Should You Ground a Faraday Cage?

[@richryan6326]

Finally, a video I can point to when people argue with me about grounding their faraday. Thank you

[@disasterprepper]

Thanks Rich. That was the point of doing it.

[@aCycloneSteve]

@@disasterprepper As I said in a previous post, It would have been nice if you had tested with the door open, Just as a baseline. To show the cage is working.

[@disasterprepper]

@@aCycloneSteve Yep, agreed. I didn't think that was necessary, but you're right. It would have helped people to better understand the protection the cage offered.

[@lylemacdonald6672]

This was informative. Over 40 years ago I spent time conducting experiments where patient EEG recordings were made. We had to put patients inside a large Faraday cage made from fine copper mess to shield electrodes from picking up 60 cycle interference from overhead lights but the lab was being swept by a radar testing facility nearby and that really fried our recordings and so the need for the cage. It is amazing how well they work.

[@KristofferMyhre-v7b]

fried the curcuitboard or the copper mesh?

[@tmt8425]

Thanks for clarifying with testing to give a definitive answer to this debated question. Todd

[@disasterprepper]

You're welcome Todd.

[@disasterprepper]

@@dawid1803 Sure it is. The shielded box provides about 40 dB of shielding with the mesh. Not ideal, but it is used to demonstrate my point about grounding.

[@disasterprepper]

@@dawid1803 A large conductive structure like this would act as a barrier, providing both reflection and absorption losses to RF waves. The closer you were to the back side of the barrier, the lower the fields would be. It's complicated though because the waves can bounce off things and come in from behind as well.

[@jimmieblue6262]

Great video I'm grounding my cage anyway that tiny difference could make the difference between working and not. Who knows what kind of technology they have that we don't know about.

[@nonamenoname9113]

Outstanding explanation and demonstration! Thank you Dr. Bradley!

[@waylonk2453]

I appreciate the clarity of the experiment, I just wish I'd seen this before adding a ground wire!

[@GoshenPrepping]

Hi Dr.Bradley. Dr. Wormsley here from the channel Goshen Prepping. Although clearly, your results show that there is barely a difference in the radio fields entering the cage between grounded and ungrounded. However, isn't the ground in place to counteract the Compton effect? Ionization that could damage the equipment inside?

[@disasterprepper]

The Compton Effect refers to Compton Scattering. This is just the effect that occurs when electrons are produced by gamma rays hitting air molecules. It's why we have such a powerful electromagnetic wave felt at the earth's surface. Grounding a cage won't affect the incident field felt inside the cage in any measurable way.

[@jeansroses7249]

thank you! All the material I had compiled in order to build my faraday cage, which included advice from several different experts, led me to utter confusion, cuz some said you absolutely must ground, and some said you absolutely must not ground. This test helped me see the difference

[@lepidoptera9337]

Most statements by amateurs about physics are complete bullshit. Having said that, they should have taught you in high school what a Faraday cage does and from that it should have been clear that "grounding" won't do a thing.

[@PowderMill]

⚠️. Forgot to add. THANK YOU DR. BRADLEY! You provide so much information and FACTS regarding the EMP/CME mysteries. You are truly doing lifesaving work and making it available to everyone here. Thank you. !

[@auntieauntie5633]

Thank you EMP DOCTOR 👍

[@levistrauss143]

Great info for the average Joe....I love your books...

[@disasterprepper]

Thank you!

[@hughmungus913]

Given the grounding effect is minimal, would it not make sense to ground for an extra layer of protection from lightning strikes, electrical shorts etc?

[@zahney1225]

You explain things so amazingly. Thank you for teaching us all.

[@disasterprepper]

You're most welcome.

[@darylcheshire1618]

In Monash university I watched this guy conduct a test of a ceramic insulator. There was a whining noise and then a big spark arced with a bang about a foot around this ceramic support. This was contained in a shed of corrugated iron and I was told this was to block the EMP from affecting the other electrical devices in the building.

[@prepperchris1]

i love how in 4 min my homework is done normal it take hrs and days thank you sir

[@harveyblack2699]

Great Information! Great Video. Thanks Arthur! I will share this to other channels.

[@Squirrel200]

This old Nerd thanks you great video! Short and to the point. Thanks

[@jmontarsi]

Thank you for clearing up the issue.

[@rpbajb]

Thanks for attempting to clear up a lot of misunderstanding about this subject that I constantly read on the internet. I consider you, along with Dr. Peter Pry, the authorities on this subject.

