One downed line dropped 3.1 GW of data centres off the grid in 30 seconds

A 25 July 2026 account of a fault near Washington, DC describes roughly 3.1 gigawatts of data centres switching to backup power almost simultaneously within 30 seconds, leaving a 3.49 GW surplus that pushed voltage spikes across the PJM grid from Northern Virginia to Chicago and took 11 minutes to settle — double the size of a comparable 2024 event at 1.5 GW. Data centres were 6% of PJM load in 2024 and are projected at 24% by 2040. ON.Energy is installing campus-scale battery systems across four sites totalling 3 GW so facilities ride through a disturbance in milliseconds instead of disconnecting, and ERCOT already requires large loads to support ride-through.

What it means Compute siting is now a grid-engineering problem: whether a campus can ride through a fault is becoming as load-bearing to the build programme as square footage, water or cooling.