US Electric Grid Narrowly Dodged Huge Collapse During Storm (1)

The unprecedented strain on the electrical grid during December’s frigid storm was threatening to trigger cascading blackouts across the Eastern US when Duke Energy Corp. called for rolling outages in North Carolina to stabilize the system, company officials said Tuesday.

Duke cut power to about 500,000 homes and businesses the day before Christmas as frigid weather sent demand surging as much as 10% above forecast while instruments froze at coal and natural gas-fired plants, forcing them to cut output.

The strain in North Carolina threatened to throw the flow of power off balance on the entire Eastern Interconnection grid, stretching ...