An aging substation caused Montreal’s latest blackout. Its replacement is still years away

The equipment failure that left thousands of Montrealers without power during this weekend’s bitter cold originated at a substation that Hydro-Québec has been aiming to replace since at least 2018.

Project documents show the utility has long identified the Hampstead substation as a weak link in the local grid.

Pascal Poinlane, a Hydro-Québec spokesperson, said the outage was caused by the failure of a breaker at the substation — an issue that is “not as easy to fix as a problem caused by a snowstorm.”

“When it happens in a substation with equipment like that, it takes more time,” he told CBC. He said generators were installed to restore power as quickly as possible.

François Bouffard, an associate professor of engineering at McGill University who closely follows the public utility, said that replacing a failed breaker is a complex task even under ideal conditions. 

“This is the kind of repair that can take several weeks to complete — in the summertime,” he said.

Without knowing the details of the malfunction, Bouffard said aging pieces of equipment are “bound to fail eventually” after being in use for more than half a century.

At the outage’s peak, more than 20,000 customers were without electricity on Saturday in Montreal and Côte Saint-Luc. Service was expected to be restored to all residents and businesses by the end of the day Monday.

Early Tuesday, some residents in Côte Saint-Luc and in Montreal's Notre-Dame-de-Grâce neighbourhood were still without power.

The City of Montreal said Monday that more than 50 people had used a warming centre in Côte-des-Neiges, some of them staying overnight.

While Hydro-Québec has a plan to completely rebuild the aging station, the project has faced delays and is not scheduled for completion until 2029. Further upgrades to the power lines servicing Côte Saint-Luc won’t be finished until 2031.

The plan calls for converting the facility from 120 kilovolts to 315 kilovolts to meet growing demand. The substation will also be renamed the Côte Saint-Luc substation to reflect its actual location, which is Côte Saint-Luc — not Hampstead.

A 2019 public notice stated that the rebuild was necessary to replace “aging equipment” and ensure the reliability of the power grid.

The substation has been in service since 1955. At the time, Hydro-Québec documents describe the site as being almost in the “middle of a field.” While the area was bordered to the southeast by a Canadian Pacific railway line, the surroundings were largely agricultural.