The Midcontinent Independent System Operator (MISO) has published a new set of requirements for large loads wanting to connect to the grid, as part of an initial response to the Federal Energy Regulatory Commission’s (FERC’s) show cause order.

MISO made several revisions to its Open Access Transmission, Energy and Operating Reserve Markets Tariff (OATT), according to an August 28 filing with FERC.

According to the filing, the new requirements address “visibility, ramp rate and disturbance ride-through requirements … along with transition provisions to minimize disruption to commercial arrangements,” which were all points raised as part of FERC’s show cause order.

MISO has asked for the revisions to be made effective December 4, 2026.

Show cause orders

Filed on June 18 under Section 206 of the Federal Power Act, FERC issued tailored show cause orders to the six US regional grid operators requiring them to justify why current tariffs for large loads remain “just and reasonable.”

If unreasonable, FERC asked grid operators to overhaul the processes by which they treat new large loads. As part of the show cause orders, FERC suggested five categories for grid operators to focus their reform on.

These were developing efficient transmission service application and study processes, preventing transmission cost shifting, accommodating behind the meter generation, providing new transmission services for flexible large loads and finally developing a process to study generating facilities servicing large loads.

MISO said that this show cause order “reinforced the value of MISO’s prior efforts with stakeholders … to develop critical solutions to help support the cost-effective, reliable and efficient integration of large loads.”

Prior to FERC’s show cause order, MISO was due to file plans of its Zero-Injection Generator Interconnection Agreement (ZGIA).

The ZGIA framework, which mirrors certain aspects of MISO’s ERAs process, would have allowed large loads to connect onsite generation without going through the standard interconnection queue.

Large load threshold

In addressing FERC’s show cause order, MISO laid out a definition of a “large load,” which it described as a “load with a demand of 50MW or more associated with any facility or aggregation of facilities located at a single substation.”

MISO described this threshold as a “reasonable and administratively clear starting point” that is “consistent with industry precedent.”

It also gave a definition for “computational load,” which it described as a large load exceeding a demand of 25MW stemming from information technology equipment.

MISO said this definition was necessary as computational loads, such as those coming from data centers, “may exhibit rapid and coordinated changes in demand.”

Tariff requirements

In order to satisfy MISO’s new large load requirements, customers will be required to provide the system operator with a large amount of continuously updated information, including one-line diagrams, load profiles and forecasts.

Additionally, customers must provide real-time telemetry for large-load projects, and individual metering will be required both for large loads and also any co-located behind the meter (BTM generation resources.

In terms of transitioning to the new tariff, MISO proposes to exempt any large load that enters service on or before December 4 from all new requirements.

The system operator also proposed to exempt large loads currently progressing via its Transmission Expansion Plan process from some of the new requirements.

MISO said that it would address remaining issues raised in FERC’s show cause order in “forthcoming large load proposals.”

NPM Interconnection queue data identified 217 pre-operational projects, across 32.82 GW, that reached an advanced stage in the 24-month period ending in June 2026.

NPM data is tracking 297 planned data centers across states in MISO.