What exactly happened when the power line went down?

When the power line failed, data centers in Northern Virginia sensed the voltage dip and switched to backup power within about 30 seconds, removing about 3.1 gigawatts of load from the grid. This sudden removal of demand caused the grid's voltage to spike, creating an imbalance that took another 11 minutes to stabilize and caused lights to flicker across the region from Northern Virginia to Chicago.

Why is 3 gigawatts a big deal if it's only 3% of the grid?

The electrical grid must operate in near-perfect balance between supply and demand. When data centers all disconnect at nearly the same time, the sudden loss of demand causes the grid's supply to surge, triggering voltage spikes that can damage equipment or force safety disconnections across the region. The problem will worsen as data centers are expected to grow from 3% to 24% of PJM's load by 2040.

What solutions are being developed?

ON.Energy has created an uninterruptible power supply that covers entire data center campuses, hiding them behind batteries and power conversion equipment so the grid sees a consistent load rather than peaks and valleys. The system allows data centers to absorb power fluctuations instead of disconnecting. ON.Energy is currently installing 3 gigawatts of such systems across four data center campuses, and grid operators like ERCOT are beginning to require large loads to "ride through" disruptions.

AI Business & IndustryTechCrunch AIJul 25, 2026Jul 26, 2026, 01:01 JST

Power line failure exposes AI data center grid crisis

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3 Key Points

What happened
A downed power line outside Washington, DC this week caused more than 3 gigawatts of data centers to disconnect nearly simultaneously, triggering a voltage spike across the PJM grid from Northern Virginia to Chicago that lasted over 10 minutes and caused lights to flicker across the region, though no blackout occurred.
Why it matters
Data centers now represent around 3% of total demand on PJM's grid, and that share is expected to grow to 24% by 2040. When data centers sense power disruptions, they all switch to backup power within seconds of each other, creating a cascading effect that destabilizes the grid—a problem grid managers and startups are only now beginning to address as these mass disconnections grow more frequent.
What to watch
ON.Energy is installing 3 gigawatts worth of systems that let data centers absorb grid fluctuations rather than disconnect, and ERCOT is beginning to require large loads to "ride through" disruptions. The mass disconnection this week was twice as large as a similar 2024 event when 60 data centers pulled 1.5 gigawatts of load from the grid.

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Context & Analysis

Northern Virginia hosts the world's highest concentration of data centers, and the region sits within PJM's territory—the largest grid operator in the United States, serving 67 million customers across six states. The power line failure this week exposed a critical vulnerability: when data centers sense even a small voltage dip, they all make the decision to switch to backup power within seconds of each other. This synchronized response, intended to protect individual facilities, creates a cascade effect that destabilizes the broader grid. The problem is not new—a similar event occurred on PJM's grid two years ago—but the scale is worsening rapidly. In 2024, when 60 data centers disconnected simultaneously, they removed 1.5 gigawatts from the grid. This week's event was twice as large. Data centers already account for about 6% of PJM's load (or 3% at the time of the incident), and projections suggest they will grow to 24% by 2040, making today's grid management approaches unsustainable without intervention.

FAQ

What exactly happened when the power line went down?: When the power line failed, data centers in Northern Virginia sensed the voltage dip and switched to backup power within about 30 seconds, removing about 3.1 gigawatts of load from the grid. This sudden removal of demand caused the grid's voltage to spike, creating an imbalance that took another 11 minutes to stabilize and caused lights to flicker across the region from Northern Virginia to Chicago.
Why is 3 gigawatts a big deal if it's only 3% of the grid?: The electrical grid must operate in near-perfect balance between supply and demand. When data centers all disconnect at nearly the same time, the sudden loss of demand causes the grid's supply to surge, triggering voltage spikes that can damage equipment or force safety disconnections across the region. The problem will worsen as data centers are expected to grow from 3% to 24% of PJM's load by 2040.
What solutions are being developed?: ON.Energy has created an uninterruptible power supply that covers entire data center campuses, hiding them behind batteries and power conversion equipment so the grid sees a consistent load rather than peaks and valleys. The system allows data centers to absorb power fluctuations instead of disconnecting. ON.Energy is currently installing 3 gigawatts of such systems across four data center campuses, and grid operators like ERCOT are beginning to require large loads to "ride through" disruptions.

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