Notification of revised ISO operating procedures 3100, 3140, 3140A, 4420C, and 4420E

The California ISO (ISO) has revised the operating procedures referenced below.

3100 Establishing System Operating Limits for the Operations Horizon, version 8.3, effective Oct. 1, 2026.

Updated versions of North American Electric Reliability Corporation (NERC) PRC-024, effective 10/01/26. Included CAISO acronym with first instance of California ISO, defined Western Electricity Coordinating Council (WECC) and various other terms with first instance, and minor grammar and punctuation edits.

3140 TOP-003 TOP (Transmission Operator) - BA (Balancing Authority) Data Request and Specification Guidelines, version 6.1, effective Oct. 1, 2026.

Updated version of NERC Standard TOP-003, effective 10/01/26. Removed history prior to five years.

3140A TOP-003 TOP - BA Data Request and Specifications for Data Provision, version 6.9, effective Oct. 1, 2026.

Details tab: Updated data requests 6.13 and 6.14 for Geographic Information System (GIS) Template and lowered voltage to 69 kV. 

Version History tab: Removed history prior to five years.

4420C System Emergency Notice Templates, version 11.3, effective Oct. 1, 2026.

Annual Review: Very minor formatting and removed history prior to five years. No other content changes required at this time.

4420E Allowable Maintenance Activities During Restricted Maintenance Operations, version 13.4, effective Oct. 1, 2026.

Annual Review: Very minor formatting and removed history prior to five years. No other content changes required at this time.

The 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.