TL;DR · 30-second read
The Short Version
On July 22, an ordinary electrical fault on a power line in northern Virginia caused a cluster of data centers, the buildings full of computers that run the internet, to disconnect from the grid almost at once.
In minutes, about 4% of all the electricity being used across 13 states and Washington, D.C. vanished from the system.
The organization that runs that grid says the data centers were too jumpy. It is now considering rules requiring them to stay connected through brief power glitches. If those rules arrive, how a data center reacts to a glitch could decide whether it gets connected at all.
Utility Dive reported that PJM Interconnection, the grid operator for 13 Mid-Atlantic and Midwest states and the District of Columbia, is considering new interconnection reliability requirements for “computational loads” such as data centers and crypto-mining facilities. The requirements under consideration include “ride-through” standards, which require equipment to stay connected through brief voltage and frequency disturbances rather than disconnecting.
The trigger was a July 22 event in which about 3,800 MW of data center load in northern Virginia tripped offline in two waves after a fault on a 230-kV transmission line in Dominion Energy’s zone. PJM’s total load fell about 3.8%, from 99,984 MW to 96,205 MW. PJM called it the largest such event in its history.
Executive Summary
PJM is evaluating whether to expand its reliability requirements for large computing loads after data centers disconnected from the grid in response to what its Operating Committee chair called “a normally cleared fault.” In other words, the grid did what it was supposed to do, and the data centers dropped off anyway. PJM staff told an August 6 Operating Committee meeting that the facilities appear to be disconnecting too early.
This matters because it shifts part of the grid-reliability burden onto the load side. Until now, the obligation to stay online through disturbances has fallen mainly on power plants. PJM’s position is that a data center cluster large enough to remove nearly 4% of system demand in minutes now needs the same kind of behavioral rules. As David Souder, PJM’s executive director of system operations, put it, those requirements need to be “in place before the load comes on the system.”
The timing also matters. The North American Electric Reliability Corp. (NERC) is building national standards for computational loads under a Federal Energy Regulatory Commission directive. PJM said, however, that NERC will not address voltage and frequency ride-through until sometime next year. That leaves PJM weighing whether to act in the meantime.
How a Routine Fault Became a 3,800 MW Problem
Transmission faults happen constantly. A line gets struck by lightning or contacts a tree, protective relays isolate it within a fraction of a second, and voltage briefly sags on nearby parts of the network before recovering. Power plants are expected to “ride through” that sag, meaning they stay connected and keep producing. Data centers are generally built with the opposite instinct. Their electrical systems are designed to protect servers from bad power, so when voltage moves outside a set tolerance window, they switch to batteries and on-site generators and stop drawing from the grid.
For a single facility, that is sensible engineering. For a cluster, it becomes a system event. When thousands of megawatts of demand leave the grid at the same moment while generation keeps running, supply suddenly exceeds demand. Frequency and voltage swing, and the operator has to rebalance quickly. PJM said the July 22 event caused “a high imbalance between generation and load” and large swings in both voltage and frequency, and that it dispatched reactive power resources to bring system voltage down. PJM’s Operating Committee chair, Emanuel Bernabeu, described the data centers as “too sensitive to the kind of voltage that they like.”
The Event Sizes Are Growing Faster Than the Rules
PJM listed two earlier events in the same Dominion zone. Each caused a sudden load transfer of about 1,500 MW, one in 2024 and one in 2025. The July 22 event was roughly two and a half times that size. Three incidents in one region do not make a statistical trend, but the direction is consistent with how northern Virginia is building out: more and larger facilities, clustered on the same transmission network and often reacting to the same disturbance at once. For scale, 3,800 MW is on the order of the output of three large nuclear reactors.
The grid handled it. PJM said it brought its Area Control Error, the running measure of the mismatch between supply and demand, back within limits in nine minutes, against a NERC standard of 30 minutes. That is a good operational result, and it should not be read as a near miss. The concern PJM raised is forward-looking: each new facility connected under current practice adds to the amount of demand that could disappear in a single disturbance. At some point the operator has to either hold more balancing capacity in reserve or require the load to behave differently. PJM’s move signals it prefers the second option.
Ride-Through Moves From Design Choice to Condition of Connection
This is the substance behind the headline. PJM is framing the fix as an interconnection reliability requirement, a condition attached to connecting to the grid, rather than a best-practice guideline. Souder’s remark that requirements must be in place “before the load comes on the system” points to the interconnection queue as the enforcement point. If PJM follows through, projects now in development would need to show that their electrical design keeps them connected through a normally cleared fault. Retrofitting that behavior after energization is harder and more contested.
The practical effects would be felt in specific places. Developers and colocation operators would need to revisit the voltage and frequency tolerance settings on their uninterruptible power supplies and switchgear, and possibly the hardware itself. Hyperscale tenants would need to accept that their facilities ride out disturbances their servers were previously shielded from. Equipment vendors whose systems can demonstrate grid-friendly behavior would gain a selling point. Utilities such as Dominion, whose zone hosts the world’s largest data center cluster, would gain a clearer technical basis for connection studies. The rules would cover crypto miners too, because PJM used the broader category of “computational loads.” Mining loads are generally more flexible about interruption, but they are no less able to trip off in a block.
There is a real engineering tradeoff, and it deserves an even-handed hearing. Data center operators set tight tolerances to protect equipment and meet uptime commitments to customers, and loosening them carries risk for the operator. PJM’s argument is that the risk of undisciplined load, which falls on everyone connected to the grid, now outweighs the private risk. Where the thresholds land, and whether PJM offers alternatives such as coordinated or staggered transfer settings, will determine how costly the change becomes.
A Gap Between Regional Urgency and National Standards
NERC is scheduled to finalize registry criteria and initial reliability standards for computational loads by December 31, and to produce a plan by March for additional standards. According to PJM, ride-through for minimum voltage and frequency will not be addressed until sometime next year. Meanwhile, Northern Virginia continues to add capacity. That leaves PJM choosing between acting regionally now and risking a mismatch with a later national standard, or waiting and connecting more load under today’s practices. Wharton’s reference to “existing and future industry ride-through standards and practices” suggests PJM intends to align with NERC where it can, without waiting for NERC to finish.
Background
Northern Virginia, largely within Dominion Energy’s service zone, hosts the largest concentration of data centers in the world. Rapid growth in data center demand there and elsewhere in PJM’s 13-state footprint has made large computing loads a central grid-planning issue. PJM has reported sudden data center load transfers of about 1,500 MW in both 2024 and 2025, and NERC issued alerts on sudden data center load losses earlier in 2026, including a Level 3 alert in May calling for mandated actions.
Grid reliability rules in North America are set by NERC and approved by the Federal Energy Regulatory Commission. Regional operators such as PJM can add their own interconnection requirements. Historically those rules focused on generators. The rise of very large, clustered loads has prompted FERC to direct NERC to develop registry criteria and reliability standards specifically for computational loads. Source: PJM eyes data center, crypto reliability requirements after 3.8 GW of load trips offline (Utility Dive, August 12, 2026), covering PJM’s response to the July 22 northern Virginia load-loss event.Sources