A blackout is a total loss of electrical power. A blackout is usually defined as a drop in line voltage below 80 volts (V) (the normal voltage is 120V), since most electrical equipment will not operate below these levels. A blackout may be due to a planned interruption, such as limiting of loads during power shortages by rotating power shutoffs through different areas, or due to an accidental failure caused by human error, a failure of generating or transmission equipment, or a storm. Blackouts can cause losses of industrial production, disturbances to commercial activities, traffic and transportation difficulties, disruption of municipal services, and personal inconveniences. In the summer of 1977, a blackout caused by transmission line losses during a storm affected the New York City area. About nine million people were affected by the blackout, with some areas without power for more than 24 hours. The blackout was accompanied...