in northern Africa that many thought was a meteor crater!

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