A power line failure near Washington, D.C.

, caused more than 3 gigawatts of data center load to disconnect from the PJM grid in about 30 seconds, triggering a voltage spike that flickered lights across the region.

The event was roughly double the scale of a similar 2024 incident on the same grid.

The root cause is that many data centers, sensing a voltage dip, all switched to backup power nearly simultaneously, removing their load from the grid and creating a supply-demand imbalance.

PJM operates the largest U.S. grid, covering 67 million customers from New Jersey to Illinois.

The disconnected load represented about 3% of total demand, but grid stability requires near-perfect balance.

Ali Zain Banatwala of the Independent Electricity System Operator told TechCrunch that co-located large loads need to coordinate sequential disconnection or reconnection.

An alternative approach is to build data centers that absorb grid disruptions instead of disconnecting. Startup ON.

Energy is deploying an uninterruptible power supply for entire data center campuses — covering servers, chillers, and other equipment — using a bank of batteries and power conversion equipment that presents a consistent load to the grid.

The system can charge batteries from surplus power and dispatch power during dips, responding in milliseconds. ON.Energy is currently installing 3 gigawatts of its systems at four campuses.

Grid operators are starting to act: ERCOT will require large loads like data centers to “ride through” disruptions.

By 2040, data centers are expected to account for 24% of PJM’s load, up from about 6% in 2024.