Officials say the outages are the result of an equipment failure at an electrical substation in Maryland. Power was out at several federal buildings including the White House, the U.S. Capitol Building, and the State Department, and the outages also impacted a number of Metro stations—leaving workers and tourists in D.C. concerned about how and why something like this could happen.
Pepco spokesman Sean Kelly spoke with FOX 5's Bob Barnard live on FOX 5 News Morning on Wednesday to explain more about just what happened. Kelly says the failure happened at a Pepco substation in Charles County, where a broken insulator led to a transmission line coming down.
According to Kelly, the failure caused a flash, but more significant to the downtown DC area was a dip in voltage that occurred. When that happened, Kelly says a number of buildings in town—especially the commercial or federal buildings—that have a backup system were switched over to the backup system when the primary systems sensed a dip in voltage.
Kelly says in many cases, the lights went out and then came right back on when the power switched over to the backup system. In other cases, the backup system didn't necessarily provide light. Still, Kelly says there was never a complete loss of power going to those buildings.
In some cases, Kelly says, it took some time to get the power back up and running once that initial switch had been made.
When the scattered outages occurred, Homeland Security officials said there had been an "explosion." Kelly said Pepco instead refers to it as a flash, rather than an explosion.
Tuesday's outages will be something Pepco reviews, looking at the protective schemes that are in place for the grid. Kelly said they will be reviewing the systems to make sure that if there is a dip in voltage or another problem with the system in the future, the grid will be able to isolate and protect itself.
"We're in the process of trying to learn what worked in the design, what didn't work—and there will be lessons learned," Kelly said.
Kelly said Pepco is working year-round to upgrade their system, constantly looking at the system to make sure that the designs that are put in place will work and that the backups will work. He said it's important to note that Tuesday's problem was just a dip in voltage, and that there was never a loss in power.