Why more Nova Scotians lose power in a storm than you realize

During severe weather, many Nova Scotians click on Nova Scotia Power's outage map to find out how many customers have lost electricity and where.

But the map doesn't tell the whole story.

The actual number of customers without electricity during a recent storm was higher than indicated by the outage map, according to information provided to the Nova Scotia Utility and Review Board.

And that's a normal occurrence, says Paul Casey, Nova Scotia Power's vice-president of transmission, distribution and delivery service.

The Utility and Review Board asked the power company for detailed information on the interruptions and restoration times associated with a big windstorm on Dec. 10, 2019.

At the time, the company said a maximum of 52,000 customers were without power at the same time during the storm. That's what appeared on the outage map.

Casey said about 78,000 households lost power at least once during the storm, while the number of instances of households losing power was about 116,000.

He said the peak outage number doesn't include households experiencing a second or subsequent outage, or households temporarily taken off the grid by Nova Scotia Power when the company is carrying out restoration work.

It's unclear what the peak number would be if those instances were included in Nova Scotia Power's figures.

"That would total a larger number [than 52,000]," said Casey.

Highest sustained winds on record

In its submission to the board, Nova Scotia Power released a graph tracking cumulative hours of winds above 80 km/h between 2005 and 2019 at stations in Yarmouth, Greenwood, Halifax, Truro and Sydney. The December windstorm capped a year that saw the most hours of sustained high winds on record.

These winds weaken trees and equipment, increasing the probability of outages.

Nova Scotia Power spends $100 million a year to maintain and upgrade transmission and distribution equipment, including $25 million for vegetation management.

The company said it's investigating battery storage and microgrids as it tries to harden its system as sustained high winds become more frequent.