[@disasterprepper]

Thanks. I've met Dr. Pry, obviously a very knowledgeable and passionate individual.

[@unclearvin3718]

Thank you. Proves my intuition correct.

[@PowderMill]

👍🏻. FINALLY… A real answer to the “grounding question”! Thanks so much Doc! I have tried to test both grounded and ungrounded faraday cage devices and never saw much of a change so thought I was not testing properly. With virtually zero clue what to expect from an EMP/CME, I tried everything from 29Mhz to 5GHz and at ERP of up to 110 Watts. I have a Agilent HSA spectrum analyzer I use for duplexer and cavity tuning and it’s upper range is only 3GHz. Knowing what to expect, I plan on re-doing the experiments using different screening materials. Yup.. just boredom. 🤣 Btw - Whenever I speak with fellow EE’s and Amateur Radio Ops, this is THE question most of us have. AND…It’s funny that most every “prepper” type person generally has a pseudo source of RF energy to represent EMP energy is sitting in their emergency communications bag. A GMRS/FRS transceiver. 462.6000 through 462.7250Mhz on the simplex or repeater output frequencies of the higher power GMRS 50W channels.

[@t1d100]

I am an EE hobbyist, with limited knowledge. My interest is not an EMP event, so much, but protecting an electrical DUT from ambient electrical noise, when the DUT has been removed from its metal case, to enable attaching probes and testing. I will use a simple cookie tin. I will electrically tie the lid to the body, with a flexible wire. For this use, should I tie the tin to Earth Ground? Thank you for your help.

[@pb7133]

Very simple answer. Thanks

[@johnfisher5266]

Thanks for this one and thanks for noting the effect of a lighting pulse. Seeing the experiment is WAAAAY better than some guy talking about it. Cheers, John

[@disasterprepper]

Totally agree!

[@lepidoptera9337]

If that Faraday cage was hit by lightning, it would shrink into a tiny piece of fused metal. It takes some serious conductors to absorb lightning. Lightning rods are typically 0.8-1 inch in diameter.

[@scottpeterson638]

THANK YOU

[@mikenkaried4543]

Rich thank you for much for doing all of this testing! you are exactly what we need in times like this. Fyi, grounding you shield doesnt impact radio fields very much (especially if the cage is actually working to reduce radio, but if you DONT ground the cage you may end up magnifying any Electric fields present. Apparently electrical attenuation is also a potential contributing culprit with Electric Pulse type damage?? especially when there are non insulated older aluminum electric wires present?? I once worked at a healthcare system in the IT department (some 10+ years ago) and we purchased every wireless device that had been invented at that point and brought them into a room with nearly every moveable piece of medical equipment to satisfy some open Air electric field and wave safety standards. We used meters to detect signals like the one you have, some of the devices we tested emitted electric and radio at the same time, especially when pluged into a charging device, others just radio fields (I do remember very well the blackberry of that day (the ones that where very bulky and had a new cell phone module installed, they did not originally have a cell phone inside them) and those devices were very noisy, very bad at both types of fields sending out 4-5 times the amount of microwatts per square meter or meter squared... than any other wireless device, however that goes, and if you had two of the blackberries next to your skin you would end up creating as much as 4 volts of field strength onto your skin, electrostatically raising arm hairs. Other devices magnified any electric fields it received from the older (were newish at the time) 2.4ghz vtec phones. In the testing we documented effects of different spectrums and wave and field blocking and also found aluminum foil to be the most effect across the board and the most economical (we also had static bags that we used to ship hard drive and memory sticks, these were not as effective, im guessing because they had holes in them like your chicken wire, and that stuff was very expensive. One medical device was dramatically effected by most cell phones in general, many of the controls would not respond or would start doing things on their own and double and triple aluminum layers didnt change anything, it still reacted haunted (i think it was russian or something, not german or japanese and certainly not chinese back then), however the problems went away when we connected the aluminum sheets to the ground that was part of the machine. Also I found another youtube video describing this same issue requiring a ground to prevent electric fields and also prevent them from being magnified when using the copper sheets or the conductive EMP wall paint. kzbin.info/www/bejne/fJnHkqqLrdOBp7s

[@lepidoptera9337]

Yes, that was a lot of bullshit. ;-)

[@smcary]

Doc, the ferrites and surge suppressors that you sell and advocate for...what class of a CME flare would they protect against? C, M, X?

