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Public utilities

Oncor Electric Delivery Company LLC Seeks to Amend Certificate of Convenience and Necessity for the Rockhound Switch to Connell Switch 345-KV Transmission Line

Strategic Insights

— 2 min read

On September 16, 2025, Oncor Electric Delivery Company LLC filed an application to amend its certificate of convenience and necessity for the Rockhound Switch to Connell Switch 345-kilovolt transmission line project in Midland and Martin counties, Texas. The Public Utility Commission of Texas must render a decision within 180 days, and Oncor is taking concurrent actions to assist in meeting this deadline, including filing direct testimony, requesting immediate referral to the State Office of Administrative Hearings, and providing responses to the Commission's standard Order No. 1 questions.

Key Takeaways:

  • Oncor's reliability assessment has observed thermal overloads on the 345 kV and 138 kV transmission systems beginning in summer 2025, and by 2030, post-contingency loading on Oncor's Rockhound Switch transformers will increase to as much as 132% of their emergency ratings if the Project and related system upgrades are not in service.
  • Oncor has active interconnection requests for approximately 1,100 MW of customer load that are dependent on the Project, including over 300 MW contracted under executed Facilities Extension Agreements and an additional 500 MW of new load that will be executed soon.
  • ERCOT has not recommended the Project in its annual report, but Oncor still believes it is necessary to alleviate existing and potential transmission and distribution constraints and system needs within ERCOT.
  • Oncor is requesting immediate referral to SOAH to facilitate a more efficient processing of the Application and ensure timely return of this docket for final disposition.
  • The Project includes three components of Oncor's Connell 345/138 kV Switch and Connell-Rockhound 345 kV Double-Circuit Line Project, a Tier 1 transmission project filed with ERCOT's Regional Planning Group on June 18, 2024.
  • ERCOT informed Oncor in August 2025 that it does not anticipate issuing an independent review of the Project until November 7, 2025, which would result in the Project being placed in service too late to meet the interconnection requests of customers who have been waiting since 2024 or earlier.

Statistics:

  • 132%: The projected increase in post-contingency loading on Oncor's Rockhound Switch transformers by 2030 if the Project and related system upgrades are not in service.
  • 1,100 MW: The approximate amount of customer load that Oncor has active interconnection requests for, dependent on the Project.
  • 300 MW: The amount of contracted customer load under executed Facilities Extension Agreements.
  • 500 MW: The additional amount of new load that Oncor will soon execute under a Facilities Extension Agreement.
  • 132 MW: The amount of customer load awaiting interconnection at the time the RPG submittal was finalized in early summer 2024.
  • 14 months: The time it took for ERCOT to inform Oncor that it does not anticipate issuing an independent review of the Project until November 7, 2025.

Sources:

  • Public Utility Commission of Texas - APPLICATION OF ONCOR ELECTRIC DELIVERY COMPANY LLC TO AMEND ITS CERTIFICATE OF CONVENIENCE AND NECESSITY FOR THE ROCKHOUND SWITCH-TO-CONNELL SWITCH 345-KV TRANSMISSION LINE IN MIDLAND AND MARTIN COUNTIES ONCOR ELECTRIC DELIVERY COMPANY LLC'S REQUEST FOR IMMEDIATE REFERRAL TO SOAH AND RESPONSES TO STANDARD ORDER NO. 1 QUESTIONS, filed September 16, 2025.

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