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Corporate IESO > Media > About Public Appeals > IESO Appeals for Reduced Electricity Consumption as Hot Weather Strains System

IESO Appeals for Reduced Electricity Consumption as Hot Weather Strains System

July 18, 2005

The Independent Electricity System Operator (IESO) is asking consumers to reduce their use of electricity for the remainder of the week as record hot weather continues to put a strain on Ontario's electricity system.

"The heat wave is presenting a number of challenges for the IESO in managing the reliability of the electricity system," said Paul Murphy, Chief Operating Officer for the IESO. "The sustained hot weather is resulting in record demands for electricity and places operating limitations on both generation and transmission facilities. In addition, a near drought in much of Ontario has resulted in decreased supply from hydroelectric generating facilities."

As a result, consumers and businesses are being asked to reduce the electricity consumption, where possible, between the hours of 8:00 a.m. and 10:00 p.m.

"Higher consumption will mean higher electricity bills - any conservation efforts will not only help individual consumers to offset those higher costs, but will help us to maintain reliable service to all consumers," added Murphy.

The voluntary appeal for reduced consumption is in effect until 6:00 p.m. Friday, July 22. However, more immediate stronger appeals such as a Power Warning or Power Emergency may be issued if the situation deteriorates.

The IESO issues a Power Advisory when supplies of power, including imports, are forecast to be adequate, but the expected high demand will put a prolonged strain on the electricity system. Conservation measures will benefit consumers, the environment and the electricity infrastructure. Power Advisories can last for an extended period of time.

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 retaining cooler air inside; and 
- Avoiding or limiting the use of major power-consuming equipment such as dishwashers, washers and dryers and swimming pool pumps between the hours of 8:00 a.m. and 10:00 p.m.

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