September was another in a series of "interesting" months. The month started with a nicely controlled voltage, varying about &plusmin; 1 volt but with a moderately high voltage, averaging almost 124 VAC (123.94 actually). Early on 13 September, the voltage was reduced significantly and thereafter averaged about 121.55 VAC. At the same time, however, the voltage began varying by much more, as much as &plusmin; 3 volts each day. Even with all the voltage swings, the voltage was not often less than the nominal voltage of 120 VAC, and was greater than that about 90.3% of the time during the month. It should of course be greater than 120 only about 50% of the time.
The behaviour of the voltage in September is reminiscent of May 2019.
The histogram above shows the statistical distribution of voltage measurements and the predominance of voltages above the supposed nominal value of 120 VAC (too much voltage).
The diagram above shows all of the voltage measurements according to the time of day when they were taken during September. It seems almost not worth doing this plot of data, because the voltage is so variable that any diurnal pattern of lows and highs during certain periods of the day is lost amid all the variability of the voltage.
See also voltage measurements for other months during 2019.