Graphical Details of My Monthly Voltage Measurements
What follows are separate charts for each month showing the thousands of voltage measurements I have made at my wall outlet of the too much voltage delivered to my home and appliances by Hydro One. The charts include a time series diagram (history), a statistical histogram of the voltage during the month, and a scatter diagram of voltage versus the time of day, for each month beginning December 2015.
A general summary of all my measurements, with some up-to-date interim data for the current month, can be found here. The monthly details below are presented in reverse chronological order, that is, most recent months first.
If you have questions or comments about any of the information here, please contact me.
Voltages at my home moderated somewhat during July, averaging about 122.1 VAC. Despite several spells of very warm weather, the range of voltages seen did not increase from previous months. The average voltage is still higher than I would prefer.
Voltages were significantly higher this month than they have been, in fact, highest since the end of that terrible (voltage-wise) winter of 2015-16. The recent increasees definitely look like a trend! See the chart on the summary page.
Voltages seem a little higher this month. I hope it isn't the start of a trend.
Voltages during April were about the same as during March, helping to establish a definite levelling off of the voltage supplied by Hydro One. It will be interesting to see if this level of voltage can be maintained during the coming summer months when the system is stressed by the impacts of hot and humid weather.
March showed a slight relaxation in the trend to a higher average voltage and the average voltage seems now to be stable at a value between 121 and 122 VAC. Sure wish they had done this during the winter of 2015/16! As noted in February, the difference in voltage between day and night is much less now than before.
February saw a continuation of the trend to rising voltages since last summer. The average voltage is still less than 122 VAC but not by much (121.86 VAC). I suppose that Hydro One hopes that I will become bored and stop watching them. (As a confirmed data junkie, I am unlikely to do that!). Curiously, the day/night difference is much less clear now than before (see the Time of Day scatter diagram).
Voltages observed during January 2017 were much better behaved than a year ago and were almost normal by comparison, averaging near 121 VAC instead of 124 VAC. Whether this was due to some new customer-friendly policy at Hydro One or was dictated by some technical circumstance of supply and demand, I do not know. Compare the three charts below with those for January 2016, further down.
Voltages during December continued higher than during the last summer but not as high as one year ago, during the winter of 2015-2016.
Voltages during November were again higher than the previous month, but not yet as high as during last winter.
Voltages during October were somewhat higher than during the summer, perhaps due to the lower load on Hydro One's supply system (less air-conditioning and still not much need for heating). The average voltage is no longer near 120.0 volts AC.
The lower voltage situation seen in July and August continued in September. These voltages are very kind to my appliances and my Hydro bill, and I hope they will continue.
The lower voltage trend set in July continued during August. You could see on the hottest days how much lower the voltage was than on cooler days. There was a small but significant increase in average voltage around the 13th of August which continued for the rest of the month. Overall, from the point of view of a residential customer, the average voltage was quite acceptable, and the lowest and highest voltages were also very acceptable. Let us hope that this continues for some time.
What a difference a month makes! Big changes! Over a period of several days beginning on 02 July, the delivered voltage was brought down to around 119 VAC, even lower that it needs to be. By the end of July, the average voltage at my home was between 119 and 120 VAC. The diagram of voltage history, below, clearly shows the change at the beginning of the month and the subsequent lower average voltage compared to previous months since the beginning of July. Due to this almost dramatic change I felt it necessary to take more measurements (385) than usual and, with this added "density of data", the daily shift in voltage is very evident in the Time of Day diagram, showing how the voltage is generally higher late in the evening and overnight and lower during the daylight hours. As well, the wider range of voltages encountered during July shows clearly in the histogram. Compare these three diagrams with those for earlier months to see the changes. The present situation with probably continue until the fall when the average voltage will rise again.
June was a continuation of recent months with an average voltage around 122.5 VAC (still significantly higher than the nominal 120 VAC it is supposed to be) and with less variation than during the winter months (see especially January and February below).
As indicated last month, Hydro One has now moved to their 'summer voltage program', with a somewhat lower voltage than in the winter and with less variation in the voltage. However, the average voltage at my wall outlets is still almost 2% higher than it needs to be and only occasionally dips below the nominal voltage of 120 VAC. Two percent might seem small, but it adds up over time. So, I am still paying for more electrical energy than my appliances need.
A definite change has occurred! As they do most years in the spring, Hydro One has lowered the voltage. During April, the average voltage at my home fell to under 123 VAC instead of being over 124 as it was during the winter. On one occasion I measured a voltage less than 120 VAC (actually 119.7). As shown in the "history" chart, the voltage seems now to be more steady with less variation. Of course, next fall the voltage will go back up again, as it does every fall.
Results for the month of March indicate much the same situation as in previous months, although there has been a small reduction in the average voltage being delivered, about half a volt. What is needed, however, is a reduction of at least four volts, so this small change is of little practical value to rural customers. There was also a period of unusual stability of voltage, around 122-124 VAC, during 16-17 March (a Wednesday and Thursday), but the variation in voltage soon returned to normal after that.
During February 2016 the voltage at the wall outlets of my home was measured 283 times and the average was about the same as during December and January. As before, the highest voltage was over 127 VAC.
During the month of January 2016, I measured the voltage at my wall outlets 238 times. The average was about the same as during December and the highest voltage measured was 127.7 VAC, again just within the range defined by the CSA as "extreme operating conditions".
During the month of December 2015, I measured the voltage at my wall outlets 135 times, spread more or less randomly during the days and nights of the month, using a reasonably accurate digital multimeter and checked by comparison with others. The measurements had a spread of 121.0 to 127.2 VAC, and a calculated mean (average) of 124.25 VAC.
As expected from the calculated average (124.25 VAC), the peak in the histogram is between 124 and 125 VAC. As shown in the "Time of Day" graph, the voltage tends to be higher late in the evening and over night, and somewhat lower during the day. This tendency continued in the following months, as shown in the graphs above.
If you have voltage measurements from your own neighbourhood and would like to share them, please contact me and I would be glad to exchange raw data and other results with you.Back to Top