In May, we wrote that the Federal Energy Regulatory Commission (FERC) had committed to act by the end of June 2026 on its large load interconnection proceeding, and we flagged three open questions to watch: the federal-state jurisdictional line, how the costs of new infrastructure would be allocated, and how FERC would define a “large load.” On June 18, FERC acted, but it did not hand down the single national rule many expected. Instead, it issued six tailored show cause orders, one to each regional grid operator under its jurisdiction.

What FERC Issued on June 18

Rather than finalize a rule in Docket No. RM26-4-000, FERC opened six separate proceedings under Section 206 of the Federal Power Act directed at the ISOs (Independent System Operators) and RTOs (Regional Transmission Organizations):

• PJM: Docket No. EL26-67
• Southwest Power Pool (SPP): Docket No. EL26-68
• New York ISO (NYISO): Docket No. EL26-69
• Midcontinent ISO (MISO): Docket No. EL26-70
• California ISO (CAISO): Docket No. EL26-71
• ISO New England (ISO-NE): Docket No. EL26-72

Each order preliminarily finds that the region’s existing tariff appears unjust and unreasonable because it does not account for the way data centers and other large loads connect to and use the transmission system. Each grid operator…