Toronto Hydro has submitted a five-year rate application it says it needed to invest in the city's aging electricity grid.

The plan calls for $4 billion in funding to replace aging assets, meet growing demand, improve reliability and safeguard against extreme weather events.

If approved, the plan would raise the total bill for residential customers by about $3.54 per month for the average household -- for each of the next five years.

For 2015, the plan calls for a rate increase of just over 2.5 per cent, or $3.10 per month for the average household.

The application is subject to approval by the Ontario Energy Board.