EDISON INTERNATIONAL

Major Transmission Projects

A summary of SCE's most significant transmission and substation construction projects is presented below. The timing of the projects below is subject to timely receipt of permitting, licensing, and regulatory approvals.

1 Direct expenditures include direct labor, land, and contract costs incurred for the respective projects and exclude overhead costs that are included in the capital expenditures forecast discussed in "Management Overview—Capital Program."

2 Direct expenditures were adjusted for inflation with no change to the scope of the project.

3 In June 2023, SCE filed an amended application for a certificate of public convenience and necessity ("CPCN") with technical design modifications and engineering refinements to the proposed project that decreases project costs and reduces GHG emissions. Accordingly, the direct expenditures of the project are estimated to be reduced from $486 million to $472 million. SCE is unable to predict the final project costs for the Alberhill System Project.

Riverside Transmission Reliability Project

The Riverside Transmission Reliability Project is a joint project between SCE and Riverside Public Utilities ("RPU"), the municipal utility department of the City of Riverside. While RPU will be responsible for constructing some of the project's facilities within Riverside, SCE's portion of the project consists of constructing upgrades to its system, including a new 230 kV substation; certain interconnection and telecommunication facilities and overhead transmission lines in the cities of Riverside, Jurupa Valley and Norco and in portions of unincorporated Riverside County. In May 2022, the Riverside City Council ("RCC") voted to investigate alternatives to the CPUC approved project. Consequently, SCE suspended all major activities on the project. In January 2023, the RCC voted to establish a working group to pursue funding for additional undergrounding. In October 2023, the City of Norco filed a petition for modification ("PFM") to modify the CPUC decision approving the project and reopen the record to reconsider full undergrounding. In November 2023, SCE filed a response opposing the PFM. In March 2024, the CPUC denied the PFM. In May 2024, the RCC voted to move forward with the original scope of the project and SCE restarted its work on the project. In July 2024, SCE initiated construction bid solicitations with awards expected in the first half of 2025.

Alberhill System Project

The Alberhill System Project consists of constructing a new 500 kV substation, two 500 kV transmission lines to connect the proposed substation to the existing Serrano-Valley 500 kV transmission line, telecommunication equipment, and subtransmission lines in western Riverside County. The project was designed to meet long-term forecasted electrical demand in the proposed Alberhill System Project area and to increase electrical system reliability and resiliency. In April 2018 and July 2018, the CPUC issued a proposed decision and an alternate proposed decision, both denying SCE's ability to construct the Alberhill System Project based on a perceived lack of need. SCE filed comments on both proposed decisions requesting that the CPUC grant the CPCN for the Alberhill System Project. In August 2018, the CPUC issued a decision that did not deny or approve the Alberhill System Project but directed SCE to submit supplemental information on the Alberhill System Project, including, but not limited to, a load forecast and cost benefit analysis of several alternatives to the proposed project. In January 2020, SCE submitted a supplemental analysis to the CPUC for the Alberhill System Project including several alternatives to the proposed project as well as an update to the original project cost. In June 2023, SCE filed an amended CPCN with technical design modifications and engineering refinements to the proposed project that decrease project costs and reduce GHG emissions. In June 2024, the CPUC issued an addendum to its 2017 Final

Environmental Impact Report, concluding its California Environmental Quality Act review. The project is now seeking final CPUC approval to begin construction. SCE is expecting the final CPUC decision in the second half of 2025.

Approximately 48% of the Alberhill System Project costs spent to date would be subject to recovery through CPUC revenue and 52% through FERC revenue. In October 2017, SCE obtained approval from the FERC for abandoned plant treatment for the Alberhill System Project, which allows SCE to seek recovery of 100% of all prudently incurred costs after the approval date and 50% of prudently incurred costs prior to the approval date. As of December 31, 2024, SCE had incurred approximately $69 million of capital expenditures, which excludes land costs that may be recovered through sale to a third party and includes overhead costs, of which approximately $48 million may not be recoverable if the project is cancelled.

Eldorado-Lugo-Mohave Upgrade Project

The Eldorado-Lugo-Mohave Upgrade Project will increase capacity on existing transmission lines to allow additional renewable energy to flow from Nevada to southern California. The project would modify SCE's existing Eldorado, Lugo, and Mohave electrical substations to accommodate the increased power flows from Nevada to southern California; increase the power flow through the existing 500 kV transmission lines by constructing two new capacitors along the lines; raise transmission tower heights to meet ground clearance requirements; and install fiber optics on the transmission lines to provide communications between existing SCE substations. In August 2020, the CPUC approved the CPCN for the project.