[@disasterprepper]

Ferrites help to suppress current transients on power wires. It's not really possible to say one type or another would protect from different categories of CMEs. Rather, they offer protection against any transient surge, whether or not it would be enough for your equipment to survive would depend on the surge level, timing characteristics, and equipment sensitivities.

[@TheHillsHaveFPV]

the EMP will generate a magnetic field in the metal can. When you ground it, it allows that field to collapse and dissipate to ground, doesn't it? A stronger signal would induce a stronger magnetic field that might saturate that metal. Would grounding it help dissipate the energy during a higher energy burst?

[@jimjohandes]

Excellent!! Very helpful!!

[@brucewayne-cave]

Great demo Doc ! In your book, I believe you mentioned that a 'ground' wire would be bad in a CME event. That grid tied wires, would act as an antenna; so an ungrounded cage would be better? Is my recollection accurate of your thoughts on CME grounding? Love your work.

[@disasterprepper]

That's still my thought, although I'd like to do some testing to see what negative effects would actually be experienced from a short ground wires would introduce. Personally, I see no reason to ground a Faraday cage if trying to protect from an EMP.

[@johnbarber6620]

Dr Bradley: Does the wall thickness of a Faraday cage matter? For instance would a galvanized steel enclosure have better shielding effectiveness than the same enclosure made of thin aluminum foil? Does thicker material buy you some additional dB of shielding effectiveness?

[@disasterprepper]

I answered this earlier, but I don't see my reply. The answer is if you have about 40 microns of metal thickness, additional thickness has a diminished effect. It has to do with the skin depth of the material. BTW, 40 microns is about two layers of heavy-duty aluminum foil.

[@FancyNoises]

@@disasterprepper have you tested the effectiveness of aluminum window mesh for this? It's thicker than foil, but has small holes- but do they not matter except at extremely high frequencies?

[@disasterprepper]

@@FancyNoises I've worked with screen before and it does pretty well. The difficulty is getting it to lie flat and not create any gaps or unwanted seams. The small holes don't compromise the shielding much, but I found it hard to work with.

[@VincentSmith1776]

@@disasterprepper would the material itself have an effect on the needed thickness - i.e. copper foil tape is typically 36 microns thick but would be great to line a pelican-style case with to add faraday protection? Could you test both a single layer and two layers of copper foil tape for their effectiveness? Or have you already?

[@angelborini4882]

Hello there! I currently have a question. In electric guitars, I've seen that they connect the Faraday cage to ground (GND). According to what was explained in the video, what would be the reason for this? Thank you in advance for the experiment, and best regards.

[@TheFossilChannel]

one important thing is to match the antenna polarization with the spectrum analyzers antenna. i noticed your radio was vertical and the analyzer was horizontal. maybe at the distance it might not mean much but if its further away it will.

[@disasterprepper]

Yes, absolutely true. We're always careful to test both in vertical and horizontal antenna orientations when conducting actual shielding measurements.

[@johnbarber6620]

Dr Bradley: When building a Faraday cage using a painted ammo box, etc., must you remove the paint before installing the conductive gasket material? What do your tests show? Does the micrometer thickness of the paint still allow RF from an EMP to enter the Faraday cage enclosure if you don't remove the paint?

[@disasterprepper]

I answered this earlier, but I don't see my reply. I've tried ammo cans with and without the paint removed and didn't see much difference in terms of shielding. I used to always use a Dremel tool to take off the paint, but I think it's probably unnecessary, and can cause rust issues with the metal.

[@MichaelLenz1]

Hello! I’m interested in calculation methods of faraday cage. I know that high frequency emi is not blocked by foil, but it flows on it’s surface, so having multiple layer of high frequency electromagnetic conductor (like mu metal, copper) foil or sheets will increase the shielding performance. But emp has wide spectrum from >0Hz to around hubdreds of Mhz, but the power of powerfull EMP and methods to calculate the amount of layers quite bit tricky to evaluate. Could you please suggest how to calculate or find more information about this? Thanks!

[@TheHappyGardener]

What about something like the "emp shield" device Would it help that or would it not make any difference at all ..and how credible is that product for cars and home ?

[@maximusmeridius6610]

So I could build a wood structure, cover it with aluminum screening and put it over my generator in the garage and I'd be ok? Should the generator be off the concrete, maybe on plywood?

[@RubyS.1]

Love KZbin perfect answers my question

[@FLTWx]

If my home has a metal roof, does that give me some EMP protection for devices in my home not connected to the power grid?

