November was a rather mundane continuation of October until 10:00 a.m. on 29 November when the voltage suddenly increased by about 4 VAC. Up to that time the average for the month had been just under 121.5 volts, but afterward the average was 125.77 VAC and at one point reached 129.1 volts. Overall, the voltage has been greater than the nominal 120 VAC about 77.6% of the time, based on 4,245 measurements.
The histogram above shows the statistical distribution of voltage measurements and the "long tail" of voltages above the supposed nominal value of 120 VAC.
The diagram above shows all of the voltage measurements according to the time of day when they were taken during November. The higher voltage measurements after 10:00 a.m. on 29 November can be seen scattered above the main body of other measurements before that time.
The diagram below shows the average voltage at time of day during the month but before the dramatic change of voltage at 10:00 a.m. 29 November.
See also voltage measurements for other months during 2019.