Toronto households using more than 800 kilowatt-hours per month should brace for a jolt on their electricity bills this year.

The city-owned utility says residential customers will pay about $77 more in the current 12-month billing cycle after receiving approval from the Ontario Energy Board last year. The OEB regulates the province’s electricity and natural gas sectors and sets electricity rates.

“The impact on your bill in 2016 is higher due to the delayed approval of rates and the need to cover time-sensitive system investments . . . designed to maintain the system, replace aging infrastructure and help maintain reliability,” the utility said in a notice to customers.

Overall, between 2015 and 2019, Toronto Hydro monthly residential bills are set to rise by an average of $2.44 or 1.7 per cent, in order to help replace aging assets, improve reliability and help protect the electricity grid against extreme weather, the utility said. Rates are subject to change.

Toronto Hydro says its electricity grid is the oldest in Ontario and requires more investment than newer municipalities.

“Aging infrastructure is the leading cause of power outages in the city — with 40 per cent of outages related to aging or defective equipment,” said a utility backgrounder.

“The need for investment in Toronto Hydro’s infrastructure is necessary as approximately one-third of power equipment in the city will reach its end of life by 2020.”