Construction for the project began in November 2020. The total costs for the Eldorado-Lugo-Mohave Upgrade Project are expected to exceed amounts currently approved in the CPCN granted by the CPUC due to delays in regulatory approvals, contractor performance issues, supply chain constraints, COVID-19 impacts, and the availability of CAISO outage windows. In May 2023, SCE filed a PFM of the decision that approved the project to increase the maximum reasonable and prudent cost for the project, which increased the direct expenditures from $247 million to $319 million. SCE expects the project to be in service in 2025, subject to the completion of environmental agency review of the mitigation work. Additional work after the in-service date is required to mitigate the impact of the project on nearby natural gas transmission lines. SCE's current estimate of the additional work is $64 million. SCE anticipates filing a second PFM or amending the existing PFM to address the additional costs of the mitigation work once the scope and cost of this work is finalized.

Utility Owned Storage Projects

In October 2021, SCE contracted with Ameresco, Inc. ("Ameresco") for the construction of utility owned energy storage projects at three sites in SCE's service area with an aggregate capacity of 537.5 MW, consisting of a 225 MW project, a 200 MW project, and a 112.5 MW project, and an in-service date of August 1, 2022. The 200 MW and 112.5 MW projects went in-service during the third quarter of 2024, and Ameresco has advised SCE that it currently expects the 225 MW project to be in-service by the first quarter of 2025. SCE believes that there is risk of delay beyond Ameresco's projected in-service date.

In April 2022, SCE received aforce majeure event notice from Ameresco in which Ameresco asserted that both manufacturing delays related to COVID-19 shut-downs in China and new shipping restrictions imposed by Chinese governmental authorities were then impacting the supply of batteries from China necessary for timely completion of the projects. Ameresco subsequently supplemented itsforce majeure notice noting additional supply chain issues related to COVID-19. Permitting delays and engineering issues and certain changes requested by SCE also impacted the projects in 2022. In January 2023, SCE received aforce majeure event notice from Ameresco in which Ameresco asserted that severe winter storms in Southern California had impacted the timely completion of the projects.

In April 2023, Ameresco discovered damage to some of the equipment at the 225 MW project. Ameresco has sent SCE a notice of potential force majeure event and has concluded that the damage was caused by soil heave and that the soil heave was caused by extreme rainstorms at the project site in the winter of 2022 – 2023. Ameresco is performing corrective action in response to the damage discovered in 2023.

SCE is continuing to evaluate theforce majeure event notices and is awaiting additional information from Ameresco on the underlying events. If there is a valid force majeure event under the contracts with Ameresco, subject to certain conditions, the project schedules and any related triggers of liquidated damages may be extended, and the contract prices may be increased to account for the impact of theforce majeure event.

SCE currently expects these storage projects to result in $1.0 billion of capital expenditures of which approximately $800 million has been incurred, as of December 31, 2024. SCE also expects to receive in aggregate approximately $380 million of tax credits available under the IRA for all three projects, which will accrue to the benefit of its customers (see "Notes to Consolidated Financial Statements—Note 8. Income Taxes" for further information). Because Ameresco did not achieve an in-service date of August 1, 2022, SCE is entitled to liquidated damages under the terms of the contracts subject to any relief Ameresco may be entitled to under the contracts, including any relief for any valid force majeure events. Once triggered, delay-related liquidated damages accrue daily for up to 60 days up to a maximum of $89 million in aggregate for all three projects.

Ameresco has obtained surety bonds to secure its obligations to complete the construction of the projects, and is also required to obtain surety bonds or letters of credit after completion of the projects to secure its performance obligations, including its warranty obligations. If Ameresco is unable to fulfill its obligations and the amounts available under any surety bonds or letters of credit are insufficient or the issuer of any such surety bonds or letters of credit disputes coverage or otherwise does not perform or pay for the performance of Ameresco’s obligations, SCE will incur additional costs beyond its contractual obligations.

In December 2021, the CPUC approved recovery of the capital expenditures and establishment of a balancing account for the associated revenue requirement, which have been reflected in rates beginning in the first quarter of 2022. Authorized revenue requirements have been and will continue to be included in the annual ERRA review proceeding and can only be disallowed upon a finding that SCE failed to prudently administer the contracts.