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#299015 - 05/25/21 01:51 PM Re: EMP [Re: brandtb]
chaosmagnet Offline
Sheriff
Carpal Tunnel

Registered: 12/03/09
Posts: 3819
Loc: USA
An old microwave might work okay.

Quick test for the non-radio-inclined: Connect to your phone with a Bluetooth headset or similar device. Unplug the old microwave (so that no matter what happens, it doesn't get turned on during the next part). Put the phone in the microwave and close the door. If your Bluetooth device still works, it's not a great Faraday cage.

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#299018 - 05/25/21 04:12 PM Re: EMP [Re: Famdoc]
adam2 Offline
Addict

Registered: 05/23/08
Posts: 474
Loc: Somerset UK
I would favour TWO layers of metallic protection, this need not be expensive or elaborate.
I use metal tins that previously contained biscuits, and these tins placed inside a metal filing cabinet.

Items that I store include

Two way radios.
Radio receivers.
Geiger counters.
LED light bulbs, various types including flashlight bulbs and vehicle bulbs.
LEDs, bare components not LED lamps.
Silicon rectifier diodes.
Electrical test meters.

Cellphones and PCs are in my view a lower priority as cellphone service is unlikely to be available, nor is an internet connection or enough power to work a PC likely to be available.

Zinc carbon batteries should survive just fine as should alkaline types and lead acid batteries.
Any more modern type of battery that incorporates electronics will probably be killed by an EMP.

It is worth storing the materials to make basic batteries, the raw materials keep forever and are invulnerable to an EMP.

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#299019 - 05/25/21 09:01 PM Re: EMP [Re: Famdoc]
chaosmagnet Offline
Sheriff
Carpal Tunnel

Registered: 12/03/09
Posts: 3819
Loc: USA
The most critical components of a Faraday cage are continuous conductive material around whatever you're putting inside it and an insulation layer (a layer of cardboard will do, plastic or air works well too). There's a school of thought that suggests another layer of continuous conductive material on the outside, insulated from the inner layer. Any devices being protected should not touch any of the conductive material.

A large steel toolbox (often called a "job box") could work as the outer layer, although I'd be careful to make sure that the lid was tightly fitted and well-connected electrically to the main body.

My expectation is that something like a Carrington Event would damage or destroy large electrical grid transformers, along with anything else connected to long conductive wires. Smaller grid transformers connected to shorter wires may or may not be affected. Based on what I've read -- I'm certainly not an expert -- complex electronics within cars and small devices are more likely to survive than not.

Certainly, a close, strong EMP would damage or destroy almost any electronic device.


Edited by chaosmagnet (05/25/21 09:04 PM)

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#299020 - 05/26/21 12:05 AM Re: EMP [Re: chaosmagnet]
adam2 Offline
Addict

Registered: 05/23/08
Posts: 474
Loc: Somerset UK
Originally Posted By: chaosmagnet
The most critical components of a Faraday cage are continuous conductive material around whatever you're putting inside it and an insulation layer (a layer of cardboard will do, plastic or air works well too). There's a school of thought that suggests another layer of continuous conductive material on the outside, insulated from the inner layer. Any devices being protected should not touch any of the conductive material.

A large steel toolbox (often called a "job box") could work as the outer layer, although I'd be careful to make sure that the lid was tightly fitted and well-connected electrically to the main body.

My expectation is that something like a Carrington Event would damage or destroy large electrical grid transformers, along with anything else connected to long conductive wires. Smaller grid transformers connected to shorter wires may or may not be affected. Based on what I've read -- I'm certainly not an expert -- complex electronics within cars and small devices are more likely to survive than not.

Certainly, a close, strong EMP would damage or destroy almost any electronic device.


I very largely agree, except that I see no need for an inner insulating layer. All parts of a Faraday cage will be at the same voltage and it matters not if the contents touch the inner walls.

A steel "job box" would give a good degree of protection but I would still prefer a second inner container as a second line of defense in case the hinged lid of the outer box gives imperfect protection.

These job boxes are often used to protect expensive tools against theft. Much better than a trash can in this respect. Security is good, no point in protecting supplies against EMP if a thief takes them instead.

A utility transformer connected to long power lines would probably be destroyed by a Carrington event and would almost certainly be destroyed by an EMP.
A spare utility transformer in the power companies stores and not connected to anything should survive a Carrington event.
A spare utility transformer in storage MIGHT survive an EMP if prepared by connecting all input and output connections to each other and to the steel tank. The tank IS a reasonable Faraday cage and connecting each end of each winding to the tank SHOULD prevent damage. Utility transformers are designed to withstand much greater voltages than domestic electronics.

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#299021 - 05/26/21 03:43 AM Re: EMP [Re: adam2]
Blast Offline
INTERCEPTOR
Carpal Tunnel

Registered: 07/15/02
Posts: 3760
Loc: TX
The inside of my metal trash can is lined with a blue, closed-cell sleeping pad so nothing touches the metal. It still needs a better air-gap seal, though.
-Blast
_________________________
Foraging Texas
Medicine Man Plant Co.
DrMerriwether on YouTube
Radio Call Sign: KI5BOG
*As an Amazon Influencer, I may earn a sales commission on Amazon links in my posts.

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#299023 - 05/26/21 01:38 PM Re: EMP [Re: adam2]
chaosmagnet Offline
Sheriff
Carpal Tunnel

Registered: 12/03/09
Posts: 3819
Loc: USA
Originally Posted By: adam2
I very largely agree, except that I see no need for an inner insulating layer. All parts of a Faraday cage will be at the same voltage and it matters not if the contents touch the inner walls.


I don't think that's correct. I think that when an electronic device touches the conductive layer, that layer stops being a Faraday cage and starts being an antenna.

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#299081 - 06/08/21 03:49 PM Re: EMP [Re: chaosmagnet]
brandtb Offline
Addict

Registered: 11/26/04
Posts: 500
Loc: S.E. Pennsylvania
Originally Posted By: chaosmagnet
Originally Posted By: adam2
I very largely agree, except that I see no need for an inner insulating layer. All parts of a Faraday cage will be at the same voltage and it matters not if the contents touch the inner walls.


I don't think that's correct. I think that when an electronic device touches the conductive layer, that layer stops being a Faraday cage and starts being an antenna.


Would one of those 5- or 6-mil 'contractor' trash bag act as an insulator?


Edited by brandtb (06/08/21 03:49 PM)
_________________________
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#299083 - 06/08/21 06:34 PM Re: EMP [Re: brandtb]
chaosmagnet Offline
Sheriff
Carpal Tunnel

Registered: 12/03/09
Posts: 3819
Loc: USA
Originally Posted By: brandtb
Would one of those 5- or 6-mil 'contractor' trash bag act as an insulator?


I expect it would work.

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