MISO Large Load Requirements: What the FERC Filing Asks

MISO wants every new 50 MW load on its transmission system to come with operating data, and data center loads with 25 MW or more of IT equipment to come with measurement hardware, ramp limits and ride-through performance. The MISO large load requirements were filed at FERC on August 28, 2026 in docket ER26-3650, with a requested effective date of December 4, 2026. As of November 7, the Commission has not ruled.

That status matters more than any single provision. A utility or developer can plan around a proposal, but it cannot yet write a compliance spec against one. Much of the operating detail is also left to a future Business Practices Manual rather than the tariff itself.

This piece walks through what the filed tariff says, who carries the cost, which projects are exempt, and where the separate zero-injection proposal stands.

Large Load and Computational Load Definitions

The filed definitions, in MISO’s proposed tariff, set two tiers.

• Large Load: demand of 50 MW or more associated with a facility or group of facilities at a single substation, behind one or more points of withdrawal from the transmission system, owned, operated or controlled by a single entity or by a group that coordinates the load’s profile. Load used exclusively to charge an electric storage resource is excluded.
• Computational Load: a Large Load made up of 25 MW or more of demand from information technology equipment, such as servers, storage and networking hardware.

The tiers matter because the requirements stack. Every Large Load faces the data, modeling, telemetry, forecast and audit rules. The PMU, ramp and ride-through rules apply to Computational Load. A 60 MW industrial plant and a 60 MW data center are both Large Loads; only the data center faces the hardware-heavy half.

The Four MISO Large Load Requirements

MISO’s transmittal letter groups the proposal into four requirement types.

1. Visibility. Facility information, electrical models, real-time telemetry, monitoring and forecasting. The proposed telemetry section requires real-time telemetry before the later of the service commencement date or September 1, 2027, plus individual metering for the Large Load and any behind-the-meter generation serving it, at thresholds the manual will set.
2. Phasor measurement units. High-resolution, time-synchronized measurement for Computational Load, used for model validation and disturbance analysis.
3. Ramp. Limits on how fast a Computational Load can raise or lower demand during stable-state transitions. MISO proposes initial up- and down-ramp limits of 30 MW per minute, measured in aggregate across the load’s points of withdrawal, with eligible generation or other resources allowed to provide ramp smoothing. The tariff leaves the process for setting each load’s limits to the manual, which will consider local planning criteria and let MISO authorize deviations.
4. Ride-through. The transmission customer must make sure the Computational Load stays connected and keeps operating through voltage and frequency disturbances, within performance criteria MISO will publish in the manual. Compliance applies at the point of withdrawal and may include evaluation, testing, modeling and monitoring.

The 30 MW per minute figure is a proposed starting point, not an effective rule, and the ride-through performance numbers are not in the tariff at all. MISO’s transmittal says the detailed ride-through criteria are described in its published Large Load Technical Compendium, which it will incorporate into the Business Practices Manual before the effective date. Anyone specifying controls or UPS behavior for a MISO data center today is designing to criteria that sit outside the tariff and have not been approved.

PMU Cost: Utility Side, Customer Pays

The PMU section is the clearest procurement signal in the filing. Under proposed Section 37A.5, before the later of the Large Load’s service commencement date or September 1, 2027, phasor measurement recording and communications equipment must be installed by the transmission owner, at the transmission customer’s expense.

The equipment goes on the transmission owner’s side of the point of withdrawal and becomes part of the owner’s interconnection facilities. Existing or planned relays or digital fault recorders can satisfy the requirement if they collect data at least at the PMU rate, are synchronized to a high-accuracy satellite clock, and sit on the owner’s side of the point of withdrawal.

For a transmission owner, that reads as a relay and recorder specification question on every new Computational Load interconnection: can the protective relays already in the design double as the measurement device? For the customer, it is a line item in the interconnection cost estimate. We saw a similar pattern in CAISO’s draft large load requirements, and the broader trend of load flexibility becoming an equipment spec.

Who Is Exempt: The Transition Rules

The proposed applicability section sorts loads into three buckets, keyed to December 4, 2026 and to an “MTEP/EPR Condition.” A project meets that condition if it was approved by the MISO Board in MTEP 2026 or an earlier MTEP, or was submitted for Expedited Project Review on or before June 18, 2026.

