The Board of Commissioners of Public Utilities says an interim report by mid-May will review how the system failed and recommend changes needed for coming winters.
The board will then assess the system up to and after power flows from the $7.7-billion Muskrat Falls hydro project in Labrador.
Critics have questioned whether Crown corporation Nalcor Energy has a sufficient backup plan in case Muskrat Falls power fails.
But Newfoundland and Labrador Hydro, a Nalcor company, told the board in a pre-hearing that its inquiry should be short-term.
Its view was at odds with the province's other major utility, Newfoundland Power, which called for a longer focus to guide planning.
A key question is whether the province should shut down its main oil-fired Holyrood (HO'-lee-rood) power plant once Muskrat Falls is online.
Rotating and unplanned blackouts last month affected up to 190,000 customers on the island.
They were blamed on a cold snap, high winds and equipment that failed or was down for maintenance.