January 2012 Capital Investment - National Grid

Exhibit ___ (EIOP-19)Page 71 of 684Overhead LineVarious projects are in place to refurbish or replace sub-transmission overhead assets toensure the system continues to perform in a safe and reliable manner. This includespole replacement in addition to the work generated via the Inspection and Maintenanceprogram discussed in the Statutory or Regulatory spending rationale.Drivers:Although spending is categorized by spending rationale, all drivers are considered indetermining the optimum project solution. Reliability and condition are the main driversfor these projects. Historically, the number of reliability events that are initiated on thesub-transmission system is low; however these events can result in a significant numberof customers being interrupted where the lines are radial.Physical condition of the sub-transmission system is being assessed through theInspection and Maintenance program, helicopter surveys and by local engineeringreviews and ‘walk downs’.Customer Benefits:Refurbishment and replacement of sub-transmission system components can have asignificant impact on regional CAIDI/SAIFI and Customer Minutes Interrupted (CMI)since they typically supply distribution stations.2011 to 2012 Variance:The projected investment is shown in the table below. Existing identified work under thisprogram will be continued. This program will be phased out and transitioned to theInspection and Maintenance program.Table III-10Overhead LineProgram Variance ($millions)CIP FY12 FY13 FY14 FY15 FY16 FY17 Total2011 16.4 9.5 5.3 - - - 31.22012 - 7.7 9.5 0.1 - - 17.3III-13 1372