One downed power line flickered lights from Virginia to Chicago. AI data centers caused it.
When a single transmission line failed near Washington, DC, more than 3 gigawatts of data center power vanished in seconds. The grid took 11 minutes to recover. It is a warning sign of what comes next as AI demand keeps growing.
Key points
- A power line failure near Washington, DC this week caused 3.49 gigawatts of surplus electricity to hit the PJM grid, the largest grid operator in the United States, serving 67 million customers.
- About 3.1 gigawatts of data center load disconnected within 30 seconds, causing voltage to spike from Northern Virginia all the way to Chicago.
- The mass disconnection was roughly twice the size of a similar event in 2024, when 60 data centers pulled 1.5 gigawatts from the grid simultaneously.
- Data centers currently make up about 6% of PJM's total electricity demand; analysts expect that share to reach 24% by 2040.
- One startup, ON.Energy, is already installing 3 gigawatts of battery-based stabilisation systems across four data center campuses.
A single power line fell near Washington, DC this week. Normally the grid bounces back in a few seconds. This time it took more than 11 minutes, and for a stretch of that time, lights flickered across a swath of the eastern United States stretching all the way to Chicago.
The culprit was a sudden, simultaneous decision made by dozens of data centers in Northern Virginia.
What actually happened?
When the power line failed, the voltage on the PJM grid, which manages electricity from New Jersey to Illinois, dipped briefly. Data centers are designed to protect their equipment from exactly that kind of wobble. So, within seconds, they switched to their own backup generators and disconnected from the public grid.
The problem is they all did it at once.
About 3.1 gigawatts of demand, roughly the output of three large nuclear reactors, vanished from the grid in around 30 seconds, according to PJM data. The grid, suddenly supplying far more power than anyone was drawing, spiked to 3.49 gigawatts of surplus. That surge sent voltages rippling across the region, which is what made bulbs flicker in homes and offices far from Northern Virginia.
First reported by TechCrunch, the event caused voltage spikes measured by Ting Labs, a startup that tracks grid health through sensors plugged into ordinary electrical sockets across the country.
Why does this keep happening?
The grid has to stay in near-perfect balance at all times. Supply and demand must match closely, or voltages swing. Small swings are fine. Large swings trigger automatic safety systems inside the grid and inside individual buildings, which then disconnect to protect themselves.
The snag is that Northern Virginia holds the highest concentration of data centers anywhere in the world. When one senses a voltage dip, they all do, and they all react within seconds of each other.
"We need to figure a way for these loads that are located next to each other to sequentially either disconnect or reconnect," Ali Zain Banatwala, a senior market models specialist at the Independent Electricity System Operator, told TechCrunch.
This week's event was about twice as large as a similar episode in 2024, when 60 data centers pulled 1.5 gigawatts from the grid at once.
| Event | Year | Load dropped | Recovery time |
|---|---|---|---|
| Northern Virginia cascade | 2024 | 1.5 GW | Not disclosed |
| Northern Virginia cascade | 2025 | 3.1 GW | 11+ minutes |
| Data centers' share of PJM load | 2024 | ~6% | , |
| Projected share of PJM load | 2040 | ~24% | , |
What is the fix?
One answer comes from a startup called ON.Energy. The company wraps an entire data center campus behind a large bank of batteries and smart power-conversion equipment. The grid sees one steady, well-behaved customer instead of a cluster of machines that can vanish in a heartbeat.
If grid power dips, the batteries fill the gap instantly, measured in milliseconds, so the data center never needs to disconnect. If there is surplus power, the batteries soak it up. ON.Energy is currently fitting its systems across four data center campuses, totalling 3 gigawatts of capacity, according to the company's chief technology officer, Ricardo de Azevedo.
Regulators are also moving. Texas's grid operator, ERCOT, plans to require large customers like data centers to "ride through" disruptions rather than disconnect.
"It's the canary in the coal mine," de Azevedo said.
The honest takeaway: if you are a business owner near a data center hub, or simply someone who noticed the flicker, the underlying issue is one of coordination, not catastrophe. But it will only get harder to ignore as AI training demands more power each year. Asking your local utility what it is doing to manage large industrial loads is a completely reasonable question, and right now.
