Transmitters are responsible for the operation of all the lines, switches and transformers located at remote control centres.

They are also responsible for the maintenance of the lines, switches and transformers. Their maintenance responsibilities include:

• routine inspections of lines and equipment
• testing and servicing equipment
• providing right-of-way maintenance
• performing repairs when required.

Hydro One transmits approximately 97 percent of the power in Ontario. Other transmission companies include Great Lakes Power, Canadian Niagara Power and Five Nations Energy Inc.

These companies use a high-voltage system to transmit electricity from generating facilities across the province to local distribution companies, municipal utilities and large industrial consumers.

Hydro One is a provincially owned corporation that operates the majority of Ontario's electricity transmission lines. It is responsible for almost all of Ontario's transmission capacity across high-voltage lines through its subsidiary Hydro One Networks. It is also responsible for the local distribution of electricity in some Ontario communities, including some remote communities. Click here to visit the Hydro One website.

The Ontario Energy Board is the regulator of Ontario's natural gas and electricity industries. The board regulates the transmission, distribution and generation companies. It also regulates both the Independent Electricity System Operator and the Ontario Power Authority.

The electricity transmission system is carefully regulated by the Ontario Energy Board. Some of the ways the board ensures efficiency and fairness in the system include:

• creating transmission system standards
• managing rate hearings
• evaluating appeals from stakeholders.

The Independent Electricity System Operator's role is to operate the transmission system reliably and to balance the demand for electricity with the supply. It is also responsible for the competitive wholesale market.

The Independent Electricity System Operator works on a rigid schedule in which operators maintain power flowing through the system every five minutes. It also forecasts consumption throughout the province and collects the best offers from generators to provide the required amount of electricity.

Customers are able to see how prices fluctuate based on supply and demand, and to shift their consumption away from peaks in demand to times when demand and price are lower.

The Ontario Power Authority's primary functions are to:

• recommend preferred transmission systems
• develop plans for a reliable and sustainable system
• ensure that Ontarians will have enough power in the future by proposing new generation facilities in strategic areas.