January 2012 Capital Investment - National Grid

Exhibit ___ (EIOP-19)Page 173 of 684NIAGARA MOHAWK POWER CORPORATIONSummary of Bill Impact Associated with FY13 - FY17 T & D Capex OnlyFor Fiscal Years 2014, 2015 & 2016($000's)Exhibit 4FY 2014 FY 2015 FY 2016Depreciation Expense 7,646 15,737 24,395Rate Base:Net Utility Plant 517,173 998,770 1,505,051Accumulated Deferred Taxes -75,922 -126,671 -184,092Total Rate Base 441,250 872,099 1,320,959ROR 9.45% 9.45% 9.45%Return on Rate Base 41,710 82,437 124,867Total Revenue Requirement Impact of FY14 - FY16 Capex Only 49,356 98,175 149,262Rate Base Impact of Depreciation on 12/31/11 Embedded Plant -76,079 -228,238 -380,397ROR 9.45% 9.45% 9.45%Total Revenue Requirement Impact of 12/31/11 Embedded Plant -7,192 -21,575 -35,958Total Revenue Requirement Impact of Capex less impact of Embedded Plant $42,165 $76,600 $113,304Allocation of Revenue Requirement to SC1 Residential Customers 25,390 46,125 68,226SC1 Residential Customers Cumulative Bill Impact per kWh $0.00236 $0.00429 $0.00635Assumptions:1) FY13 - FY17 capex per the 1/31/2012 CIP filing (Transmission, Distribution & Sub-Transmission only)2) NYS PSC Staff's Depreciation Rates per 1/24/11 Commission Order - Case 10-E-00503) ROR based on 9.3% ROE per 1/24/11 Commission Order - Case 10-E-00504) Embedded historic plant generates depreciation expense that will reduce rate base (increase todepreciation reserve). Reduced the revenue requirement to include the inherent reduction to ratebasefrom depreciating embedded plant determined as follows:December 31, 2011 Electric Depreciable Plant 6,938,712Composite Electric Depreciation Rate 2.19%Total Annual Electric Depreciation based on embedded plant 152,159Ratebase impact determined by using a half year average of annual depreciation per year5) Allocated revenue requirement to SC1 customers based on 2011 T&D Revenue at Proposed Rates perExhibit (RCDM-5), Schedule 1, Sheet 4, Column (F) (based on 1/24/11 Commission Order - Case 10-E-0050)6) SC1 bill impact utilized SC1 kWh based on 2011 T&D Revenue at Proposed Rates per Exhibit (RCDM-5),Schedule 1, Sheet 4, Column (B) (based on 1/24/11 Commission Order - Case 10-E-0050)VII - 18174