Reminder: Routine Voltage Reduction Tests Scheduled for July 23
July 17, 2026
Routine voltage reduction tests will take place on Thursday, July 23 as part of mandatory testing of the IESO’s emergency operating measures. The tests are an important verification for ensuring the reliability of Ontario’s electricity grid.
A three per cent reduction is expected to occur from 9 to 10 a.m. EST. A five per cent reduction is planned for 1 to 2 p.m. EST.
Voltage reductions have minimal or no noticeable impact on the public as the voltages are still expected to be within established industry standards for electrical equipment used by residential, commercial and industrial consumers.
If system conditions are not favourable on July 23, the alternate test date is scheduled for Thursday, July 30.
More information about voltage reduction tests is available on the IESO's website.