[@DaveC-sx3gl]

Thank you for making this video. So many opinions out there. I recently purchased a solar generator and was wondering how to protect it from an emp. I've noticed some people build a cage (wood crate covered with fine aluminum screen/mesh) and others completely enclose it in metal. Aluminum foil rips too easily so I'm not sure if that's really the way to go.

[@turtle.trek.2023]

I HAVE AN IMPORTANT QUESTION ( THAT IS CRITICAL ) I am building a bicycle. What part of the solar electrical system . ( Should be shielded to protect the electrical system from an EMP ) Like the solar charge controller . THE BIG PROBLEM WITH THIS. The unit do build up some heat. Has to be vented . So it doesn't overheat. So how do I protect something like this . Effectively from an EMP.

[@ngkahhoe9769]

Hi Dr, Not sure the the hole aperture is small enough to block the EM wave? if it is larger than wavelength, the experiment might not be valid.

[@zeddicuszul4046]

Great vid. Question about what would be needed to make an effective faraday cage room if I’m building an ICF ( concrete form ) home? Does rebar act well enough and at what regular interval distance. If not It is there an easy solution like an emp blanket fabric that you would insert prior to pouring? Thank you for your expertise and willingness to share your knowledge.

[@disasterprepper]

I've consulted for folks who wanted a Faraday cage room in an ICF home, and it came down to three options: conductive paint, conductive barriers applied to the walls (copper foil), or an internal Faraday cage room. They are listed in order from least effective and cheapest to most effective and expensive. You'd want to hire a good consultant to help you do it right.

[@chhopraki]

I just learned something yesterday about faraday cage and faradaic protectionware like silver coated shirts body protection. Unless you are completely encased inside a clothing you wear, not grounding the that conductive metallic shirt is that it becomes a receiver of charge and all other parts of the body that is not protected would actually end up receiving more radiation around where the shirt is being worn, for example your head. In that case grounding would have helped

[@ChristineTence]

Hi, I’m not sure how to message you or ask you other than here in the comments. Im confused because ppl have told me I need to bury my farrady cage underground in order to maximize its effects, but they said the purpose of that was to ground it… so would this mean I do not need to bury a farrady cage? How effective would it be to layer the inside of a 40ft shipping container with copper foil & solder the foil shut? Would that be enough to protect needed equipment in an hemp? I am also planning on keeping a backup used off grid solar system for a house there - what parts of the electrical for my home would I need to store & replace in the case of an hemp? Do I need to store extra wires? Also, are backup wires that are still on a reel & unused - would they be fried in an emp or can they be stored outside if a farrady cafe? Lastly, I have an unused car I was thinking about dissembling the necessary parts that might be affected in that sort of emergency… which parts should I store & which parts would be fine? And if I get a electric car conversion kit or a biodiesel conversion kit, which car parts would I still need to store that are reliant on electronics that are not related to electrical or biodiesel conversion? Thx so much!!!

[@scotthorton7786]

What is your opinion on old vehicles with electrical components consisting only of a battery, alternator, distributor coil points and condenser, as far as their resistance to emp or solar flare?.

[@disasterprepper]

First the good news. Cars aren't affected by solar events (flares, CMEs, etc.). Now the bad news. Cars can definitely be affected by an EMP. Older cars are believed to be less susceptible (makes sense since their electronics are larger in scale), but there's no guarantee that they would survive. If you're worried about it, you might check out our T.R.A.P. products. They're reasonably priced and offer distributed transient protection.

[@ronalddaub7965]

Even a 12 volt coil is sensitive to EMP that's why the military used to have braided spark plug wires and shielded magnetos and or distributors we called it termination as a lineman termination ,(is just grounding The shield of the primary voltage in a high voltage wire) the shielding around the wire that is non-current carrying for safety purposes..()( with tons of insulation for the application.... In other words it's more than 600 volt rated wire when we used to run 4160 we used a high voltage cable for 4160 the higher the voltage the more insulation you need and in line work, but my point is everywhere high voltage goes into a conduit or underground it has to have grounding shielding wire around it and that's what we terminate.. or ground that's why the wire is so expensive and why most electric wires are on top of insulators in the air as well as for cooling

[@308Sharpie]

Is there the possibility of a cage storing a charge and shocking you if its not bonded to ground? Or is that what you were talking about with a lightning strike?

[@chuckmatson7255]

is there something special about galvanized steel, or can i use a steel 55 gallon coated drum?

