Notification of revised ISO operating procedures 4420, 4510B, and 4510F

The California ISO has revised the operating procedures referenced below. 

4420 System Emergency, version 16.4, effective June 1, 2026. 

Annual Review: 

Section 3.6.1, Task 11: Provided more detail for clarity.

Minor formatting and grammar edits.

4510B Demand Response and UDC Interruptible Programs, version 7.7, effective June 1, 2026. 

Annual Review: No changes. 

4510F Reliability Demand Response Resource (RDRR) Daily Reporting Template, version 3.5, effective June 1, 2026. 

Annual Review: No changes. 

The California ISO’s operating procedures are available on the Operating Procedures webpage.

Please contact the CAISO/RC West Procedure Control Desk at ProcedureControl@caiso.com with any questions.