Massive disconnect of power roils largest US electric grid

By Tim McLaughlin Thu, July 23, 2026 at 1:02 AM UTC

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By Tim McLaughlin

July 22 (Reuters) - A massive amount of data center power abruptly disconnected from the largest U.S. electric grid on Wednesday, causing a voltage disturbance that could be felt from Washington, D.C., to Chicago, according to experts and data from grid operator PJM.

The epicenter of the event was in northern Virginia, home to the largest collection of data centers in the world. When an area transmission line went out of service Wednesday morning, the data centers' own control systems unplugged from the electric grid and transferred to backup power, Dominion Energy, the electric utility for the region, said in a statement.

"Within minutes of the incident occurring, our system operations team was able to stabilize the situation and return to normal operating conditions," Dominion said.

The Virginia event underscores why federal and state regulators are studying measures to better manage sudden drops in demand from data centers and crypto miners that can destabilize grids.

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Bob Marshall, CEO of Ting Labs, said his company's network of 1.4 million sensors recorded a range of voltage disturbances that extended along the eastern United States and to Chicago in the Midwest.

Grid disturbances are routinely corrected by operators and utilities in a matter of milliseconds, Marshall said. But Wednesday's event took about 10 minutes before the grid was fully stabilized, he said.

"This was a massive event," Marshall said. "Our customers in northern Virginia reported flickering lights and noises coming from their air conditioners and refrigerators. The power quality took a pretty big hit."

PJM Interconnection, the grid operator for 67 million people in a territory that stretches from Washington to Chicago, reported more than 3 gigawatts of power demand going offline, or about 3% of the grid's total electric demand at the time, according to PJM operations data.

PJM said it registered the sudden drop in power demand and a change in the grid's frequency, which measures the grid's balance of electricity supply and demand. But there were no impacts to PJM's reliability.

(Reporting By Tim McLaughlin; Editing by Nia Williams and Kim Coghill)

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