[@scarygary3569]

Would u protect wires that come off of a grounding rod leading into house or to solar panels,or say the ground wire that grounds a generator motor to frame, say with ferrite?

[@professorg8383]

I get what you are saying, but it seems to me that during a big EMP or CME, power line will likely experience a very high surge, similar in energy to a direct lightning strike. That surge is going to hit all connected wiring. Seems to me that any nearby wiring under this surge, will induce a charge in the Faraday cage. Seems to makes sense then, to ground the cage to dissipate that spike of EMF electrical current. Our power distribution systems rely on grounding to take them down to minimal levels. A lot of factors would go into it, but I can see a a large isolated Faraday cage becoming charged like a capacitor. If whatever you have protected is isolated from the cage itself you will probably be OK, but I still believe that grounding the cage is better than not grounding it and potentially provides some additional protection. For a nuclear based EMP weapon, the grounding is probably not going to be needed. But I believe that depending on other surrounding factors like building wiring a very high energy EMP from a CME, could be at far higher energy levels. I'll ground my cage, cage, thank you. particularly if it is sizeable. Just my opinion, but I belief a CME or very large solar flare based EMP, is probably more likely than a weaponized deliberate one. However, after the fact of a very big CME, there may well be some new incentives to use weaponized EMPs to create a big advantage. I wouldn't worry about a small box type Faraday cage being grounded. I tend to favor a larger scale approach of a garage sized Faraday cage and using small cages in the bigger cage for sensitive electronics. It's tough to make a large Faraday cage that is perfect. It's liable to have some "leaks" that allow certain frequencies in. I figure there are primarily three things you want to protect. Communication methods, like HAM radios and maybe a few walkie talkies. Transportation. which cold be a variety of possibilities. Basic, non electronic dirt bikes would be better than nothing. An old car or pickup pre electronic controls, Maybe keep a spare ECU in one of the small cages, for your daily driver vehicle that you won't shield. And third, electrical generating capabilities, like a mid sized gas/diesel generator, some solar panels and small inverters. The odds of everything getting fried are slim and some stuff is probably going to be worthless like your fancy smart phone. Have a good master plan and you can always use some steel garbage cans with tight fitting lids for misc stuff it might be nice to have, but not critical. Depending on energy levels involved, the simple steel trash can might be enough protection for some stuff. Just make sure whatever you store in it, isn't touching the steel walls of the can. Figure that what you are doing may not be government grade perfect, but just improving your odds through hardening. A few other things you will want, but the EMP won't effect them. Long storage food, medical supplies Some fuel and security protection. Ideally we won't need this stuff, but most of the time you don't need a seatbelt, airbags or fire extinguishers, but they are good common sense precautions,

[@michaell1665]

I just found your very informative channel and subscribed. One question: If one was constructing a garage-sized or shed-sized EMP room to protect larger equipment (i.e., vehicles, etc.), could one make the case that running a sizeable grounded grid with larger conductors might have the advantage of diverting lightning strokes to ground and maybe protecting the foil envelope of the Faraday Cage for its true purpose later? I am no EMP expert here by far, however, I wonder also if the quickly ramping and high frequency / short duration of a true EMP or solar CME might result in a benefit from including an earth ground to drain at least some static charge. Thanks for your work!

[@disasterprepper]

Hi Michael, yes, large conductive structures like the ones you mentioned should always be earth grounded.

[@jameskrivitsky9715]

Thanks Dr. B for showing a basic test result. Also a good point you make that an EMP pulse and electro-static discharge ( like lightning ) are different and that grounding is essential during a lightning storm. So far my Siemens whole house protector unit has been working during the Houston area thunderstorms. JwgK

[@j.d.preppingerie6522]

Thank you

[@jwgbmp40]

so is it the idea that inside a metal container the items will be protected by the metal container "reflecting" the pulse back outward? must the walls of the metal container be lined to insulate the items from the metal container? if so, with what? also, it seems grounding the container would be beneficial, look at lightening strikes?? not sure I understand the "insignifcance" of grounding??

[@mannyfragoza9652]

according to someone who was in the military and a prepper on youtube said a Microwave is a good Faraday cage but only if its grounded. Do you have any experiments using a Microwave oven? or do you agree with this?

[@amdenis]

Does the type or grade of steel matter, such as galvanized, 704, etc?

[@johnbarber6620]

Dr Bradley: Can you leave the TRAP plug in one of the generator output sockets while the generator is running, or must it be removed?

