How to Build a Faraday Cage: Step-by-Step Instructions

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[CityPrepping]

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[jeanlui]

Hi Chris,
I have 40 years of background as a telecommunications technician. I have worked in Faraday cages on several occasions. Those cages were to greatly suppress radio frequencies during tuning and calibrations. Anywhere near an EMP nuke and I doubt they would protect much. However, some principles are applicable to EMP protection. For instance, as build, the grounding cable acts as a near perfect antenna, thus defeating the purpose of the cage. The powerful signal makes into the box quite easily. As mentioned by someone else, welding a lug on the outside would eliminate this issue. However, most information I have read on Faraday cages from engineers do not recommend grounding the cage. You do not want the currents to flow thru the box to the ground, as this high energy current will induce currents inside the metal enclosure, defeating once again the cage. Another point is the choice of a grounding point. If a very powerful EMP hits, telluric (ground) currents are induced, so would work their way into the house thru water pipes and the grounding wire. Incidentally, solar flares do not produce the same type of EMPs as nukes, but rather create a very powerful ground current. So, your equipment could be damaged just by a flare, in peace time! An added point for improvement, the more layers the better. So, if the items going inside the box are small, like a small walky-talky or thumb drive. First wrap them in paper, then aluminum foil, then more paper, one more layer of aluminum foil and a final paper layer. This greatly increase the attenuation of any signal that might get into the box. Some numbers I have seen indicate that each layer could add an attenuation factor of 1, 000. This level of protection is cheaply achieved with paper and aluminum foil. Still, any cage is better than none. One last point, most studies I have read indicate that an EMP nuke would be detonated over the center of the continental US. I you live anywhere near that area, think multiple layers! Cheers.

[nunyabidness]

Keep in mind that doing the grounding wire the way shown can also cause the RF part of an EMP pulse to radiate *into* the box. As you mentioned, grounding isn't strictly necessary. If you're going to ground, though, make sure the ground wire is attached to the *outside* of the box.

[billsedutto]

I’ve seen a number of videos on how to make faraday cages in different size but you are the first to actually ground. Thanks!

[watsonink]

You can also use Conductive tape around the top for a seal, that way you do not have to worry about the rubber seal. I have made a couple of these on ammo cans and trash cans.

[clarkkent]

It’s important to be able to keep what you have in a SHTF situation and day to day actually. Thank you for the detailed instructions. Secure your preps family. Side note. Another good idea that I use is to add a power charging block. Fully charged and if possible a solar rechargeable one. Take care.

[davidjohnson]

Pretty informative a good example of a simple Faraday cage. Few points, 1. if you isolate the items in the box, you don't need to ground it. Also if you drill & tap a lug on the outside you can use it as a grounding point on the outside of the cage. If you want a air-tight sealed box, you can drill and tap a wire inside to the top cover & bottom box to connect the two pieces. Then you can keep the rubber seal in and just use aluminum tape or tin foil to ensure the cover overlaps with the box more for better protection. If your looking for storage... use an old metal office storage cabinet. Similarly, tap a cable to each drawer and provide some overlapping either aluminum tape and tin foil or other means to overlap the gaps of each drawer.

[TacticalPRN]

Super interssting. Didn’t realize you had to pull the rubber seal. I would like to see the radio test with the ammo can before modifying. I’ll have to test this out myself

[TheTdub]

One other thing you might want to consider is putting a multimeter in one of your cages. This may prove handy if there is an EMP or CME and you need to test or check things out in the aftermath.

[thedrummer]

Home Depot sells copper foil tape that conducts on both the copper and the adhesive sides. I use it on all the faraday cages I build. Also, Home Depot sells spray rubber coating in aerosol cans...better than cardboard...you def want that mask on though when you spray it.

[Norwolf]

Great video Kris. I don't remember seeing anyone else ground their cages. I'll keep that in mind for sure. Cheers from Alberta!

[David_Avidmind]

For an EMP etc. Do not ground a Faraday cage, you have actually just connected your box to a long conducter, the ground in your house goes to the neutral bus and then to the grid, the exact opposite of what you need. "For a "six sided shielding box" (faraday cage for equipment not in use).... "you need a very low inductance to ground. This is desirable for HEMP and IEMI. Ground rods have high inductance, and while necessary for lightning, are of limited help against high frequency transient phenomena". `DHS-CISA EMP protection and resilience guide, Version 2.2 – 5 February 2019 unclassified.`  it also refences the various mil-spec standards.

[rquest]

Another way to test the effectiveness of cage is to place a cell phone inside and then call the number, if it rings, it failed. I would want an external mount for grounding. Just to make sure it had a solid contact point. Excellent, informative video.

[michaeltitus]

enjoyed the beat and the low volume it was at. Also enjoyed the instructional vid.!!

[danielledunavant]

I made a faraday box out of a galvanized metal trash can doing much the same as shown in this video. I keep an old cpap machine that works inside as well as a solar generator, radio, flashlight, CO2 detector among a few othetr things. Living in an apartment I don't have any idea how to ground it, however.

[autumnwest]

You knowledge of different subjects is impressive.

[PapaiUrsolino]

Great video! My suggestion is to actually have a small Faraday box with the very minimum necessary for communication (radio as cellphone towers may be dead) after a first EMP/CME. If it's a EMP, chances are that subsequent attacks may follow and if you have only one Faraday box with all your electronics, you may risk to have them fried in a 2nd, 3rd EMP.
Don't carry all your electronic stuff in a single basket.

[Carepedoit]

Enjoying these. I would not have thought to pull out the rubber seal!

[robintaylor]

You can also use a metal trash can for larger items, with metal tape, aluminum foil and cardboard. To test it, put a cell phone in it and then call it. If no ringing it is good.

[samcantu]

My suggestions for a more effective cage that I implement myself.
-Coat the inside with rubber, 2-4 coats of using spray on (other than where metal to metal contact is needed for the lid)
-Fabricate a thin lead insert w/top that will fit inside and apply rubber coat as with can.
-Weld or solder ground connection on outside of can
-Store on a rubber mat