Transmission System Code (TSC)

Sets out the minimum standards that an electricity transmitter must meet in designing, constructing, managing and operating its transmission system. The code also sets out the requirements, standards, terms and conditions of a transmitter’s obligations to connect consumers to the transmission system, including performance standards, technical requirements and expansions and connections.

Industry Codes/Rules
Last revised
August 2, 2023

Related documents

Amendments to the Transmission System Code

8. Amendments to ensure the most cost effective investments are made to replace major transmission voltage assets when they reach end of life (EOL) and need to be replaced, as part of the regional planning process. These changes came into force on August 2, 2023 (EB-2020-0176). More information | August 2, 2023 version (pdf)

7. Amendments that are aimed at ensuring the Cost Responsibility rules for load customers in the TSC and DSC are better aligned and facilitate the implementation of Regional Plans. These changes came into force on December 18, 2018 (EB-2016-0003). More information | December 18, 2018 version (pdf)

6. Amendments to avoid conflicts with NERC standards and NPCC criteria in transmission system operations. Design specifications were also clarified and brought in line with current good utility practice. These changes came into force on April 30, 2018.

5. Amendments to implement the OEB’s policies related to Protecting Privacy of Personal Information and the Reliable Operation of the Smart Grid in Ontario that came into force on March 15, 2018. More information

4. Amendments to implement the OEB’s policies related to Regional Infrastructure Planning came into force on August 26, 2013. More information

3. Amendments to revise the definition of the term “Supporting Guarantee” as it appears in Appendix 1A and Appendix 1B came into force on June 10, 2010. More information

2. Amendments that address issues associated with “enabler facilities” that connect renewable generation facilities to the transmission grid came into force on October 20, 2009. More information

1. Amendments designed to clarify and, in some cases, modify the rights and obligations of transmitters and transmission customers came into force on July 25, 2005. More information