The California Independent System Operator's Board of Governors approved the grid operator's large-load interconnection proposal on Oct. 28, 2026, according to the CAISO stakeholder initiative page. The proposal is CAISO's answer to the Federal Energy Regulatory Commission's show-cause order in Docket EL26-71. It sets the line for a "large load" at 50 megawatts at a single site. It also creates one curtailable service that lets big customers, data centers among them, connect before the grid upgrades they need are finished.
Two days after the vote, on Oct. 30, CAISO posted a second revised draft of the tariff language. That draft adds ride-through provisions written by the initiative's large load technical working group. The grid operator plans to file the package at FERC by Nov. 16, 2026.
Below is what the framework does, where it came from and where stakeholders disagreed.
Why is CAISO doing this?
FERC opened Docket EL26-71-000 with a show-cause order directed at CAISO. According to an analysis on Gravel2Gavel, a law-firm blog, the order also named a long list of transmission owners as respondents, including investor-owned utilities, municipal entities, transmission companies and the Western Area Power Administration.
The Gravel2Gavel analysis explains why the transmission owners are in the docket. CAISO does not offer traditional Order No. 888 network integration transmission service, and the analysis says transmission owners play a leading role in physical load interconnection. A framework for large loads in California therefore has to address the utilities and other entities that own the wires, not just CAISO.
The initiative began on Feb. 27, 2026, according to CAISO's stakeholder page. A draft final proposal and draft tariff language followed on Sep. 24, and a revised draft tariff came out on Oct. 26, two days before the board vote.
What counts as a large load?
CAISO's Sep. 24 draft final proposal defines a large load as an end user at a single site with a peak load of 50 MW or greater.
The document records that PG&E suggested a lower threshold of 20 MW during the process. CAISO kept the 50 MW figure. In laying out the options, the document notes that the Midcontinent Independent System Operator (MISO) proposed two classes: a 50 MW generic class and a 20 MW computational class. CAISO kept a single 50 MW threshold.
The proposal also cites the definition FERC suggested as potentially reasonable: a new commercial or industrial customer at a single site with a peak load of 50 MW or greater, interconnected at a voltage level above 69 kV and not part of a co-location arrangement.
How fast must studies happen?
Under the proposal, participating transmission owners must have load study procedures that finish within 60 to 90 days, a timeframe the document attributes to FERC. It also adds a new monthly review window for incoming large-load requests.
Not everyone thinks that schedule is realistic. According to mgrid.org's Oct. 30 report, Microsoft and other stakeholders questioned whether transmission owners can finish the studies in 60 to 90 days.
What is FILI?
The main new feature is the Flexible Interim Load Interconnection service, or FILI. The draft final proposal describes it as a curtailable interim connection. A large load can take power before the network upgrades it needs are complete, but its service can be cut back until those upgrades are done.
The draft final proposal calls for provisions governing the following from customers using FILI:
- hourly load forecasts,
- telemetry data, and
- equipment that lets CAISO remotely disconnect large loads when necessary to maintain reliability.
The approved framework has only that one flexible service. According to mgrid.org, the August straw proposal had floated a second option, a permanent flexible service known as FLIP, and the draft final proposal proposes only FILI. So the only flexible path is interim: a customer that wants firm service still has to wait for the upgrades to finish.
Who argued over the agreements?
Another dispute was over who signs the contracts. mgrid.org reports that CAISO expects the transmission owners to develop pro forma agreements covering large-load operations and cost recovery. San Diego Gas & Electric, the California Department of Water Resources and the California Public Utilities Commission asked CAISO to be a party to those agreements. According to mgrid.org, CAISO agreed that a consistent approach is needed but held that the provisions belong in the transmission owners' tariffs.
How much load is at stake?
Forecasts put the scale in context. Gravel2Gavel and mgrid.org both cite a California Energy Commission forecast of 1.8 GW of data center load growth by 2030. mgrid.org also reports a CEC figure of 4.7 GW by 2035, while Gravel2Gavel cites 4.9 GW by 2040.
Those numbers cover data centers only, not every customer that would fall under the 50 MW threshold. They come from the energy commission's forecasting, not from the CAISO tariff.
What changed after the vote?
The Oct. 30 second revised draft tariff language is labeled as responding to the Order to Show Cause. According to the stakeholder page, it includes ride-through provisions from the large load technical working group. It is the most recent draft tariff language the stakeholder page lists ahead of the FERC filing.
What Happens Next
CAISO's stakeholder page lists Nov. 16, 2026 as the date for the FERC filing of the large-load tariff language responding to the show-cause order in Docket EL26-71.
