Tens of thousands of Nova Scotia Power customers across the province lost power early Monday morning after freezing rain caused transmission issues.
About 56,000 customers in Halifax, Dartmouth, Antigonish County, Port Hawkesbury and Cape Breton Regional Municipality lost power around 5:30 a.m.
Matt Drover, a senior manager with the utility, said there was a significant amount of ice buildup on the high-voltage transmission line that connects Nova Scotia and New Brunswick. Freezing rain fell on the region throughout the weekend.
Drover said the ice buildup led to an outage on that line, which was causing the system to become unstable, with fluctuations in the grid.
Power cut to stabilize system
In order to stabilize the system, Drover said Nova Scotia Power needed to reduce overall electricity demand, so the utility shut off power to several areas, including parts of Halifax, Dartmouth, Truro, New Glasgow and Sydney.
Drover said when the utility needs to reduce customer load, it makes the decision on where to cut power based on the size of the circuit running from the substation to customers, targeting areas with lots of customers.
"So the bigger ones are the ones that we target and we do it in a geographical distribution as well. So not just in one pocket, we try to distribute it amongst the province.… The most customers makes it the easiest to do quickly."
Once the transmission line was reconnected, customers began to have their power restored, and all affected customers had their power restored by 8 a.m.
Other scattered outages remain, mostly in Cumberland and Colchester counties as well as Cape Breton. Most of those outages were caused by freezing rain, Drover said.
The majority of the remaining outages have an estimated restoration time of between late Monday morning and Monday afternoon.
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