By Max Desruisseaux, Principal Power Systems Engineer, MRO

NERC, its Regional Entities, and registered entities have analyzed a series of recent bulk power system (BPS) disturbances that resulted in widespread, customer-initiated load reductions from large loads. In multiple events, most occurring in 2024 and 2025, more than 1,000 MW of large-load output was unexpectedly reduced. These incidents closely track the rapid increase in large-load penetration across the BPS, reinforcing concerns about the cumulative reliability impact.

Emerging large loads have grown substantially in recent years, with forecasts projecting that data centers alone could account for up to 12% of total U.S. electricity consumption by 2028, compared to 4.4% in 2023. Beyond their scale, these loads present unique operational challenges. Their electrical characteristics, including rapid demand fluctuations, cyclical ramping, and sensitivity to voltage disturbances, differ markedly from traditional load profiles. Compounding the issue, industry operating experience with this type of demand remains limited.

To better understand and address these risks, NERC established the Large Loads Task Force (LLTF) in August 2024. Building on this work, NERC released a white paper in July 2025 titled Characteristics and Risks of Emerging Large Loads. The paper identifies three high-priority risk categories associated with large-load integration:

In parallel, NERC issued an alert titled Industry Recommendation Large Load Interconnection, Study, Commissioning, and Operations. The purpose of this alert is to address reliability risks observed from analyzed large-load behavior and to assess the current state of industry preparedness as large-load penetration continues to grow.

The alert focuses on evaluating industry practices related to large-load dynamic modeling and simulation, interconnection requirements, study processes, and commissioning procedures. Findings from this assessment will help identify gaps in current practices and inform additional actions necessary to mitigate observed reliability risks. The results of this assessment will be published in a forthcoming report based on the alert data.

As emerging large loads continue to reshape electricity demand, NERC’s findings make clear that proactive planning, enhanced modeling, and close coordination between load owners and system operators will be essential. Addressing these challenges now will be critical to maintaining the reliability and stability of the bulk power system in the years ahead.

The alert is being distributed to entities registered with following responsibilities:

The Alert includes five recommendations as well as a questionnaire and an accompanying data submission worksheet.

The recommendations are as follows:

Recommendation 1: TOs should establish clear facility design and performance criteria in their interconnection requirements for Large Loads to mitigate the reliability risk posed by their expected behavior during normal operations and in response to System Disturbances. As part of these requirements, TOs should also require installation of high-speed disturbance data capture devices to monitor and assess the operational performance of Large Loads (e.g., Phasor Measurement Units (PMU)). Where relevant, DPs are also recommended to include these same criteria and disturbance monitoring devices. These interconnection requirements should be informed by the actions taken by the TP and PC in response to Recommendation 2.

Recommendation 2: TPs and PCs should establish a comprehensive interconnection and system-wide study process using steady state, dynamic, and short-circuit models to assess reliability impacts of Large Loads. This process should be implemented through the TO actions in Recommendation 1.

Recommendation 3: TOs should enhance their load commissioning activities to establish a comprehensive commissioning process that ensures operational readiness for Large Loads

Recommendation 4: TOs should establish operating protocols and the necessary communication infrastructure to support reliable ongoing operations after Large Load facilities enter commercial operations.

Recommendation 5: TPs, RPs, and PCs should, in consultation with their appropriate regulatory bodies, identify and implement a process to include Large Loads into their Long-Term Transmission Planning Horizon Demand forecasts as well as their Near-Term Transmission Planning Horizon Demand forecasts.

Reporting responses to the questions as well as the data submission worksheet are required to be submitted via the NERC Alert System by January 28, 2026, Midnight Eastern.

To view the alert please log in to the NERC Secure Alert System (https://www.nercalerts.com).

Additional resources:

• Large Loads Action Plan
• Characteristics and Risks of Emerging Large Loads
• Incident Review and Guidance on Voltage-Sensitive Large Load Integration
• Industry Recommendation – Large Load Interconnection, Study, Commissioning, and Operations