# Faraday cage...would a...



## TheLazyL (Jun 5, 2012)

Would a 20' x 30' pole building sided and roofed with steel act as a Faraday cage?

Would a steel gun safe also act as a Faraday cage?


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## Onebigelf (Sep 17, 2011)

Properly grounded, yes, to some extent. The safe more than the building which has a lot of surface area (that much wave propagation front is not your friend if the pulse is large enough). You can cross the line between Faraday Cage and Antenna with enough umph...

John


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## rickfireftr (Feb 21, 2012)

Take your cell phone with you. If the signal can get thru so could the pulse of an event. It is an easy test and not really actuate. But since no electronic (modern) equipment has had to sustain an actual massive emp from sun or nuke it is a crap shoot. Tin foil seems to work really well around equipment you need to protect.


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## CulexPipiens (Nov 17, 2010)

In theory the safe should, although you need to make sure whatever is on the inside is insulated from the metal of the safe.


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## weedygarden (Apr 27, 2011)

*Good question!*

I am glad that this question was asked. I have wondered if there was some way to make a building into a faraday cage, such as a shed or garage.


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## NaeKid (Oct 17, 2008)

weedygarden said:


> I am glad that this question was asked. I have wondered if there was some way to make a building into a faraday cage, such as a shed or garage.


The number one thing that has been mentioned about a faraday cage is that there cannot be any form of electrical-input to the building. The power-wires will act like an antenna and allow the EMP inside.

The best "building" that I have heard of that will do well as a faraday cage is your basic 5-sided tin-shed that is properly grounded (sitting on the ground works just fine) and that has no power wires running into the shed (for lights, etc). To add another layer of protection, using sealed metal containers inside the shed can keep very sensitive electronics safe, as long as the electronics are shielded (insulated) from the outside of the metal containers.

The metal containers could be as simple as a 4-drawer filing cabinet and the insulation could be as simple as a computer anti-static-bag. Anti-static foam envelopes also work wonders.

A faraday cage is a very simple unit, but, it needs to be always in use - anything outside the cage could be damaged by EMP and you will have zero warning that an EMP-burst is on its way just as you would have zero warning about the first lightning-strike in a thunderstorm.


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## chris88idaho (Apr 30, 2012)

The thing is, you can never test for emp so you'll never really know if you are safe. Best suggestion I have is you can never over prep for this type of event. Redundant counter measures in different forms would seem to be best. No grounding could be to excessive. Remember to keep electronics insulated from the shield.

I have heard a simple garbage can can work with a piece of foam in it. The theory is sound, but you'll never know unless it happens


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## weedygarden (Apr 27, 2011)

If we have an EMP, I know most motors and engines won't work. And maybe you don't want to be the only one with a running anything.

I was wondering about having something large enough for a motorcycle, garden tractor or tiller, a solar panel and necessary accessories, so that after the fact, these would be able to be taken out and useable.


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## bahramthered (Mar 10, 2012)

Before you go insane prepping for an EMP you really have to ask what are your odds of being hit by it? Like most things EMP is diminished the further it gets for it's source. 

Are you near a first strike target? If your not, then you might consider skipping these prep. If it happens your exposure to a far away EMP or solar flare might be a bit of static.


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## LincTex (Apr 1, 2011)

weedygarden said:


> I was wondering about having something large enough for a motorcycle, garden tractor or tiller, a solar panel and necessary accessories, so that after the fact, these would be able to be taken out and useable.


Just buy the spare parts. A set of points, condenser and ignition coil take up a whole lot less space than an entire engine, let alone an entire tool (rototiller, etc.).

Same with other things - spare rectifier and voltage regulator for the alternator in the truck (or just an entire spare alternator, they are small) and also a spare electronic ignition module, pick-up, and ignition coil for your older 70's era vehicles. You can buy an older motorcycle, drain the carb and gas tank, then remove all electronic parts and store them in the Faraday cage.

Also, be on the lookout for older military equipment powered by Wisconsin or Onan engines with shielded ignition systems - you can tell because you have to use tools to take a large and heavy spark plug wire off, not the kind you just pull off.









You can also add shielding to existing ignition systems with some thought put into it.

I put a cell phone in an old (unplugged) microwave, and the signal strength goes away 100% (and it will not ring) so that is a possibility.


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## NaeKid (Oct 17, 2008)

weedygarden said:


> If we have an EMP, I know most motors and engines won't work. And maybe you don't want to be the only one with a running anything.
> 
> I was wondering about having something large enough for a motorcycle, garden tractor or tiller, a solar panel and necessary accessories, so that after the fact, these would be able to be taken out and useable.


If an EMP-event happens over Hawaii, those on the main-land of the USA probably wouldn't even know it happened. If it happens on the west-coast (say over San Fransisco), those on the east coast probably wouldn't know that it happened. I expect that if it was an attack, there would probably be a dozen (or so) EMP-bursts that happen simultaneously in order to have the best affect.

My tin-shed in my backyard holds my KLR motorcycle just fine on one side, gardening-supplies and other similar goodies on the other side. The problem is that it isn't easy to get the motorbike out quickly, so, I have to plan for it. Most of the time I am lazy and leave all of my motorbikes in my attached garage where I can just hit a button and raise my garage-door.


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## Ration-AL (Apr 18, 2012)

comes with electrical discharge grounding strap, my thinking is if it must be sealed to keep dangerous fumes inside then it will keep an emp out, plus if it's built to shed static electricity to prevent explosions it must also shed the current from an emp, and besides i got as a left over from work and is the proper way to store flammable materials , i keep all of my fuels in there along with a spare ignition system for my old aircooled van.


