A fallen power line near Washington, DC exposed how concentrated AI data centres can destabilise the electricity grid when they simultaneously switch to backup power. More than 3 gigawatts of demand disappeared within seconds, briefly creating an electricity surplus and causing voltage spikes and flickering lights across the PJM network; experts say similar incidents may become more common as data-centre capacity expands.

PJM, the largest US grid operator, serves 67 million customers from New Jersey to Illinois, including Northern Virginia’s exceptionally dense data-centre cluster. About 3.1 gigawatts of load dropped within 30 seconds, rising to a peak imbalance of 3.49 gigawatts—around 3% of demand—before the grid stabilised roughly 11 minutes later. Proposed solutions include staggering disconnections and reconnections, or using campus-wide battery-backed systems that allow data centres and cooling equipment to ride through short disturbances without leaving the grid.