[@disasterprepper]

Yes, the TRAP plugs can be left in when the generator is running.

[@GoingGoneGalt]

So, just like lightning does not follow the same rules as "low" voltage electrical potential, why would we confidently conclude that the kind of momentary rf energy we are talking about would behave the same as a little two watt transmitter? It seems to me it would be a different ballgame.

[@spaceywilliams8637]

So would grounding it make it not work as effectively or is it one of those dont really need it but might be better safe then sorry deals

[@OldPopPop2u]

What about putting a capacitor in the circuit before grounding it?

[@tartie-2-shoesstockwell119]

i always hear that you could be shocked by your faraday cage if it wasn't grounded, is it true that it could have a charge to it that could shock or electrocute me in an emergency situation if i dont ground it beforehand?

[@AnotherMe890]

It would have been interesting if you had opened the cage up afterwards and did it one more time to show full signal strength and as a result how many dB the cage was blocking. Thank you for the video!

[@disasterprepper]

I answered this earlier, but I don't see my reply. Yes, I probably should have done this. The signal level would have jumped up to around -30 dBm. I always get nervous driving the spectrum analyzer with such large signals.

[@AnotherMe890]

@@disasterprepper very true, it could over range it, but I would suspect that the spectrum analyze would have protection diodes in it to prevent damage from an overly strong signal coming in the antenna.

[@markchase5323]

@@AnotherMe890 Actually they don't but usually have a label or a manual statement as to the maximum input allowable. Most of the HP stuff had +30dBm as the max. That's one watt at the characteristic impedance selected.

[@quiettime6871]

Does a shiny surface help reflect the EMP energy?

[@WilliamRedfield1528]

Interesting Video and comments. My only concern with grounding important electronics with a farady cage has do to with how strong the dbm signal would be during a carrington level solar event.

[@disasterprepper]

Solar events won't couple into free-standing electronics. Rather, they couple in mile-long conductors, which then feed into electronics. If something is unplugged, it won't be harmed by a solar event.

[@davemeeks8109]

Does this apply to CMEs as well? Would the Carrington event be the same if telegraph lines were grounded.

[@disasterprepper]

CMEs cause very powerful transients on long conductors, so it's not really a matter of shielding small free-standing devices. Properly grounding those systems attached to the long conductors would be important.

[@andrenovelliromansl]

Hello! How was the measured dbm with the analyzer outside The cage?

[@xpto3698]

Nice experiment! The reduction efect is equal inside all the cage? Should it be stronger in the center if the cage was bigger?

[@charlieklinkert7607]

Dr. Bradley, wouldn't a ground act as an antenna picking up energy from an EMP and redirecting it towards the Faraday cage?

[@disasterprepper]

I've heard this said, and perhaps even said so myself, but I don't really know that it's true. For most household grounding setups, I think attaching a ground wire would be a net zero effect.

[@charlieklinkert7607]

@@disasterprepper Thanks for your reply.

[@spaceywilliams8637]

Another question is it possible to protect your electronics from an emp by burying them

[@terryglendening7166]

If I make a faraday cage out of an ammo box and store it under my deck touching the ground, is it grounded?

[@johnbarber6620]

What happens to items internal to a Faraday cage that are in contact with the interior wall? Is the shielding effectiveness lost or attenuated? People have said to line the cage with cardboard, etc., but no one I've watched has said what happens if you don't line the cage with an insulator or if the insulator falls aside and lets a device you want to protect touch the inner surface.

[@disasterprepper]

If a metal item inside the cage came into contact with the interior wall, it could experience some unwanted energy. It would also act to bring the energy into the cage and act as an antenna, re-radiating it throughout. Better to keep anything metal from touching the interior metal walls using a cardboard or other insulative liner.

[@5jjt]

I'm brand new to the EMP discussion, and one thing I don't understand is how an electromagnetic pulse damage simple infrastructure like powerstations, poles, lines, etc. Where's the sensitivity in the system that is so vulnerable?

[@Dreadlockyx]

Might be a stupid question but should equipment inside a Faraday cage be protected from the exterior conductive material (i.e. not touch it) ? Say a radio has a metallic body, should I prevent it from touching the housing of the cage by using, say, a towel ? Thanks

[@disasterprepper]

Items with exposed metal should be insulated from the interior of the cage. Most people just line the cages with cardboard, but a towel would work fine too.

[@Dreadlockyx]

@@disasterprepper Got it, thanks a bunch and have a nice day !

