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Electricity transmission in Canada

Canada’s bulk transmission network consists of more than 160,000 kilometres of high voltage lines. This is enough to cross the entire country roughly 27 times.

These lines carry electricity at voltages above 50 kilovolts to move electricity in bulk over long distances. Because of Canada’s vast geographic size, its electricity systems require different types of high voltage lines (typically at 115 kilovolt, 230 kilovolt and 500 kilovolt levels) to deliver electricity safely, reliably and economically to customers.


Most of Canada’s provinces and territories are part of interconnected electricity “grids,” networks of power plants, substations and transmission lines that cross international, provincial and territorial borders. These networks provide electric utilities with alternative power paths in emergencies, and allow them to buy and sell power from each other and from other power suppliers.

Canada has three power grids: the Western grid, the Eastern grid, and the Quebec grid, which includes Atlantic Canada. The border between the Eastern and Western grids is the Alberta-Saskatchewan border. Canadian grids are also tied into the U.S. grids (the Western Interconnection, the Eastern Interconnection and the Texas Interconnection). For example, the electricity grid in Alberta and British Columbia is part of the Western Interconnection in the United States.

North-south pattern

There is a predominantly north-south pattern to Canada’s transmission high voltage lines. This has emerged over time as utilities develop generation sites in northern areas of the country to produce and transmit electricity to urban markets in the south. Hydro-Québec’s system, for example, extends more than 1,100 kilometres from Churchill Falls in Labrador to Montreal, and from James Bay to southern load centres, which include U.S. markets. In Manitoba, a large 500 kilovolt DC system brings hydropower from the Nelson River to customers in the Winnipeg area. In Ontario and British Columbia, major 500 kilovolt systems bring electric power from northern generating sites to markets in the south.


Transmission lines in a given area may be owned by a single company or by a number of different companies. Similarly, the generation and the distribution facilities the transmission lines connect can be owned by the same company, or by different companies.

In most provinces and territories, vertically integrated, government-owned utilities look after the planning, building and operation of transmission as part of their bundled services. Some provinces, however, are undergoing fundamental changes that have restructured their markets and unbundled generation, transmission and distribution services. The pace of this change is occurring at different rates across the country. The extent of this restructuring varies because regulation of the electricity industry is generally the responsibility of the provinces and territories.

In provinces such as Ontario and Alberta, vertically integrated utilities have been divided into separate generation, transmission and distribution companies. In 1999, Ontario Hydro was split into a number of successor organizations, including Ontario Power Generation and Hydro One. The former manages generation plants, and the latter owns and operates the province’s transmission system. This change is most advanced in Alberta, where restructuring started in the mid-1990s, unbundling vertically integrated utilities, opening up transmission access and creating a competitive wholesale electricity market. Today Alberta’s transmission facilities have become the properties of separate companies or continue to be owned by the utilities and operated by an independent system operator (ISO). Transmission facilities continue to be regulated by a commission or board in most jurisdictions.

Because of industry restructuring, “open access” has emerged as a way to ensure that owners of transmission lines allow non-discriminatory access to their lines. This is essential to enabling buyers to purchase electricity from the most competitive generation sources. Alberta, Ontario, British Columbia, Saskatchewan, Manitoba and Quebec all offer open access to transmission.

Electricity trade

Canada, the world’s second largest exporter of electricity, is an active participant in North American electricity trade. Most provinces are connected with their nearest U.S. neighbours. This cross-border trade allows generators to operate more efficiently, as they can continue to generate electricity, even when local demand is low. With open markets and shared transmission lines, power can be sold across hundreds of kilometres.

Canada typically exports between six and 10 per cent of its production to the United States. In 2002, Canada exported 36 terawatt-hours of electricity (worth $1.8 billion) to the United States. Exports are sold primarily to the New England states, New York State, the Midwest, and the Pacific Northwest and California.

Hydropower systems, which can store water during off-peak systems and then release the water for power production during peak periods, are well suited for the export of electricity. As a result, provinces with large hydro systems, such as Quebec, Manitoba and British Columbia, have been the largest exporters of electricity to the United States.

In 2002, Canada imported about 17 terawatt-hours of electricity from U.S. suppliers.

North American transmission grid

In the United States, the Federal Energy Regulatory Commission (FERC) has mandated that regional transmission organizations (RTOs) oversee the administration of transmission systems in competitive electricity markets. Given the international nature of the transmission grid, FERC has encouraged Canadian participation and, in some cases, has directed the RTOs to indicate how Canadian transmission entities would be represented.

All provinces are interconnected with neighboring provinces, allowing them to import and export power. East-west transmission is less common than north-south transmission. To date, most of the inter-provincial exchange of power has occurred in Eastern Canada, with the largest transfers between Quebec and Labrador. Canadian utilities and government leaders are currently exploring ways to increase east-west electricity flow, especially between Ontario and Manitoba and Ontario and Quebec, for better flow of electricity between provinces. The territories are neither interconnected, nor do they have connections with the provinces or the United States.

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