Building a Faraday cage with a conductive cloth and magnets

[bibei]

TL;DR Summary

Building a faraday cage with a conductive cloth and magnets.

Hi,

I want to build a faraday cage and use a metal box for it (like a metal cabinet, a big tin box, a metal basket or even an old safe or something like that. As these objects have small holes or gaps, some people say you need to put conductive tape on them to close these gaps. That is not very convenient as you want to be able to open and close these boxes every day to put stuff inside or take it out. So someone suggested to cover the gaps with a conductive cloth and stick the cloth to the box with magnets. So far so good, but my question would be: does the cloth have to touch blank metal from the object (as they are painted) or is attaching it with magnets on painted metal good enough to get premium shielding?

 

[gmax137]

@bibei , see the wiki page "faraday cage" It explains the effect of the mesh size.

 

[berkeman]

Welcome to PF.

I want to build a faraday cage and use a metal box for it (like a metal cabinet, a big tin box, a metal basket or even an old safe or something like that.

What is the application? What frequencies do you need to shield for? How much attenuation do you need? What kind of feed-throughs do you need to build into this enclosure? (power, signals, other?)

There are a number of important things to get right when building a shielded enclosure with an access port. Once we know the application and the other things I asked about above, we can probably help you make a reasonable enclosure. In the mean time, here are some links to useful info:

https://www.ets-lindgren.com/support/articles-whitepapers?page=Articles-WhitePapers-Page

https://leadertechinc.com/enclosure...ajroTWWt3dwe3pIQap653Dp1jEqFsakUaAqKQEALw_wcB

 

[bibei]

Hi, Thank you for the answers. I am trying to harden an electronic safe at our school against emp. That is the main reason. Thank you for your advice and I'll have a look at your sources.

 

[berkeman]

Hi, Thank you for the answers. I am trying to harden an electronic safe at our school against emp.

Um, do you expect a tactical nuke to be detonated nearby soon, or are you trying to make it harder to disable the safe with an external ESD/EMI event? Is it a standard product? If so, does the manufacturer have suggestions on how to harden it? Does it have a CE Mark on it?

 

[bibei]

I need to check the product and have a look. But I expect it not to be EMP proof, it probably has a CE mark as it is a 'quality' product. I don't hope for anything bad, but times are not what they used to be unfortunately.

 

[berkeman]

I don't hope for anything bad, but times are not what they used to be unfortunately.

And what in this school safe is worth a thousand Euros to protect? And if there is an invasion in your area and tactical nukes are employed, who will be left to open the safe?

 

[bibei]

And what in this school safe is worth a thousand Euros to protect? And if there is an invasion in your area and tactical nukes are employed, who will be left to open the safe?

we could not run the school anymore as it contains a lot of stuff from the administration. Ok, on the risk of sounding dramatic (i actually hope it is just my dramatic scenario) a worst possible case would be a 'problem' 900 kilometers away, actually there are problems the last few years at that distance of our school.

 

[berkeman]

we could not run the school anymore as it contains a lot of stuff from the administration.

If there is an EMP that could damage the safe, it would damage every other piece of electronic equipment in the school. Do you have paper copies of everything that you need in that safe? That is all that you will be able to use.

 

[bibei]

If there is an EMP that could damage the safe, it would damage every other piece of electronic equipment in the school. Do you have paper copies of everything that you need in that safe? That is all that you will be able to use.

that is a valid point

 

[berkeman]

After a PM conversation, this thread is now tied off.