Originally Posted By: Jeanette_Isabelle
Originally Posted By: AKSAR
I don't wish to rain on anyone's parade. However before spending money on one of these, I would do a bit of research. The website for this product makes a lot of strong claims, with little or no supporting technical data.

Our circle of associates, which includes some well-educated individuals, highly recommends EMP Shield as the only reliable device for its intended purpose.

Jeanette Isabelle
I don't wish to dis your associates. However, regarding EMP protection, the basic physics indicates your associates are mistaken.

Originally Posted By: Jeanette_Isabelle
In simpler terms, should you avoid using EMP Shield and risk having your appliances damaged by an electromagnetic pulse?

Jeanette Isabelle
You need to understand that there are basically two situations that can occur. The first situation is when the source of the EMP is distant from you. In this case, by the time the pulse gets to you, it is two weak to directly damage your devices. However the EMP interacts with the power grid at that distant location. Long conductors like power lines are very susceptible to EMP. The EMP generates a strong voltage/current surge in the power line. In effect the power line acts like a giant antenna, and conducts that surge to you at your distant location. In this case, the EMP Shield might give you a similar level of protection to other commonly available surge protectors that cost half as much or less.

In the second scenario, the sources of the EMP is much closer to you, and the pulse is much stronger. Because it is a "pulse", that means it contains a very wide range of frequencies, from very low to very high. In this case, the EMP can directly damage sensitive electronics. The only way to protect against a strong EMP from a nearby source is to put your device inside a Faraday Shield. This is a conductive shield that completely surrounds the device. However, the design of Faraday Shields is not as simple as some people suggest. In particular, any holes in the shield need to be significantly smaller than the wavelength of the highest frequency you are trying to protect against. Sometimes a "Faraday Cage" can be made out of wire mesh or similar. However, these only protect against wavelengths significantly longer than the size of the openings in the mesh. In this situation of a nearby strong EMP, the EMP Shield wired into your power supply will provide ZERO PROTECTION.

Also keep in mind that in the case of a nearby EMP, say from a nuclear explosion, you probably will have other far more pressing things to worry about than if your appliances still work.

Ultimately, you are free to spend your money however you choose. But in this case the basic physics of the situation indicate that EMP Shield is at best an very overpriced surge protector.
"Toto, I've a feeling we're not in Kansas any more."
-Dorothy, in The Wizard of Oz