Hydro One said thefts have increased from an average of 10 per month six months ago, to 16 per month during the summer.
Due to the problem of copper theft, Hydro One announced it is asking Canadians to call Crime Stoppers at 1-800-222-TIPS if they suspect copper theft.
It is also warning that copper thieves risk serious or fatal injury, especially if they try to steal the copper fittings that ground high-voltage equipment.
Hydro One was formed when the Ontario government split Ontario Hydro, forming Ontario Power Generation as the power plant company and Hydro One as the operator of both the high-voltage transmission network that distributes to industry and utilities, plus a low-voltage system that serves individual customers in rural areas and small communities.