You can raise a modification – or mod – when you want to propose a change to any part of the SQSS. 

For more information or for help raising an SQSS modification, please contact [email protected].

Search for any current or concluded modifications by name or ID. You can sort mods by ID, name, status or date of update. Or filter according to status.

Views reference
Modification status
ID Name Status Last Updated Sort ascending
GSR031 GSR031: Introducing Competitively Appointed Transmission Owners Current
Establishing ISOP in industry codes 2024 Establishing ISOP in industry codes 2024 Current
GSR024 GSR024: National Grid Legal Separation Changes Concluded
GSR023 GSR023: Clarification of the N-1-1 Requirements and minor housekeeping change Concluded
GSR008 GSR008: Regional Variations and Wider Issues Concluded
GSR025 GSR025: Updating the SQSS to reflect the recent modification to Engineering Recommendation P28 Concluded
GSR010 GSR010: Review of Onshore Entry Criteria Concluded
GSR026 GSR026: Adding Non- Standard Voltages to the SQSS Concluded
GSR011 GSR011: Review of Offshore Networks Concluded
GSR027 GSR027: Review of the NETS SQSS Criteria for Frequency Control that drive reserve, response and inertia holding on the GB electricity system Concluded

More about modifications

Modification Tracker

Our Tracker gives you the latest details on current code modifications including the purpose and the stakeholders it affects, as well as panel comments and where it is in the review process. It is published on the 7th (or next working day) of each month.

Modification Proposal Form

If you're thinking about raising a modification, please get in touch with us. Our experts can give you advice on your Proposal, explain how the modification process works and help to answer any questions you may have. When we receive your Proposal, we'll check it through and work together to make sure it's easy to understand.


Once you've been in touch and are ready to write your Proposal paper, send it to us by the monthly modification submission date which you can find on our Calendar.