[@stuartgray5877]

The answer is YES. Either THAT OR the multiple Military specifications that I have been building EMI/EMC/Tempest facilities to, are all wrong. I suspect that IF you used much higher power test transmitters you would see a falloff in the performance of the Faraday cage if it was not grounded. I built a facility at Ft. Huachuca for testing Abrams Main Battle tanks. The field strength we hit those tanks with was so high that the tank was Physically HOT after the test. The antenna test ranges I have been on could ignite steel wool in your pocket if you walked in front of an antenna when it was radiating. The techs that worked on that range carried the steel wool intentionally so they would know immediately if they walked into an active beam. I believe the question comes down to: If the power of the EMI that the cage is absorbing is TOO high, what happens when you use up all of the charge carriers in the metal? We know that once the metal's charge carriers are "used up" in reacting to the incident radiation, the cage will then begin to allow other frequencies through. So, does grounding the cage allow more charge carriers into the shield to fight the incident radiation?

[@CurryFeatures]

So if an EMP happened and the faraday cage isn't grounded, would it be safe to touch? Or would the cage have absorbed electricity making it dangerous to touch? I ask because most people ground their cages saying that you need to redirect the energy out of the cage to make it safe to touch.

[@ravon1982]

Make sense

[@sembutininverse]

thank you sir 🙏🏻

[@jayl6019]

Does the use of aluminum and copper invoke a bi-metallic problem into the Faraday cage?

[@disasterprepper]

I answered this earlier, but I don't see my reply. The short answer is that no, I've never seen a shielding issue result from using two metals in contact with one another.

[@jayl6019]

Thanks!

[@anzaal]

I certainly would not do comparison test a Faraday cage with one complete side removed ! How about testing any effectiveness of grounding with the Faraday cage completely closed ? Would the adhesive on the conductive gasket cause any resistance ? Being a Ham and frugal (now I've repeated myself), I would wrap the existing gasket in brass window screen and glue back with Barge's cement (since I have that available). Enjoy you videos, thank you.

[@disasterprepper]

The side is not removed. There's a fine conductive mesh in place of a solid barrier. Many Faraday cages are made of fine mesh. I used it so that people can see the results don't change, and I don't have to disturb the setup to open it each time to read the value.

[@disasterprepper]

The thin adhesive on the back of gaskets make no measurable difference. Same goes for the adhesive on conductive tape. I've measured with very expensive adhesive-backed tape and cheap aluminum duct tape, and both did equally well. As for Barge's cement, that would probably go on too thick, and might well cause issues with conductivity.

[@anzaal]

@@disasterprepper ...............Thanks for the clarification.

[@anzaal]

@@disasterprepper .........Regarding contact cement, not having tested, just speculation.

[@dtv5362]

Could an EPM damage pacemakers or defoliators for people with heart conditions, nuclear EMP or a close lightning strike?

[@richardhart7652]

Will a Faraday cage kill the signal given off by a smart meter G4 or whatever it is

[@markchase5323]

My issue with "grounding" or as the Brits call it more accurately, earthing a Faraday cage is the inductance in the ground wire. at 460 MHz, this yields an inductive reactance of approximately 43.7 or 44 ohms XL per inch or about 425ish ohms of inductive reactance per foot. It looks like 2 feet of ground wire or 850 ohm Xl. But wait there's more. All the feet of wire to the ground wire have additional inductive reactance. This is why the grounding of a shield room is located at the shield room and may be connected by braid. Further. all that wire from the Faraday cage to the ground rod acts like an antenna. That is why you may see videos of people attaching a ground wire and the field reading actually goes up.

[@disasterprepper]

Thank you Mark, very well said.

[@mrjon75]

In the USA, we speak of grounding, and sometimes, "Earth ground," or cabinet ground, but we rarely seek advice of the British, as they can't even speak English very well.

[@johningle1959]

@@mrjon75 Good one.

[@drlynch]

Thanks for doing this video. I was going to ground my cages but now I will not.....

[@johningle1959]

Note that if you want to protect against perils BESIDES EMP, then grounding the enclosure is the best method.

[@dp3797]

Do solar panels need to be protected with a faraday cage?

[@LeSandWhich]

can someone explain to me how the faraday cage block out signal ? I thought how it works is the faraday cage conduct the "electro field" of the signal to ground, preventing it from reach anything inside the cage. But then how does it work when it's not grounded ?

