More than 3 gigawatts of data center power abruptly disconnected from the PJM Interconnection grid in northern Virginia on July 22, causing a voltage disturbance that rippled across the eastern United States to Chicago, according to Reuters and grid operator PJM. The northern Virginia data center disconnect represented about 3% of the grid’s total electric demand at the time and took approximately 10 minutes to fully stabilize, exposing the growing vulnerability of the nation’s largest electric grid to sudden load swings from AI-powered facilities.
When a transmission line went out of service Wednesday morning, the data centers’ own control systems automatically unplugged from the grid and transferred to backup power, Dominion Energy 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,” the utility said.
Bob Marshall, CEO of Ting Labs, whose network of 1.4 million sensors recorded the disturbance, called it “a massive event.” He noted that customers in northern Virginia reported flickering lights and noises from air conditioners and refrigerators. “The power quality took a pretty big hit,” Marshall told Reuters. Grid disturbances are normally corrected in milliseconds, but this one required about 10 minutes.
PJM reported the sudden drop in power demand and a change in the grid’s frequency, which measures the balance of electricity supply and demand. The grid operator said there were no impacts to PJM’s overall reliability from the event, though it underscores why federal and state regulators are studying measures to better manage sudden demand drops from data centers and crypto miners.
The incident highlights a larger crisis building across PJM’s 13-state territory, which serves 67 million people. Data centers are connecting to the grid faster than new power supply can be built. According to the Natural Resources Defense Council, PJM forecasts adding 5 to 7 gigawatts of data center demand annually but only 2 to 3 gigawatts of new power supply through 2032.
Starting in summer 2026, PJM will have just enough power to keep the grid reliable, according to NRDC analysis. If nothing changes, the region may fall below reliability standards by June 2027, creating a greater risk of rolling blackouts during winter storms and summer heat waves. Tom Rutigliano, senior advocate at NRDC, warns that PJM consumers will pay an extra $163 billion through 2033 as new data centers continue to exceed available power supply. By 2028, an average family in the region could pay around $70 per month extra on electricity bills.
A comparable precedent occurred on July 10, 2024, when 1,500 megawatts of data center load in northern Virginia disconnected without warning, nearly causing a blackout. That event prompted federal and state regulators to begin studying how to prevent similar incidents as data center demand surges due to artificial intelligence development.
NRDC and a bipartisan coalition of over 50 state legislators have proposed that data centers be required to bring their own power capacity—through new generation, battery storage, or demand response programs—rather than relying on the public grid. This approach, they argue, would protect ratepayers and clarify responsibility for grid reliability during tight supply periods. Data center power demand has already driven capacity prices in PJM to historic levels, contributing to a $9.4 billion charge to consumers this summer alone.
Sources
- Reuters — reported the 3 GW disconnect, transmission line trigger, voltage disturbance extent, stabilization timeline, and Dominion Energy statement
- PJM Interconnection — confirmed the 3 GW load drop, frequency change, and no reliability impact
- Ting Labs — Bob Marshall’s sensor network data on disturbance extent and stabilization time
- Natural Resources Defense Council (NRDC) — PJM forecast data, reliability timeline, cost projections, and policy recommendations
- DataCenter Knowledge — corroborated the event and July 2024 precedent
- Utility Dive — expert analysis on data center impacts and grid reliability risks
