Switch on, switch off

The power goes down about 2-3 times each day. Most people act like nothing has happened. There is only a sudden sigh of silence. Conversations continue, backup power supply kicks in usually within 10 seconds -- and the power and lights are back. Then several minutes later, the same thing happens again, only this time the power is restored and the backup power supply is switched off. During the back up time only the vital resources are kept powered up.