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Corporate IESO > Media > About Public Appeals > IESO Extends Power Warning

IESO Extends Power Warning

August 10, 2005

The Independent Electricity System Operator (IESO) is extending the Power Warning for an additional day, until 8:00 pm tonight.

With the Power Warning, the IESO is asking customers to reduce their use of electricity today to help mitigate the impacts of the current heat wave on Ontario's power system. High temperature and humidity levels combined with continued limitations on supply are continuing to put a strain on the system.

As a result, consumers and businesses are being asked to reduce their electricity consumption between the hours of 8:00 a.m. and 8:00 p.m. today.

Power Warnings are issued by the IESO during periods of high demand for electricity, when supplies of reserve power are low. Any further reduction in transmission or generation availability or any increase in demand could create shortfalls of electricity and require proactive actions such as emergency purchases from other jurisdictions or voltage reduction on the Ontario system.

Consumers and businesses can reduce the demands on the electricity system by:

- Turning off all but essential internal and external lights;
- Setting air conditioners to 26 degrees Celsius or higher, or using fans as an alternative;
- Closing curtains and blinds to keep out the sun and retain cooler air inside; and 
- Delaying the use of major power-consuming equipment such as dishwashers, washers and dryers and swimming pool pumps until after 8:00 p.m.

The IESO is responsible for managing Ontario's bulk electricity system and operating the wholesale electricity market. For more information, visit