A large share of data center load abruptly disconnected from the PJM Interconnection grid on July 22, 2026, producing a voltage disturbance registered from Washington, DC to Chicago. The sequence began in northern Virginia, where a regional transmission line went out of service that morning. Data centers in the area disconnected from the grid and transferred to backup power, and the sudden loss of load moved voltage across the interconnection.
The event illustrates a control problem that grid operators have flagged as large loads concentrate geographically. Facilities protect their own equipment by islanding when they detect a disturbance, and when enough of them do so simultaneously the aggregate load step becomes a grid event in its own right.
PJM entered the summer with narrow margins. The operator forecast demand of 166,147 MW on July 2, above the all time record of 165,563 MW set in 2006. The Department of Energy issued two emergency orders authorizing PJM to curtail data centers and to waive power plant emissions limits through July 3.
Longer term projections describe a supply gap. Reports place the potential PJM shortfall at up to 60 GW over the coming decade, with data centers connecting faster than new generation can be built. Stakeholders approved a reliability backstop procurement plan on June 30, 2026 intended to secure supply against an expected shortfall within two years, and PJM has separately proposed distinct service categories for co-located data center load.
Source: Data Center Dynamics - https://www.datacenterdynamics.com/en/news/pjm-grid-hit-by-voltage-disturbance-after-data-center-load-abruptly-drops-offline-report/