Soaring temperatures on Tuesday pushed Alberta's demand for electricity beyond what it can deliver, so the power regulator ordered some utility companies to use less, which caused temporary rolling blackouts.
Epcor in Edmonton and the City of Lethbridge cut power to certain areas for up to an hour after the Alberta Electric System Operator ordered them to shed 100 megawatts of demand.
However, John Esaiw, director of market analytics and forecasting for Alberta Electric System Operator, said flood-affected areas, such as Calgary and High River, as well as hospital and emergency services did not have to reduce power load.
AESO said the record demand was due to a number of factors, including temperatures higher than 30 C across the province.
It also says other factors included a number of generators being offline for maintenance, a transformer unexpectedly went out of service and wind generation was low.
"It's just a matter of the hot weather and extreme temperatures, it has nothing to do with the wealth of the province or improper maintenance," Mr. Esaiw said.
The operator said it had to import electricity from B.C. and Saskatchewan to help meet demand.
About an hour after it issued the directive to reduce load, AESO lifted its order. It said power demand had dropped from a record high of 10,062 megawatts to 9,876 MW.
Epcor stopped its rolling blackouts shortly after.
The last time there were rolling blackouts was July 9, 2012.
But Mr. Esaiw said it was a completely different situation.
"We had eight of our power generation plants trip offline ... Today all our power generation has held up quite well today, it was a transmission issue that hit us today."