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Our Subsidiaries


Hydro One Networks Inc. 

Hydro One Networks, our largest subsidiary, is involved in the planning, construction, operation, and maintenance of our transmission and distribution network.

Our transmission system carries electricity from generating stations to local distribution companies and large industrial customers through our high-voltage network of transformer stations, transmission towers and wires.

We own 97% of transmission in Ontario with almost 30,000 km of high-voltage transmission lines. We also own and operate 26 interconnections with neighbouring provinces and states, which allow electricity to flow into and out of Ontario.

Our distribution system delivers electricity at lower voltages to homes, farms and businesses through our network of hydro poles and power lines. Our network is the largest in the province, with 121,000 km of wires serving 1.4 million customers, mostly in rural areas.

Hydro One Telecom Inc. ​

Is involved in marketing our excess fibre-optic capacity. www.HydroOneTelecom.com

Hydro One Remote Communities Inc. 

Operates and maintains the generation and distribution assets used to supply electricity to 19 communities across northern Ontario that are not connected to the province's electricity grid. Learn more. 

​Great Lakes Power Transmission LP 

On October, 31, 2016, Hydro One Limited announced the closing of the purchase of Great Lakes Power Transmission LP ("Great Lakes Transmission"). The sale was approved by the Ontario Energy Board (OEB) on October, 13, 2016. The Great Lakes Transmission business consists of 15 transmission stations, 560 kilometers of high and medium voltage 44-230 kV transmission lines, and related infrastructure covering an area of 12,000 square kilometers and connects to Hydro One's Wawa and Mississagi transmission stations. Great Lakes Transmission will begin to operate under the name Hydro One Sault Ste. Marie in early 2017 and will continue to operate as a standalone licensed transmitter.  

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