[@hummingwind8869]

Dr. Bradley, thank you yet again for another great video. I have a question, I am finding conflicting information regarding aluminum vs steel trash cans used as Faraday cages. I currently have a steel trash can that is lined with cardboard, seams sealed with aluminum tape and am getting your EMP gasket for use around the inner lid. My question is should I be using an aluminum trash can instead of steel? Does aluminum afford better protection? Thank you for time.

[@Glocktard]

Good question.

[@disasterprepper]

Aluminum or steel will work equally well. Both are excellent conductors, and the type of metal used doesn't really affect the results when it comes to shielding.

[@hummingwind8869]

@@disasterprepper Thank you Dr. Bradley I appreciate your answer. Good to know it should be okay.

[@brandagandafilms9698]

So you're saying that grounding is always a good idea/practice.

[@EricJohnson-bk1fx]

would a 20 foot connex work as a faraday cage?

[@hageir]

2 dB is still 2 dB in audio :) Thanks, good to know 🙂

[@ohyeahthatsright3155]

How many DB without the cage?

[@davidgray4894]

Do you have an email address I could send a couple of questions to???? I would greatly appreciate it!!!!

[@disasterprepper]

Easiest way is to go to disasterpreparer.com and click the Contact button at the top of the page.

[@logangraham2956]

the strength doesn't really matter , its the wave length compared to the hole size that matters. take a microwave for example. that screen door only works because the microwaves are larger then the hole diameter of the screen. i'm not convinced you took the wave length the radio produces into account when picking this screen.

[@3nertia]

Even if it's hundreds of miles away, a nuclear EMP would be *a lot* more power than a handheld radio, no? Would that power be enough to make a difference in attenuation or no?

[@ChatGPT1111]

Attenuation is relative to whatever source you have. While it may or may not be a more powerful source, a minus 60dB attenuation enclosure would always provide 60 dB down from the signal or EMP strength. So much better than leaving it out in the open regardless of what creates the EMP.

[@Andrewbreeze316]

Science!

[@kiloohm]

what about capacitance build up within the cage?

[@lepidoptera9337]

I don't even know what that is supposed to mean. Neither do you. ;-)

[@aCycloneSteve]

It would have been nice if you had tested with the door open, Just as a baseline.

[@disasterprepper]

Yes, I could have done that, but I was a little worried about the signal level overdriving the spectrum analyzer. The front end circuitry is rather sensitive to very large signals.

[@aCycloneSteve]

@@disasterprepper I guess I should read your replies before I comment on someone else's post! >:-)

[@disasterprepper]

@@aCycloneSteve No worries, it was a fair point. :)

[@ATLTraveler]

Yes, isnt that the point? Oh your only talking about a em pulse not static electricity.

[@johnbarber6620]

Dr Bradley: Looks to me like the impedance of the ground you used in the video would be pretty high at 460 MHz because the ground lead was seriously bent/curved and possibly even be close to series resonant at 460 MHz. It would be interesting to know if the numbers change with a straight run from the cage to ground.

[@disasterprepper]

I answered this earlier, but I don't see my reply. The short answer is that yes there grounding connection certainly has measurable impedance at 460 MHz. My test was done in what I thought would be a typical setup. To eliminate the effects of impedance on the ground connection would require very short, low inductance ground straps tied immediately to a ground rod. I don't think most people would know how to do this properly, or want to go to the expense to do it, especially when the benefit is so minimal. Good question though.

[@berad3574]

I would’ve loved to see the level when it’s not in the cage too!

[@disasterprepper]

Yes, I should have included that in the video. Sorry, next time. As you'd expect there is some shielding provided by the cage, even with a mesh front.

[@Kane-ib5sn]

he messed up the experiment: he failed to show the Faraday cage has any discernible effect on the radio signal. if the mesh wire has no effect, the grounding will not register as any different.

[@disasterprepper]

I answered this earlier, but I don't see my reply. It wasn't really a mistake, but your point is fair. I didn't show the effectiveness of the Faraday cage because I've talked about that in a number of other videos. I was just focusing on the ground connection effects.

[@Thumpertom]

I sent u an email asking u to contact me about what exactly I need or should buy for the stuff I need to protect.. such as a solar system..

[@disasterprepper]

I replied to several emails recently asking this question, but I'm not sure if I received yours. Can you please send me another email today to [e-mail]? I never ignore emails, so if you don't receive a reply, it means I either didn't receive your email or my emails are getting returned to me as undeliverable (happens sometimes to .net addresses).