While power outages are not uncommon in the U.S., widespread blackouts that last more than a couple of hours are pretty rare. However, this summer marks the 20th anniversary of one of the most significant blackouts in North American history. The incident didn’t just affect the U.S., but also major parts of Canada.

The blackout occurred on Aug. 14, 2003. The History Channel reports it began at 4:10 p.m. EDT, when 21 power plants shut down in just three minutes. Fifty million people were affected, including residents of New York City, Cleveland, and Detroit, as well as Toronto and Ottawa, Canada, among others. Although power companies were able to resume some service in as little as two hours, power remained off in other places for more than a day. The outage stopped trains and elevators, and disrupted everything from cellular telephone service to operations at hospitals and traffic at airports.

“It was close to quitting time in the afternoon, and given the warm weather in the middle of the summer and thunderstorm season, our system was holding up well. I was looking forward to actually leaving on time for a change,” Paul Toscarelli, senior director of Electric Transmission and Distribution (T&D) Operations for the Palisades Division with Public Service Electric and Gas (PSE&G), New Jersey’s largest utility, said as a guest on The POWER Podcast. Toscarelli was an engineer assigned to one of PSE&G’s regional distribution divisions at the time and was in the distribution dispatch office when the incident occurred. He recalled the event quite vividly.

“We were coming up around the second anniversary of 9/11, as I recollect, and just about everyone’s gut feel—instinctive feel—was this was another kind of terrorist attack,” Toscarelli said. “Looking back at it, it was very strange to recollect how relieved we were to find out it was just a widespread system outage of epic proportions.”

Of the 750,000 PSE&G customers that lost power that day, nearly three-quarters were back online within five hours and virtually all had service by noon the next day. PSE&G said diversification and design protections helped to contain the outage, and the company was safely able to reenergize the system circuit by circuit.

“The industry learned a lot about the electric system vulnerabilities,” said Toscarelli. Based on studies of the incident, the North American Electric Reliability Corporation (NERC) enhanced its standards in an effort to prevent future blackouts.

Since the 2003 blackout, PSE&G has spent billions of dollars to further enhance the reliability and resiliency of its T&D systems with the aim of mitigating future outages. In fact, the company’s planned capital expenditures this year are the largest in the utility’s history—more than $3.5 billion.

Among the projects PSE&G expects to complete in 2023 is a Newark Switch Rebuild Project. The Newark Switching Station is the heart of the company’s Newark T&D network. The $350 million project will modernize aging infrastructure that was put into service in 1957.

Another example is the $550 million Roseland-Pleasant Valley Project, which was completed in May and was one of PSE&G’s largest transmission projects to date. The 51-mile undertaking replaced transmission facilities that were, on average, about 90 years old.

“Infrastructure continually ages. It’s our job as the stewards of our system to monitor the usage of our equipment, inspect it, maintain it, and replace it where it’s deemed necessary, in a timely manner, and continuously repeat that process,” said Toscarelli. “We have an asset management model that involves risk assessment and risk scoring, and it lets us stay in the forefront of this.”