Nova Scotia Power's parent company says the Muskrat Falls hydroelectric project would add a $1.50 per month to the average household's power bill over the first five years.
Emera Inc., the province's private utility, said power rates would then remain stable or decline over the next 30 years.
The company says the calculation considers the costs of the Maritime Link subsea cable portion of the project and projected savings because of a reduced reliance on coal-fired electrical generation.
Emera is expected to file an application for the project's approval before the Nova Scotia Utility and Review Board on Monday.
It says the application is not a request to recover project costs through power rates.
Emera said that will happen through a separate application process once the Maritime Link nears completion in 2017.
The 180-kilometre cable could see as much as 40 per cent of the electricity from the 824-megawatt project in Newfoundland and Labrador moved to Cape Breton. It's the largest investment Emera Inc. has ever made.
Muskrat Falls is expected to produce power by late 2017.