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2019 Archive of Measurements of Electrical Voltage Delivered to My Home

Graphical Monthly Summaries of My Voltage Measurements

What follows are separate charts for each month of 2019 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, Ontario.  The months are in reverse chronological order.

If you have questions or comments about any of the information here, please contact me

August 2019

History of voltage during August 2019

Well, similar to July, the month of August was kind of craxy.  The average voltage over the month was 125.12 VAC and there were 5 days when the voltage seemed almost out of control : 9, 10, 11, 18, and 19 August.  At one time, the voltage reached 130.2 VAC.  The only hopeful sign during the month was that for the last two days (30 and 31), the voltage seemed to have dropped by two volts. 

Crazy voltages at my house during August 2019

Above is a graph of the voltages on the five days with crazy voltage behaviour.  The only pattern that I see here is that the voltage was highest during the early morning hours, similar to most days in other months, except that these voltages were especially, even dangerously, high.  One wonders what is going on at Hydro One and their generating stations during these periods.  Can someone explain, please??

Histogram of voltage measurements, August 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 voltage should be above and below the nominal voltage 50% of the time each.  Clearly it is not. 

Average Voltage at Time of Day during August 2019.

Looking at the Average Voltage at Time of Day diagram above shows the general trend of voltage being moderately higher at night and lower during the daylight hours of each day. 

Voltage at Time of Day during August 2019.

The diagram above shows all of the voltage measurements according to the time of day when they were taken during August. 

And What Does This Extra Voltage Cost?

We know that the power dissipated, and energy consumed, by a resistive load (like your toaster, hair-dryer, clothes-dryer, etc.) is proportional to the square of the voltage.  So we can compare these house voltages with the power dissipated when only 120 VAC is applied and find the extra power that is dissipated and that we have to pay for.  The graph below shows this extra cost according to the average voltage at any time of day during August.  It amounts to between 7 and 10% above what we would have been charged if the voltage had been only 120 VAC, which is of course the voltage that we should have received from Hydro One. 

Cost of extra voltage during any day in August 2019

July 2019

History of voltage during July 2019

The month of July was just crazy.  There were three very different "voltage behaviours" during the month.  First, and until 17 July, the voltage was well-behaved with an average very near the nominal voltage of 120 VAC.  This was good.  Then, around 3:30 p.m. on 17 July the voltage was suddenly increased by about 5 VAC, from 117 to 122 VAC, and with the voltage never going below 120 VAC.  Then, superimposed on this new, higher voltage, there were six days when the voltage appeared to be out of control, rising at times above 130 VAC and as high as 132.6 VAC.  Overall, the average voltage for the month was 121.96 VAC, and was greater than the nominal 120 VAC 67.2% of the time, based on 4,460 measurements. 

Crazy voltages at my house during July 2019

Above is a graph of the voltages on the six days with crazy voltage behaviour.  The only pattern that I see here is that the voltage was highest during the early morning hours, similar to most days, except that these voltages were especially, even dangerously, high.  One wonders what is going on at Hydro One and their generating stations.  Can someone explain, please??

Voltage versus temperature for latter part of July 2019

So, are the high temperatures causing these wild voltage variations?  It seems so.  Although the data sample is small (only 14 days), the chart above does show that when the daily maximum temperature is 27° C or less, the voltage is well-behaved.  When the maximum temperature is above 27° C, there is a good chance (6 times out of 11) that the voltage will misbehave and go to 130 VAC or above. My guess is that there is some errant computer algorithm that makes inconsistently bad decisions when the outside temperature is 27° C or above.  Or, maybe it is just some nervous supervisor at Hydro One?  It is curious that the "bad" days seem to have come in pairs. 

Histogram of voltage measurements, July 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 voltage should be above and below the nominal voltage 50% of the time each.  Clearly it is not. 

Average Voltage at Time of Day during July 2019.

Looking at the Average Voltage at Time of Day diagram above shows the general trend of voltage being higher at night and lower during the daylight hours of each day.  But this chart is almost meaningless because it is comprised of data from before 17 July when the voltage was well-behaved, data afterwards when the voltage was generally higher by 5 volts, and data from the six days when the voltage was out of control. 

Voltage at Time of Day during July 2019.

The diagram above shows all of the voltage measurements according to the time of day when they were taken during July.  You can easily see how confused the data is, as described above.

June 2019

History of voltage during June 2019

The month of June was a continuation of the trend begun during May, and the delivered voltage has continued to decrease slowly.  The average voltage for the month was 121.31 VAC, although still with more hour-to-hour variability than expected.  The voltage was greater than the nominal 120 VAC about 76.8% of the time, based on 4,317 measurements. The chart above shows the how the voltage varied during the month. 

Histogram of voltage measurements, June 2019.

The histogram above shows the statistical distribution of voltage measurements and the predominance of voltages above the supposed nominal value of 120 VAC.  The voltage should be above and below the nominal voltage 50% of the time each.  Clearly it is still not, although this situation is improving. 

Average Voltage at Time of Day during June 2019.

Looking at the Average Voltage at Time of Day diagram above shows the general trend of voltage being higher at night and lower during the daylight hours of each day.  Comparing this chart with those for several previous months, one can see how the average voltage is approaching the nominal voltage of 120 VAC. 

Voltage at Time of Day during dJune 2019.

The diagram above shows all of the voltage measurements according to the time of day when they were taken during June.  The general tendency for the voltage to be higher at night than during the day is still visible in this chart.

