1. Place your chosen image here. The four corners must just cover the arrow tips. For covers, the three pictures should be the same size and in a straight line. Mod 426 - Entry Overruns Transmission Workgroup July 5 th 2012

2. 2 Background  Modification 426 – Amendment to the NTS System Entry Overrun Charge raised to:  add 8* current MSEC firm reserve price (at that ASEP) as a bottom stop to the existing overrun calculation  to remove the potential for zero or no overrun charges to be generated  NGG gave a presentation at 7 th June Transmission Work Group and the following actions were received  Action 0426/001: Provide details of the instances of the overruns, demonstrating the volume involved and the overrun charge that would have applied with the proposed solution.  Action 0426/002: Provide an explanation of the costs and timescale of implementation.

3. 3 Entry Overrun Data YearNo. of instances of overruns incurring a zero / non overrun charge Maximum Overrun Quantity GWh Total Overrun Charges incurred Estimated *Total of Overrun Charges applied under modification 426 2008342.20£4,414 200995.60£8,757 20102710.70£10,953 2011617.10£13,324 * Based on current MSEC Reserve Prices

4. 4 ROM raised  Estimated costs £86k to £102k  System change to include  Code change to overrun prices calculation batch job in Gemini  Including indicative overrun price screen  Testing of NTS Entry Capacity invoice processes and impacted charges, including regression testing  Initial data setup for any new parameters  Estimated duration  Delivery, detailed design and development, testing and post implementation support will take 15 weeks to 21 weeks  Timescale  Implementation to consider existing programme of Gemini changes  Planning to be determined