I connected up one of my antique Weston AC Voltmeters to monitor my line voltage in my house. My normal line voltage is around 120 +/-2 volts. I've noticed today that it has been varying back and forth in this range due to the drain on the circuits in the neighborhood due to everyone's AC units cycling on and off. I can watch the needle on this meter dip below 120 volts, then bounce back to 122 volts, but most of the time it stays right at 120 volts. I know, I'm nerdy like that!