The IESO will be performing a mandatory voltage reduction test on Tuesday, July 18, as follows:

• 3% test will occur between 09:00 and 10:00 EST 
• 5% test will occur between 13:00 and 14:00 EST

These voltage reduction tests are performed every 18 months, and have been for over 20 years, for the following reasons:

• To determine how much power can be reduced through the two levels of reduction – three and five per cent.
• To identify equipment problems so they can be addressed.
• To help keep IESO and market participant staff familiar with procedures, and identify any deficiencies in the procedures that may need correction.

Voltage reductions have minimal or no noticeable impact on the general public as the voltages are still expected to be within established industry standards for electrical equipment used by residential, commercial and industrial consumers. The service voltage supplied to our customers will remain within the normal operating voltage range during the tests. 

To learn more about Voltage Reduction Testing, please visit Voltage Reductions (ieso.ca).

Full details on the processes around this test can be found in Market Manual 7: System Operations, Part 7.1: System Operating Procedures, Section 7.1: Voltage Reduction Test.