July 10, 2024. 7 PM. On a 230 kV transmission line somewhere in the Eastern United States, a single surge-arrester component failed. The protection system worked as designed and isolated the fault in under a second. In transmission operations this is utterly ordinary. It happens somewhere in the U.S. every day.
And yet, in the same region, at exactly the same moment, 1,500 MW of electrical load disappeared at once. That’s about one-and-a-half standard Korean nuclear units. Roughly twice the power consumption of all of Gangnam-gu in Seoul. The grid operator hadn’t cut anyone’s power. But someone had taken 1,500 MW away.
The investigation team chased the data. The vanished load was all data centers. The accident region was a data-center cluster, and those facilities had all disconnected themselves from the grid simultaneously, switching over to their own batteries and backup generators. The transmission operator had just witnessed, for the first time, the strange scene of load disappearing without anyone disconnecting it.
Data centers run on uninterruptible power supplies (UPS). A 0.01-second outage will kill a server, so the systems are designed to disconnect from the grid instantly the moment voltage wavers — even during a transient that brief. For a single facility, that’s a sensible piece of protection. But when dozens of facilities cluster in the same region, they all do the same thing at the same time. Like a choir performing the same piece.
When load disappears all at once, two things happen. The balance between generation and load breaks, frequency rises, and as the current in the transmission lines falls, voltage climbs. That day, frequency moved from 60 Hz to 60.047 Hz, and voltage climbed by up to 7%. Generators were on the verge of entering their own self-protection actions. Operators quickly disconnected reactive-power compensation devices to pull voltage back down. The incident calmed within a minute. They got lucky.
NERC, the North American Electric Reliability Corporation, traced the data and found that something similar was happening far more often in Texas. Twenty-six times in the two years and nine months between January 2023 and September 2025. Roughly once a month. Each event involved more than 100 MW of load vanishing in unison. This time the culprit wasn’t data centers — it was cryptocurrency mining facilities. In one of the events, 95% of the pre-event load dropped at once. After China banned domestic mining in 2021, miners migrated en masse to Texas; cheap electricity and abundant land pulled them in.
And then a new kind of problem appeared. AI training data centers. When training a large language model like ChatGPT, tens of thousands of GPUs repeat tightly synchronized computations. The facility’s total power consumption sloshes by more than 100 MW about once a second. A pattern peculiar to AI training, rarely seen in conventional cloud data centers. If that rhythm happens to align with the natural oscillation frequency of the transmission grid, like a child pumping their feet in sync with a swing, a single data center can rock a wide-area transmission grid. This has been observed in Texas and Virginia.
For a hundred years, power engineers have leaned on one assumption: “Generators are controlled, load is simply accommodated.” Plants carried strict obligations; load roamed free. A residential air-conditioner was never going to shake the grid.
In May 2026, NERC formally retired that assumption after a century. New guidance imposes plant-level obligations on data centers above a certain size: detailed facility modeling, real-time communications, the ability to ride through voltage disturbances, integrated cybersecurity. A declaration that load is no longer a passive guest, but must become an active participant. The recommendation is set to convert into a mandatory standard in the future.
Korea is heading toward a similar landscape. Data centers concentrate in the Seoul Capital Area, AI training scales up in earnest, and transmission infrastructure is hard-pressed to keep up. The cautious stance KEPCO (the Korea Electric Power Corporation) has taken on some new large-load interconnections reflects exactly this change. Whether the first 1,500 MW event in Korea will happen, and what exactly it will look like, no one knows yet.
There is an old expression in the power industry. “Electricity is the laziest guest. It always takes the shortest path.” For a hundred years, load was a guest. Now it is starting to speak up. A story that began, in the U.S. East, at 7 PM on that evening.