# Faraday Cage Question - EMP



## Sir Publius (Nov 5, 2016)

I posted a thread a few months back regarding the use if popcorn-like tins for use as faraday cages. There seemed to be a consensus that this should work if the seams are properly sealed, especially considering you could put tin inside of tin for extra protection...which is what I'm doing. My question is, I've been trying to find information on whether or not the THICKNESS of a faraday cage makes a difference in its effectiveness, since those tins are so thin, and if so, how much of a difference the thickness makes. I'm a little concerned these tins aren't thick enough....but maybe they are. Maybe I'm thinking about this wrong, and as long as they are 100% enclosed by metal it doesn't really matter...but I don't know. It seems to me it would work, but I was looking for confirmation, and haven't been able to locate any such website....one that references thickness and its import. Anyone know for sure...if the thickness of your cage matters, and if so, how much it matters?


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## MaterielGeneral (Jan 27, 2015)

Here are a few videos from Dr. Arthur Bradley. If I remember right he is a NASA scientist. If your questions are not answered then try going to the about tab, click it then click send message. You never know he might answer you.


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## Sir Publius (Nov 5, 2016)

Great videos MaterialGeneral, thanks. Especially in conjunction with one another, they offer up a pretty good overview of how much protection is offered with faraday cages, and why. I've seen the 3rd video before from another thread, but not sure I saw the other two before you posted them. 

To summarize the videos for anyone interested in how they may pertain to my specific question, I can't say Dr. Bradley directly addressed my question, but more than a few deductions can be made from all three videos. As far as thickness of a faraday cage is concerned, and how it effects protection, I know they are different materials sort of, but a thick galvanized garbage can whose seams were sealed with metal tape offered something like 40 db of protection, whereas those static-free bags, specifically the dri-shield 3400 bags offer something like 50 bd....and of course they are thinner material than the garbage can. Although, it may not be that simple...I don't know exactly what those dri-shield bags are made of...if they are simply tinfoil bags, which if they were, would surely blow a hole in the idea that thicker is better, or if they are made of more specialized material than just a tinfoil material of sort. So in other words, thicker is not necessarily better, but it may depend on the material. In any event, all seams being properly sealed is very important, as observed in all three videos. 

Another observation from those videos, not surprisingly, is that faraday cages INSIDE of faraday cages offered more and more protection. So popcorn tin inside of popcorn tin would in fact double up protection, as he demonstrated that dri-shield bag inside of dri-shield bag offered more and more protection. That was one thing that made sense to me, but was unverified until I watched the 1st and 2nd videos, particularly the 1st video. 

The good doctor also stated that 50 db of protection should be enough protection against pretty much any EMP pulse, and also seemed to insinuate in the 2nd video that this could be accomplished by something as simple as a wood box wrapped in tinfoil. And important to note, though I could be wrong, is I don't recall him even saying it had to be wrapped numerous times, though it was a heavy duty tinfoil. That being the case, it would seem that popcorn tins, if the seams are sealed properly, SHOULD work just fine in fending off enough db's to make it an effective faraday cage, especially if and when one is placed inside of another. 

Great videos all. Thanks for posting them. If I'm wrong on any of that, anyone feel free of course to correct me...I'm sure you all will...lol...but that seemed to be my take from these videos. Thanks!


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## sideKahr (Oct 15, 2014)

@Sir Publius I think you've got it essentially correct, my research agrees with yours. Thickness does not matter because of a phenomenon called "the skin effect"; as long as the metal is continous with no holes you're golden. Taping the seams is important, an untaped seam can act as a slot antenna allowing the radiation through. If you use multiple shields, each must be separated from the other by an insulator. Popcorn tins should work just fine.

Be advised, most EMP attack scenarios use 30-50,000 V/m as a probable maximum field strength at ground level for North American lattitudes; but some work has been done on Super-EMP devices that could be much more efficient at creating gamma radiation. Speculation is that the North Korean "fizzle yield" bomb tests, originally called failures, would actually have made excellent EMP devices. Efficient EMP producing devices don't necessarily have to be large yield weapons. In fact, simple low-yield fission bombs are better at producing EMP than expensive, hard-to-build thermonuclear bombs. If you want to read more on this subject, see my link.

Over protect if possible, it's cheap and can't hurt.

http://www.futurescience.com/emp/super-EMP.html


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## paraquack (Mar 1, 2013)

Thanks for the link sideKahr, I thought I had all of Jerry's articles on EMPs


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## Illini Warrior (Jan 24, 2015)

if the tins worry you - it shouldn't - do a tin within a tin and add some tin foil wrap also (insulating material barriers in between) ... gauge of the metal envelope is no factor in protection - but a complete enclosure is everything - in particular where any seams or overlapping of metal sections .... just one reason I don't care for wrapped boxes ...

if you watch the garbage can lab testing UTubes - note where the prof adds copper tape to the lid mating area and even covers the handle rivets - that loose fit and gap between lid & can body isn't tite enough .... a gap filling using 000Fine steel wool accomplishes the mission also - and is totally re-usable - never forget that both EMPs and solar wave emissions won't be once and done situation - you'll need to use your electronics and re-pack - use and scoot - use and scoot


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## Redneck (Oct 6, 2016)

Illini Warrior said:


> a gap filling using 000Fine steel wool accomplishes the mission also - and is totally re-usable - never forget that both EMPs and solar wave emissions won't be once and done situation - you'll need to use your electronics and re-pack - use and scoot - use and scoot


Here is a pic of me resealing my garbage can, after taking out the solar generator & using it enough where I could recharge. I think this steel wool gasket is more practical than tape.


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