Grid 101

Grid 101

Your electricity comes from all sorts of traditional and renewable sources. Learn how it gets to you and our plan for keeping electricity affordable, sustainable and resilient in the bright years ahead.

Getting Power to You

What connects us all

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Toronto Hydro owns and operates an electricity distribution system that delivers electricity to more than 750,000 customers in Canada’s largest city.

It is the largest municipal electricity distribution company in Canada and distributes approximately 18% of the electricity consumed in the province of Ontario.

Generation to Transformer Station to Municipal Substation to Distribution Lines to Residential Homes and Businesses


Nearly half of Ontario’s electricity is generated by Ontario Power Generation, a provincially-owned organization with generating stations across the province that produce electricity from nuclear, hydro and thermal energy sources.


Once electricity is generated, it’s delivered to urban and rural areas through high voltage distribution lines that act like highways for electricity.


Toronto Hydro is responsible for the last step of the journey: distributing electricity to customers in Toronto.

By the numbers

As of 2014

By the numbers

Providing value to our city

Toronto Hydro's sole owner and shareholder is the City of Toronto. The Ontario Energy Board, an independent government agency that regulates our rates and services, allows Toronto Hydro to earn a set annual return on our distribution system investment. Part of these earnings pay an annual dividend to the City that could be used to help fund city services. The remaining portion is invested back into the utility, to fund maintenance and improvements.

Grid Sustainability

Improving, innovating, investing

Electricity infrastructure is the trusted backbone of Toronto’s economic and social life. What will our city’s infrastructure look like in 20 years? Our sustainable electricity future depends on new systems and new thinking. Modernizing the grid to make it smarter and more resilient is at the top of our priorities.

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Key opportunities
and challenges

Toronto’s high quality of life is driving dramatic population growth. As density rises, significant investment is needed if the city is to meet its dual goals of meeting growing demand and reducing greenhouse gas emissions. Keeping up with growing demand is a pressing challenge.

Toronto’s dramatic growth is new, but our electricity grid is not. Originally built largely in the 1950s and ’60s, more than a third of our infrastructure will reach the end of its useful life by 2020. In order to maintain reliability, it is necessary to invest now. That’s why we’re replacing hydro poles, transformers, cables and underground equipment as part of a long-term infrastructure renewal investment program.

Reasons for outages

Did you know?

Aging equipment is currently the leading cause of power outages in Toronto:

Assets from 2015 and 2019
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Our five-year investment plan: 2015–2019

Between 2006 and 2015, Toronto Hydro invested $2.9 billion to renew the distribution grid. A further $2 billion in capital funding was approved by the Ontario Energy Board to improve reliability and generate growth – this is being rolled out from 2015 to 2019.

In tandem with our system revitalization work, we’re developing smart grid technology to help reduce outage restoration times and increase the responsiveness of the distribution system, to help improve reliability and enhance the overall customer service experience. This is a long-term investment for a smarter, better grid.

Learn more about our innovative power projects

What does this mean for the city?

Investing in the grid is an investment in the city, not only powering growth and improving reliability, but also stimulating economic development and helping create jobs.

This work is already paying off

The duration and frequency of outages due to defective equipment is declining.

Frequency of outages to defective equipment (system wide)*
Frequency of outages to defective equipment (system wide)

Since 2009, Toronto Hydro has invested over $2.5 billion in the grid. In that time, the average number of service interruptions has improved by 12% and the average duration of interruptions has improved by 23%. But there’s still more to do.
* Excludes major event days.

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Keeping electricity affordable

The Ontario Energy Board (OEB) is responsible for setting electricity rates for all Ontario utilities. Typically, the OEB reviews electricity prices for households and businesses twice each year, on May 1 and November 1.

See current rates

What can I do to further manage my electricity costs?

We’re here to support you in managing your energy use and costs. Under Ontario’s Conservation First Framework, Toronto Hydro and all other provincial utility companies are pursuing ambitious energy reduction targets and building a culture of conservation. For every $1 invested in energy efficiency, Ontario has avoided about $2 in costs to the electricity system.

We offer residential customers discounts on a wide range of energy-efficient products such as LED light bulbs and ceiling fans, rebates for high-efficiency heating and cooling systems, and much more.

Business customers may also qualify for rebates for energy audits, equipment retrofits and other energy-efficiency measures.

Grid Resiliency

Climate change and the electricity grid

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Adapting to climate change

Strengthening our electricity system

In 2015, Toronto Hydro assessed the vulnerability of Toronto’s aging electric infrastructure to extreme weather events and future climate change. The study found that while the GTA’s transmission system is generally resilient, measures to enhance resiliency, especially for aging infrastructure, can help avoid or minimize the impact of severe weather.

The study followed the Public Infrastructure Engineering Vulnerability Committee protocol developed by Engineers Canada.

Preparing for higher temperatures and more severe storms

Over the next 30 years, Toronto is expected to see more extreme weather events, including higher summer temperatures and more intense rainfall. We’re working to renew and replace our infrastructure to help decrease the number of disruptions caused by severe weather. In addition to making power poles, lines and other hardware more robust, we’re improving grid resiliency with clean energy projects and other supporting measures such as demand reduction and energy conservation programs, and by enhancing our emergency response and service restoration processes.

Toronto’s future weather

Toronto's Future Weather


Extreme heat

With more consecutive days of higher heat and humidity, demand for air conditioning is expected to increase, placing greater stress on the overall electrical system and causing equipment malfunction. Increasing transmission station capacity helps us prevent outages caused by extreme heat.

Heavy rainfall

Severe thunderstorms and heavy rainfall can cause system-wide vulnerabilities. Heavy rain can flood underground feeder cables, causing electrical failures. Investing in submersible and moisture-resistant underground cables helps us limit the number of power failures resulting from flooding.

Ice storms

Freezing rain, ice storms and high winds damage overhead equipment due to ice weight, falling trees, branches and debris. Installing tree-proof conductors, moving critical sections of circuits underground and relocating vulnerable circuits helps us improve system performance in a severe weather event.

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Safety and outages

Get the latest power outage information on our outage map, follow us on Twitter @TorontoHydro or check local media outlets for updates.

For electrical emergencies (such as downed lines) and to report an outage in your neighbourhood, call our 24-hour hotline at 416-542-8000 and press option 1 to reach our emergency dispatch department. If you are unable to reach Toronto Hydro call 911 for police or fire.

Prep your 72-hour emergency kit now

Get updates during major outages and emergencies

Our new mobile-friendly Outage Centre makes it easy to keep the latest news and live updates at your fingertips. To add the Outage Centre to your smart phone or tablet’s home screen, go to and select “Add to home screen.”