Bucket	Who	What applies
Fully exempt	Service commencement on or before December 4, 2026, for the portion with procured transmission service	No Section 37A requirements. A later cumulative increase of 25 MW or more, on a load that meets the MTEP/EPR Condition, moves that increment to partial treatment.
Partially exempt	No service before December 4, 2026, but meets the MTEP/EPR Condition	Data, modeling, telemetry, forecast, PMU and audit rules. Exempt from ride-through and ramp.
Non-exempt	Does not meet the MTEP/EPR Condition	All applicable requirements

A second group sits under the partially exempt heading but gets no exemption: loads tied to transmission projects submitted for Expedited Project Review from June 19 through October 31, 2026 face all requirements, but MISO may waive ride-through if exemption would not have an adverse reliability impact and compliance would cause significant costs. That is a case-by-case waiver, not a blanket exemption.

MISO also keeps an override. Paragraph 3 of the proposed applicability section lets MISO require compliance with any or all of the requirements, even for an exempt load, if it determines that the load’s operation has a material adverse effect on transmission reliability. An exemption is a starting position, not a guarantee.

Where the Filing Stands

FERC eLibrary for ER26-3650, checked November 7, 2026, shows answers filed in October and early November, including MISO’s own October 13 answer to comments and protests, a Coalition of MISO Transmission Customers answer, a Central Municipal Power Agency Services answer, and a November 3 answer from the Data Center Coalition. It shows no Commission order. Until one issues, the December 4 date is a request.

The filing also responds to FERC’s June 2026 show-cause proceeding on large load service, which we covered in our six-RTO show-cause explainer. PJM’s parallel filing has already drawn an October 9, 2026 FERC order in docket ER26-3515 accepting its tariff revisions in part and rejecting them in part; our PJM read covers what survived. Do not assume MISO’s outcome will match.

The Separate Zero-Injection Proposal

MISO filed a different proposal on August 18 in docket ER26-3552, for a Zero Injection Generation Resource: generation that serves load interconnecting at the same substation and voltage level without injecting energy onto the transmission system. As FERC staff summarized it, the proposal adds a 90-day study process, a pro forma Zero Injection Generator Interconnection Agreement, and market and resource adequacy participation limited to serving the associated load.

On October 9, 2026, FERC’s Office of Energy Market Regulation told MISO the filing was deficient and asked for more information within 45 days. Staff’s questions include how the proposal meets the purposes of FERC’s generator interconnection rules, unclear cross-references in the proposed tariff, whether study results will be publicly posted, and whether a zero-injection resource’s market offers must be below, or may equal, its associated load’s demand. A deficiency letter is a request for information, not a rejection. It does mean the pathway is further from approval than its requested October effective date suggested.

What Buyers and Planners Can Do Now

• Place each project in a transition bucket now. The MTEP/EPR Condition and the December 4 service date decide which requirements apply. Get that classification confirmed by the transmission owner in writing.
• Price the PMU line, and ask about existing relays. If the protective relays or fault recorders in the substation design meet the stated data rate and timing, they may satisfy Section 37A.5. Ask the transmission owner before buying separate hardware.
• Do not lock controls or ride-through specs to the 30 MW per minute figure or to the current technical compendium. Wait for the order and the manual.
• Treat zero injection as unresolved. It is a pending study pathway under a deficiency letter, not a queue bypass.

Related Reading

• CAISO Large Load Requirements: Reading the September Draft
• PJM Large Load Curtailment Rule: What FERC Kept
• Data Center Load Flexibility Is Now an Equipment Spec

Definitions, requirements and transition rules are from MISO’s August 28, 2026 filing in FERC Docket ER26-3650-000 (transmittal letter and clean tariff sheets, Section 37A), opened November 6 and 7, 2026. Zero-injection details are from FERC staff’s October 9, 2026 deficiency letter in Docket ER26-3552-000. Docket status is as of a FERC eLibrary search on November 7, 2026.

FERC’s order, and the manual that follows it, will decide the real spec. The Feeder is our free weekly digest of the regulatory and supply signals that change what utility buyers specify.

Frequently Asked Questions

What counts as a Large Load under MISO's proposal?

MISO's filed tariff defines a Large Load as 50 MW or more of demand at a facility or group of facilities at a single substation, behind one or more points of withdrawal, owned or controlled by one entity or a coordinating group. Load used only to charge an electric storage resource is excluded. A Computational Load is a Large Load with 25 MW or more of demand from IT equipment such as servers, storage and networking hardware.

Who pays for the phasor measurement units?

Under proposed Section 37A.5, the transmission owner installs the PMU equipment on its side of the point of withdrawal, at the transmission customer's expense. Location on the utility side does not mean the utility absorbs the cost.

Are MISO's large load requirements in effect?

No. MISO asked FERC to make them effective December 4, 2026. As of November 7, 2026 the docket shows answers from MISO and other parties but no Commission order. The requirements are proposed, not approved.