Electromagnetic pulse, or EMP, protection is a process wherein electronics are shielded from possible catastrophic damage resulting from an EMP that is set off nearby. Electronic devices are vulnerable against an EMP due to the fact that the EMP overloads electronic circuitry. This overload can temporarily disrupt electronics or destroy them if the pulse is strong enough. An EMP generates a strong electrical current in electronic devices. If this current is powerful enough, it can damage or destroy the device.
The only true way to protect electronics from an EMP is by constructing a Faraday cage around the electronics. A Faraday cage is a box, bag or other enclosure of any size that is made of a metal mesh. If there is no break in this mesh surrounding an object, any electromagnetic waves that pass through the area cannot penetrate the cage.
A Faraday cage can be built into almost any shape, but the most important facet is that the cage completely surrounds the object that is protected. If wires pass through the cage to the object, if the cage has large gaps in it or it does not encase the electronics inside, an EMP can pass through the cage. For this reason, it is difficult to protect some types of electronics such as the computer modules in cars because it is difficult to completely encase them in a Faraday cage.