Rationalisation of Maintenance Planning Dates & Timescales

1. Rationalisation of Maintenance Planning Dates & Timescales Ritchard Hewitt – 2nd October 2008

2. Background • National Grid must publish two annual Maintenance Programmes: • The April Maintenance Programme covers maintenance planned for the upcoming summer period (Apr - Oct) • The October Maintenance Programme updates the April plan for maintenance that has overrun into the winter • The dates and timescales for publication are set out in two parts of the UNC: • TPD Section L – Maintenance and Operational Planning • OAD Section G – Maintenance • There are inconsistencies in the requirements of these two sections of Code

3. Comparison of Existing UNC Requirements • Publication Dates • Time Period Covered by Programme

4. Additional Concerns • The publication of a summer maintenance plan covering 24 months is inconsistent with available data as no specific maintenance dates are agreed with affected parties beyond 12 months • The purpose of the October Maintenance Programme is to document maintenance overrunning into the winter period, and hence a 24 month time period is also inconsistent • Producing a first draft of the summer plan prior to the preceding winter is of questionable value as the data on which it is based cannot include the winter performance of the system

5. Proposed Rationalisation of UNC Requirements • Publication Dates • Time Period Covered by Programme • The new dates are as per the current TPD requirements • The April Plan is reduced from 24 months, the October Plan is as per the current OAD

6. Benefits of the Proposal • Remove contradictory UNC requirements • Improve the efficiency of implementation of the UNC • Improve the efficiency of Transporters’ maintenance planning activities, and • Reduce the uncertainty as a result of these activities for Users and end consumers