May 2019

History of voltage during May 2019

The month of May began as a continuation of the last week of April, but around 8:00 a.m. on Saturday, 11 May, Hydro One lowered the average voltage by about 2 VAC and the measurements continued thereafter with much greater variability than before.  Before this change the voltage had been greater than the nominal 120 VAC 100% of the time, but afterwards the voltage was so variable that it was greater than the nominal 120 VAC only about 85% of the time.  The chart above easily illustrates this change in behaviour.  Overall, the average voltage for the month was 122.28 VAC, based on 4,461 measurements. 

Histogram of voltage measurements, 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.  The voltage should be above and below the nominal voltage 50% of the time each.  Clearly it is not.

Average Voltage at Time of Day during May 2019.

Looking at the Average Voltage at Time of Day diagram above shows the general trend of voltage being higher at night and lower during the daylight hours of each day. 

Voltage at Time of Day during May 2019.

The diagram above shows all of the voltage measurements according to the time of day when they were taken during May.  The wide variability of the voltage delivered to my home since the change on 11 May now obscures the general trend for higher voltages during the night.

April 2019

History of voltage during April 2019

The beginning of April 2019 saw a continuation of the last several months.  However, following two power outages of several hours on 20 April, the restored voltage was remarkable for two reasons : the voltage was now better regulated (that is, less variable during each day), and now averaged about one volt higher than before the outage, and 4 VAC above the nominal voltage of 120 VAC.  The average voltage during April overall was 123.64 VAC, based on 4,275 measurements taken once each 10 minutes.  The voltage was greater than the nominal 120 VAC a whopping 99.5% of the time, as you can see from the charts above and below.  The change in behavior after the power outage on 20 April is also evident in the chart above. 

Histogram of voltage measurements, April 2019.

The histogram above shows the statistical distribution of voltage measurements and the predominance of voltages above the supposed nominal value of 120 VAC.  The voltage should be above and below the nominal voltage 50% of the time each.  Clearly it is not.

Average Voltage at Time of Day during March 2019.

Looking at the Average Voltage at Time of Day diagram above shows the general trend of voltage being higher at night and lower during the latter part of each day. 

Voltage at Time of Day during April 2019.

The diagram above shows all of the voltage measurements according to the time of day when they were taken.  The voltage was "well-behaved" in the sense that there were few times when the voltage strayed from this rather well-defined band of observed voltages.  Our conclusions about the variation of voltage gained from the histogram are also confirmed.

March 2019

History of voltage during March 2019

March 2019 saw a continuation of the last several months with no significant changes — the "usual" situation of delivered voltages significantly greater than the nominal voltage of 120 VAC.  The average voltage during March was 123.24 VAC, based on 4,455 measurements taken once each 10 minutes.  The voltage was greater than the nominal 120 VAC a whopping 99.28% of the time, as you can see from the charts above and below.  Remarkably, early one day, the voltage went as high as 127.9 VAC. 

Histogram of voltage measurements, March 2019.

The histogram above shows the statistical distribution of voltage measurements and the predominance of voltages above the supposed nominal value of 120 VAC.  The voltage should be above and below the nominal voltage 50% of the time each.  Clearly it is not.

Average Voltage at Time of Day during March 2019.

Looking at the Average Voltage at Time of Day diagram above shows the general trend of voltage being higher at night and lower during the latter part of each day. 

Voltage at Time of Day during March 2019.

The diagram above shows all of the voltage measurements according to the time of day when they were taken.  The voltage was "well-behaved" in the sense that there were few times that the voltage strayed from this rather well-defined band of observed voltages.  Our conclusions about the variation of voltage gained from the histogram are also confirmed.

February 2019

History of voltage during February 2019

February was a continuation of January 2019 with no significant changes   the "usual" situation of delivered voltages significantly greater than the nominal voltage of 120 VAC.  The average voltage during February 2019 was 122.83 VAC, based on 4,004 measurements taken once each 10 minutes.  The voltage was greater than the nominal 120 VAC a whopping 96.88% of the time, as you can see from the charts above and below. 

There was a power outage of approximately 2½ hours early on 25 February, probably due the the very windy weather, after which the voltage continued as before. 

Histogram of voltage measurements, February 2019.

The histogram above shows the statistical distribution of voltage measurements and the predominance of voltages above the supposed nominal value of 120 VAC.

Voltage at Time of Day during February 2019.

Looking at the Voltage at Time of Day diagram above shows the general trend of voltage being higher at night and lower during the latter part of each day.  The voltage was "well-behaved" in the sense that there were few times that the voltage strayed from the rather well-defined band of voltages that were observed at any time during the day or night. 

January 2019

History of voltage during January 2019

January was a continuation of the last half of December 2018 and a return to the "usual" situation of delivered voltages significantly greater than the nominal voltage of 120 VAC.  The average voltage during January 2019 was 123.12 VAC, based on 4,460 measurements taken once each 10 minutes.  The voltage was greater than the nominal 120 VAC a whopping 98.66% of the time, as you can see from the charts above and below. 

Histogram of voltage measurements, January 2019.

The histogram above shows the statistical distribution of voltage measurements and the predominance of voltages above the supposed nominal value of 120 VAC.

Voltage at Time of Day during January 2019.

Looking at the Voltage at Time of Day diagram above shows the general trend of voltage being higher at night and lower during the latter part of each day. 

Got Data?

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. 

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