Are all enclosures / chassis EMI shielded?

[ITemplate]

Hi,

Are all new chassis / enclosures EMI protected?

For example I'm looking at this from Antec: Three Hundred or the P180 but it says nothing about EMI shielding - are they shielded you think?

--
Werner

 

[Outlander_04]

none are shielded specifically AFAIK

but an enclosed metal case will be a Faraday Cage

 

[ITemplate]

none are shielded specifically AFAIK

but an enclosed metal case will be a Faraday Cage

Ok, however I cant imagine that they act like faraday cages since there are large holes all over. Unfortunately the only enclosures I have found which claims EMI protection are from Asus...

 

[Outlander_04]

a mesh cage is still a faraday cage

so long as its grounded though the power supply earth then I doubt any case is better than any other and claiming it is is more marketing than technology

 

[ITemplate]

a mesh cage is still a faraday cage

so long as its grounded though the power supply earth then I doubt any case is better than any other and claiming it is is more marketing than technology

Ok that sounds like an important advice. I havent yet installed the electrical wires where this sever must be placed. I should make sure they are grounded.

About faraday cages you might be right, but I was always under the impression that any holes in a farady cage must be smaller than the wavelength of the poluting radiation. And the mesh in those enclosures sure are a tad larger than any wavelength I know of

Thanks for your input.

 

[cjl]

Well, 1GHz EM has a wavelength of 30CM, which is quite a bit larger than any of the holes in either of the cases you mentioned. 10GHz is still 3cm, which still seems bigger than any of the holes in those cases, so I think you're fine (unless you're talking about pretty high frequency EM here).

 

[ITemplate]

Well, 1GHz EM has a wavelength of 30CM, which is quite a bit larger than any of the holes in either of the cases you mentioned. 10GHz is still 3cm, which still seems bigger than any of the holes in those cases, so I think you're fine (unless you're talking about pretty high frequency EM here).

I stand corrected, never did investigate the wavelengths in practical appliances like radio etc. Didnt know they were that much longer than for example microwaves and such...

But that's excellent. It means that I can get that lovely Antec enclosure

 

[Paperdoc]

Regarding wavelengths and frequencies, 1 GHz and 10 GHz are microwave frequencies. Typical microwave ovens run around 1 to 2 GHz. The "microwave" range covers roughly from 1 to 100 GHz. Above 100 GHz is the lower end of the far-infrared frequency region. Below 1 GHz is regarded as the high-frequency end of RF; UHF radio and TV uses frequencies up to about 800 MHz.

Wavelength in cm = 30 / frequency in GHz; hence the numbers cjl gave you.

Regarding EMI shielding any computer certainly has quite a bit of shielding. It is required for compliance with government regulations (FCC in the USA) limiting the amount of EM noise that can be radiated OUT from a device, to avoid having it interfere with other nearby devices. Thus, it also has some protection of itself from external sources. It's not perfect, of course. The metal components of the case or its interior structure play a role here. But even the plastic case exteriors, surprisingly, are part of the shielding. A very important development a couple of decades ago was a way to spray an electrically conductive coating on the inside of plastic cases so that they behave as EMI shielding cases, eliminating the need to use metal for all of the case.

Outlander_4 is quite correct - it only works if the case is grounded to provide a placed for the EMI currents to flow with near-zero impedance. You indicate you are installing the electrical supply wiring yourself. I don't know what you have in mind. If it's in-the-wall cables and outlets, in North America you will HAVE TO install wiring that includes a bare copper Ground or "Bonding" lead connected to both the metal device box mounted in the wall, and the Ground terminal of the electrical outlet. The three-wire plug on your computer case then connects your case to that Ground through the green wire in the cord. If, instead, you plan to run just some extension cord from a wall outlet elsewhere, you MUST make sure you use a 3-wire cord with Ground.

If you have 3-prong grounded outlets in your house, just using the 3-wire cords etc is sufficient. If you have no Grounds in your house wiring you have a different set of problems. For that, see my post here:

http://www.tomshardware.com/forum/264400-28-poor-electrical-ground

 

[mj39569]

I think emi shielding have made changes in human life.it gives more security to their users.
http://www.effshield.com

 

[mj39569]

Emi shielding is the best way to change the life of the people.It is a secure way to do anything.

 

[an0nymous]

Up!

How much such case/tower?

Ebay are empty, where to get one?