The 8 x 20 microsecond waveform is the industry standard current waveform by which surge protection manufacturers design by and test by. It represents the surge energy that is imposed on a power system during a lightning event. Since it is the surge current that a surge protector must pass through it each day (24 hours a day/7 days a week), this is a very important parameter to help you understand the capability of a given protector. Keep in mind that all surges are not exactly 8 x 20 microseconds. Surges on the power line, or in your building wiring, have many different durations and amplitudes. This waveform also gives users an easy apples to apples way of comparing surge protection devices.