He explained the dangers presented by the very power the computer needs to run. That same power can severely damage or even destroy equipment. Sags, also known as brownouts, are short-term decreases in voltage levels and the most common power problem. Electric companies use sags to cope with extraordinary power demands. Hot summer days, when air conditioning requirements are at their peak, will often prompt these brownouts.
Sags also reduce the efficiency and life span of electrical equipment, particularly motors.
Blackouts, which are a total loss of power, are caused by excessive demand on the power grid, lightning storms, ice on power lines, car accidents, back hoes, earthquakes, and other catastrophes. If a blackout occurs while your computer is on, current work in RAM or cache is lost. A spike, also referred to as an impulse, is an instantaneous, dramatic increase in voltage. Like the force of a tidal wave, a spike can enter electronic equipment through AC, network, serial, or phone lines and damage or completely destroy components. Spikes are typically caused by a nearby lightning strike but can also occur when utility power comes back on line after having been knocked out in a storm or as the result of a car accident.