Nova Scotia Power customers may be shocked to see how much their residential rates could rise in 2020 after three years of much smaller increases being sought by the utility.

The power company announced Monday it is seeking approval from the province's Utility and Review Board for fuel cost adjustments that will see residential rates rise 1.4 per cent — or $2 per month on average — in 2017, 2018 and 2019.

Not mentioned in the statement, however, is what could happen when the three years of stability are over. In the 546-page application published to its website, the utility aims to increase rates for residential customers 6.4 per cent in 2020.

Most other customer classes could also be hit with considerable increases in 2020:

Commercial business

Small: five per cent (1.6 per cent each of the three years prior)

Medium: 8.5 per cent (0.6 per cent each of the three years prior)

Large: 1.1 per cent (3.8 per cent each of the three years prior)

Industrial business

Small: 8.3 per cent (0.9 per cent each of the three years prior)

Medium: 6.9 per cent (1.6 per cent each of the three years prior)

Large: 7.5 per cent (1.5 per cent each of the three years prior)

In its statement, the utility says it won't be filing for a general residential rate increase for the next three years. The rate includes non-fuel costs such as labour, equipment and supplies.

"Our investments in diverse electricity sources, prudent fuel procurement and strict corporate cost control allow us to offer great predictability and stability for our customers," CEO Bob Hanf said in Monday's statement.

Rates for residential customers went down 0.9 per cent on Jan. 1. When the utility announced those changes in December, it said fuel costs were likely to increase between 2017 and 2019.

Fuel costs cover coal, natural gas and renewable energy contracts used to generate electricity. The base cost of fuel can be reset every second year or during a general rate proceeding.

The Utility and Review Board will consider the utility's application during a hearing in June.