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Single downed power line in Northern Virginia triggered a 3-gigawatt US grid disturbance stretching to Chicago

· by Pondero Newsdesk

The short version

On July 22, 2026, data centers in Northern Virginia switched to backup power within seconds of a transmission line failure, stripping more than 3 gigawatts from the PJM grid and sending voltage disturbances from DC to Chicago for 11 minutes.

Single downed power line in Northern Virginia triggered a 3-gigawatt US grid disturbance stretching to Chicago

On July 22, 2026, a transmission line failure near Washington, DC produced something grid engineers had not seen at this scale: data centers across Northern Virginia all switching to backup power within seconds of each other, pulling more than 3 gigawatts from the PJM grid simultaneously and sending voltage fluctuations across a roughly 1,000-mile corridor to Chicago, per TechCrunch's technical analysis published July 25.

What happened

When the area transmission line went out of service, data center control systems in Northern Virginia detected the resulting voltage dip and switched to backup power as designed. The problem was the density. About 3.1 gigawatts of load vanished from the PJM grid in roughly 30 seconds, pushing PJM's surplus to a peak of 3.49 gigawatts, per PJM operations data reviewed by TechCrunch. A normal fault recovery takes milliseconds. This one took 11 minutes before the grid fully stabilized, according to Bob Marshall, CEO of Ting Labs, whose network of 1.4 million residential IoT sensors recorded the disturbance range, per US News / Reuters.

Customers in northern Virginia reported flickering lights and audible strain on appliances. Dominion Energy, the region's utility, said its operations team stabilized conditions within minutes. The disconnected load represented about 3% of total PJM demand at the time. That fraction was large enough to cause visible effects across PJM's territory, which serves 67 million people from New Jersey to Illinois.

Why it matters

The July 22 event was twice the size of a comparable incident in 2024, when 60 data centers simultaneously disconnected and pulled 1.5 gigawatts from PJM, per Synapse Energy Economics data cited by TechCrunch. Data centers accounted for roughly 6% of PJM load in 2024 and are projected to reach 24% by 2040. The direction is clear, and the implications for anyone running AI workloads on that grid are concrete: the backup-power logic protecting individual servers is, at Northern Virginia's density, capable of amplifying a minor fault into a multi-state reliability event.

Ricardo de Azevedo, CTO at ON.Energy, called the incident "the canary in the coal mine" in comments to TechCrunch. Ali Zain Banatwala, a senior market models specialist at the Independent Electricity System Operator, identified the core fix: co-located large loads need a way to disconnect or reconnect sequentially rather than in a simultaneous burst, so grid operators can plan around the load shedding rather than absorbing it as an instantaneous shock.

Context and what to watch

ERCOT already requires large loads to "ride through" grid disruptions rather than disconnect. PJM has not matched that standard yet. ON.Energy is currently installing whole-campus uninterruptible power systems at four data center campuses totaling 3 gigawatts of capacity, a design that presents the grid with a single stable load instead of thousands of independent switching decisions, per TechCrunch.

Watch for a response from FERC or DOE. PJM's post-event reliability review and NERC's annual reliability assessment are the two most likely venues for mandatory data center disconnection sequencing standards to surface. The July 22 event provides the documented technical case that the 2024 incident, at half the size, did not clearly establish.

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