Mesa–Mira Loma 500kV Underground Third Cable 

The Mesa–Mira Loma 500kV Underground Third Cable project in Chino Hills is part of a statewide transmission plan approved by the California Independent System Operator (CAISO) in May 2023. 

This project represents a critical investment to support California’s growing energy needs, especially as the state continues to expand its use of clean and renewable energy sources. 

When SCE designed and constructed the Mesa-Mira Loma facility, future growth was built into the plan. Today, SCE is advancing that vision by installing additional underground cables to enhance system capacity, flexibility and reliability as electricity demand increases, driven in part by California’s clean energy transition, including expanded wind, solar and battery storage resources. 

The project will primarily take place within approximately 3.7 miles of existing right-of-way.

About CAISO

CAISO manages the flow of electricity across high-voltage, long-distance power lines that make up 80 percent of California's and a small part of Nevada's grid. The nonprofit public benefit corporation also operates a competitive wholesale energy market and conducts transmission planning to identify grid expansion needs.
 

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SCE’s transmission line right-of-way (ROW) is an active utility corridor. During upcoming construction activities, access within the ROW may be restricted or temporarily closed. Please observe all posted signage and guidelines to help maintain a safe environment for both the public and crews. This upgrade work will not affect your electrical service and customer outages are not expected as a result of this construction.

Stay Informed

This webpage will serve as the primary source for project updates, including construction activities, schedule changes and important notices. Community members and customers are encouraged to check back regularly for the latest information.

Contact Us

If you have questions or would like more information, please email sceprojects@sce.com.