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National Grid filed a petition for approval of its partially interruptible service class pilot proposal, effective November 1, 2027.

“National Grid (“National Grid”, “NMPC”, or the “Company”) submits this petition for Commission approval of its Partially Interruptible Service Class Pilot Program (the “Pilot”). The Rate Case Order and Joint Proposal require the Company to file a petition with the Commission for its approval within two months of the submission of its proposal for the Pilot and prior to implementing a partially interruptible service class pilot program.”

“This petition outlines the design and program terms of the Pilot, while providing a summary of the costs, program benefits, and proposed recovery mechanism. This petition seeks to implement a two-year pilot program for a new service class limited to ten current Service Classification No. 8 (“SC‑8”) customers with at least one million therms of annual usage. The Pilot will feature partial interruptions, meaning that customers will be required to have primary point capacity (“PPC”) on upstream pipeline system up to a certain threshold to receive firm transportation service on the Company’s distribution system up to that threshold. Service provided beyond the threshold would be fully interruptible, and the customer would not be required to maintain PPC for interruptible deliveries.

The remainder of this petition details the program design, customer eligibility, operational protocols, pricing and penalties, PPC requirements, post-pilot rules, cost recovery, implementation timeline, evaluation plan, and the specific Commission approvals sought. Each element aligns with the structure described in Section 4.8 of the Joint Proposal and conforms to the Company’s tariffed interruptible framework, as applicable. The Company also addresses the written comments were submitted on April 1, 2026 by Multiple Intervenors and NRG Energy Inc. (“NRG”) in this proceeding.”

PROGRAM OVERVIEW AND CUSTOMER ELIGIBILITY

“The Company is proposing a two-year pilot for a partially interruptible service class with a minimum annual usage of at least one million therms. SC-8 serves the Company’s largest firm customers and requires annual usage of at least one million therms of annual usage. Therefore, the Company will seek voluntary participants from customers that are currently served on SC-8, which is currently approximately 70 customers. The SC-8 tariff has a provision that allowed customers to sign up for standby service from the Company, which is called a D1 election. Effective September 1, 2025, no new D1 elections are being granted to customers, but existing SC-8 D1 customers can keep their existing elections which may be reduced but may not be increased. Customers with D1 elections will be able to participate in the pilot, but the Maximum Peak Day Quantity (MPDQ) limit will include their D1 election plus their PPC. For example, if a customer’s MPDQ is 10,000 Dth, they would be limited to 50% during an interruption (5,000). If the customer currently has a D1 election of 1,000 Dth, they will only need to confirm PPC of 4,000 Dth from their marketer.

The two-year pilot would be limited to 10 customers that are served on the East Gate to address current system constraints. Customers would be required to maintain 50% of their MPDQ as primary point capacity and operate under usage limits set at 50% of MPDQ during interruptions, which the Company is proposing to ensure that there is a meaningful usage reduction at times when there are system constraints. Any marketer serving a customer participating in the pilot program would be required to have primary point capacity for 50% of their customer’s MPDQ. The Company is not proposing that customers participating in the pilot would be required to have an alternative fuel source and would only be required to curtail during a called interruption. While the Company believes that 50% of MPDQ is a reasonable proposal in this pilot program, the Company would be willing to reconsider based on stakeholder comments that will be filed in response to the Company’s proposal.”