Summary (tl;dr)

Northern Virginia's "Data Center Alley" experienced a significant power disconnect on July 22, 2026, when a transmission line fault in Ashburn caused over 3 gigawatts of data center load to automatically switch to backup power, creating a widespread voltage disturbance across the PJM grid.

Essential Background

Northern Virginia is home to the world's largest concentration of data centers, often referred to as "Data Center Alley," which is crucial for global internet traffic and the rapidly expanding artificial intelligence (AI) infrastructure. This immense concentration of digital infrastructure places significant and growing demands on the electric grid. The North American Electric Reliability Corporation (NERC) has been examining how this rapidly growing data center load should be integrated into power system planning, especially after a smaller, but similar, incident in 2024 where roughly 1.5 gigawatts of data center load disconnected during a disturbance.

The Full Story

On Wednesday, July 22, 2026, a transmission line in Ashburn, Virginia, experienced a fault and automatically went out of service. This incident in "Data Center Alley" prompted hyperscale facilities to automatically transfer to their backup power systems, leading to more than 3 gigawatts of demand, approximately 3% of the PJM grid's total electric demand at the time, disappearing from the grid in seconds. Dominion Energy, the local utility, stated that the data centers' own protection systems initiated this transfer, not a utility-imposed load shed. While the event caused no reported reliability impacts to the bulk power system, it produced a measurable frequency change and a voltage disturbance that was felt as far away as Washington, D.C., and Chicago, with customers in Northern Virginia reporting flickering lights and noises from appliances. Grid operators typically correct such disturbances in milliseconds, but this event took about 10 minutes to stabilize the grid.

Why It Matters

This event highlights growing concerns about the stability and reliability of the electric grid due to the unprecedented velocity and geographic concentration of new demand from AI data centers. The incident underscores the challenge for grid operators, such as PJM Interconnection, in managing sudden and massive load changes, which can destabilize grids. Regulators and utilities are actively studying measures to better manage these situations, with NERC calling for improved modeling, monitoring, and communication with large loads. The rapid growth of data centers also raises broader concerns regarding their impact on communities, the environment, and the potential for increased electricity costs for households and small businesses, prompting calls for greater state-level oversight and transparency.

Geographic Location

• Ashburn, Loudoun County, Virginia, United States (transmission line fault and data center disconnect)
• Washington, D.C., District of Columbia, United States (voltage disturbance felt)
• Chicago, Cook County, Illinois, United States (voltage disturbance felt)