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## CulexPipiens (Nov 17, 2010)

chris88idaho said:


> ...I have heard a simple garbage can can work with a piece of foam in it. The theory is sound, but you'll never know unless it happens


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## TheLazyL (Jun 5, 2012)

CulexPipiens said:


>


FM radio reception...that answers my question! Thank you for posting the youtube link.

In my 20' x 30' steel covered pole building I do have a FM radio that works only by the overhead door and only pickups strong local channels. So I'd guess I have leakage around the overhead.

I have to find someone that owns a gun safe and see if a FM radio receives when the door is closed.


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## LincTex (Apr 1, 2011)

TheLazyL said:


> FM radio reception...that answers my question!


Maybe... Maybe not.

The EM in a FM radio signal is pretty dang weak.... 
an EMP pulse is something like several KV/per sqM....

That is WAAAAY stronger than an FM signal.


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## CulexPipiens (Nov 17, 2010)

TheLazyL said:


> FM radio reception...that answers my question! Thank you for posting the youtube link.
> ....


I wouldn't take the video as accurate reliable info, but rather a demonstration of how a faraday cage works and a simplistic way to test something... but short of hitting your "cage" with a full EMP we don't really know until (if/when) it happens, if your cage really will protect your equipment.


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## TheLazyL (Jun 5, 2012)

LincTex said:


> Maybe... Maybe not.
> 
> The EM in a FM radio signal is pretty dang weak....
> an EMP pulse is something like several KV/per sqM....
> ...


I'm thinking about the garbage can Faraday cage inside of my steel sided/roofed pole building. Almost a Faraday within a Faraday me thinks.


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## Beaniemaster2 (May 22, 2012)

http://mastersconnection2020.com/in...g-your-electrical-equipment-from-solar-flares

If you haven't seen it, National Geographic had an excellent documentary on this... Electronic Armageddon Best 45 min you could spend...

http://video.nationalgeographic.com...pisodes/explorer/ngc-electronic-armageddon-1/


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## BillM (Dec 29, 2010)

*Do Not*



TheLazyL said:


> FM radio reception...that answers my question! Thank you for posting the youtube link.
> 
> In my 20' x 30' steel covered pole building I do have a FM radio that works only by the overhead door and only pickups strong local channels. So I'd guess I have leakage around the overhead.
> 
> I have to find someone that owns a gun safe and see if a FM radio receives when the door is closed.


DO NOT, get into the gunsafe with the FM radio and shut the door just to see if the radio still works! !

:2thumb:


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## Daphnetree (Jun 20, 2011)

I have heard a metal garbage can works, so I have my radios all in a metal file cabienet. Does anyone know a reason why that would not work.


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## CulexPipiens (Nov 17, 2010)

Daphnetree said:


> I have heard a metal garbage can works, so I have my radios all in a metal file cabienet. Does anyone know a reason why that would not work.


Scroll back to message #13 for a video on this.

As to why it would not work? Because short of actually triggering an EMP to test it, you can't be certain. Anything we do is a best effort and hope it's enough if it's ever needed.


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## casey97 (Jun 23, 2012)

Everyone has a small Faraday Cage in their home already. If given a little warning place small electronics in an unplugged microwave oven. It keeps the radiation in for cooking, it will keep radiation out as well.


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## LincTex (Apr 1, 2011)

casey97 said:


> Everyone has a small Faraday Cage in their home already. If given a little warning place small electronics in an unplugged microwave oven. It keeps the radiation in for cooking, it will keep radiation out as well.


Must be sure it is unplugged.... and the cord prongs need to be grounded to a GOOD ground.


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## LincTex (Apr 1, 2011)

TheLazyL said:


> FM radio reception...that answers my question! Thank you for posting the youtube link. I have to find someone that owns a gun safe and see if a FM radio receives when the door is closed.


OK... you have to study the frequencies. Faraday cages can be built to handle different frequencies of RF - -

Referencing using AM/FM/SW radio to test the cage:
JamesH says:
November 28, 2011 at 12:49 pm
"Good start, but the cage is not "impervious even to RF up to only VHF! And there are some more details that you need to take care of. For example, your tests would not detect a lack of attenuation at UHF and higher frequencies that might be caused by gaps or holes in your Faraday shield. But if you pay careful attention to avoid any openings longer than 1/8 inch, that should not be a problem (Someone identified a 1/4 inch limit, and that probably would be adequate, but I tend to be conservative when there is only one chance to get it right.)

The Faraday shield attenuates RF fields. The amount of attenuation depends on the frequency and the thickness and conductivity of the metal in the shield. Copper screen would be better than aluminum because it has better conductivity. (The effect of corrosion over time was not considered in that statement.) The attenuation will be limited because of the thinness of the conductive screen material, though it does increase with increasing frequency. Small hole size screening will definitely provide attenuation to the higher EMP frequencies involved. Do not leave any holes or gaps longer than 1/8 inch in the seams."

Someone suggested covering their solar panels with copper screen, letting some light through. 
James H comments:
"The wires connected to the solar panels will act as antennas producing a very high voltage. You need EMP rated protective breakdown devices connected between the leads to limit that voltage. There voltage rating must be above the maximum possible solar panel generated voltage, but low enough to protect the panels. A high voltage high current rated rectifier diode in series with each lead connected right at the solar panel will improve the protection of the panels. Enclosing the power leads in a metal enclosure along their lengh will also help.

Protect the inverter device in an enclosure and again, protect its output AC power leads with EMP rated voltage limiting devices. Again placing the power leads inside a metal enclosure helps reduce the magnitude of the EMP induced voltage.

A problem is that the* long* pulse, *low frequency* component of the EMP, won't be attenuated by the thin copper of the screen. I don't see an answer to that."


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