The Independent Electricity System Operator (IESO) will conduct a routine voltage reduction test on Thursday, July 23, 2026, as part of mandatory testing of its emergency operating procedures. This province-wide test will have minimal noticeable impact on the public at large.
The test will consist of two reductions in voltage:
- A three per cent voltage reduction will occur from 9:00 – 10:00 ET
- A five per cent reduction from 13:00 – 14:00 ET
These tests are normally conducted every 18 months, and have been for more than 20 years. If you did not notice any impact during past tests, you should not notice it during this test.
Ensuring a reliable grid
Voltage reduction is one tool that the IESO could use to help maintain the reliability of Ontario’s power system in an emergency situation. Voltage reduction tests are done for the following reasons:
- To identify any equipment problems or other material concerns among voltage reduction test participants caused by reduced voltage; and
- To measure the total amount of load reduction that is attainable for each exercise.
For more information
The IESO is responsible for managing Ontario’s bulk electricity power system and operating the wholesale market. More information about their services can be found at ieso.ca.
Additional information about the voltage reduction test can be found on the IESO’s website at ieso.ca/en/Sector-Participants/System-Reliability/Voltage-Reductions.
If you have questions about the test, please contact our Customer Care team by phone at 226-896-1010 or by email at customercare@enovapower.com.
