Massive disconnect of power roiled largest US electric grid

• The sudden disconnect represented about 3% of PJM's total electric demand at the time, with the epicenter in northern Virginia, home to the world's largest collection of data centers
• Customers reported flickering lights and noises from appliances, with voltage disturbances detected across 1.4 million sensors stretching from the eastern U.S. to Chicago
• The incident highlights concerns about sudden demand drops from data centers and crypto miners, prompting federal and state regulators to study grid stabilization measures

Summary: Major Power Disturbance Hits PJM Grid

Key Event Details:

On Wednesday, July 22, a significant power disturbance struck PJM Interconnection's territory at approximately 7:55 a.m. ET, with more than 3 gigawatts of power demand suddenly disconnecting—representing roughly 3% of the grid's total electric demand at the time. The disturbance took approximately 10 minutes to fully stabilize, unusually long compared to typical millisecond corrections.

Geographic Scope:

The event affected PJM's service area spanning from Washington, D.C., to Chicago, impacting 67 million people. The epicenter occurred in northern Virginia, home to the world's largest concentration of data centers. Voltage disturbances were recorded across the eastern United States and into the Midwest.

Impact and Implications:

While PJM reported no impacts to grid reliability, customers in northern Virginia experienced flickering lights and appliance noises, indicating compromised power quality. Bob Marshall, CEO of Ting Labs, whose 1.4 million sensor network detected the event, characterized it as "massive."

Regulatory Context:

The cause remains unknown, but the incident highlights growing concerns among federal and state regulators about managing sudden demand drops from data centers and cryptocurrency mining operations, which can destabilize electrical grids.

Companies Mentioned:

• PJM Interconnection (grid operator)
• Ting Labs (monitoring company)
• Dominion Energy (electric utility, no comment provided)

This event underscores emerging challenges as power-intensive technology operations increasingly strain grid infrastructure, prompting regulatory scrutiny of data center and crypto mining impacts on electrical system stability.