Electric Company Nantucket Electric Company each d/b/a National Grid D.P.U. 18-150 Attachment AG-1-98 Supplement Page 1 of 3

NATIONAL GRID PLC

NATIONAL GRID (US) HOLDINGS LTD

- NATGRIDTW1 LTD NATIONAL GRID (US) INVESTMENTS 4 LTD - NATIONAL GRID TWENTY-FIVE LTD

NATIONAL GRID TWELVE LTD NATIONAL GRID (US) PARTNER 1 LTD

NATIONAL GRID (US) INVESTMENTS 2 LTD NATIONAL GRID NORTH AMERICA INC.

NATIONAL NGV EMERALD NATGRID ONE LTD GRID US LLC HOLDINGS, LLC NATIONAL GRID USA NATIONAL GRID TEN NATIONAL GRID NATIONAL GRID NGT TWO LTD INSURANCE USA LTD TWENTY THREE LTD NGV EMERALD NATIONAL GRID ACQUISITION CO.,LLC US 6 LLC

GRIDAMERICA HOLDINGS INC.

90% 50% NEW ENGLAND POWER - EUA ENERGY INVESTMENT CORP. WAYFINDER GROUP INC. NIAGARA MOHAWK COMPANY - MASSACHUSETTS ELECTRIC COMPANY VERMONT SWAN LAKE NORTH HOLDINGS INC. - METROWEST REALTY LLC 21.6% GREEN LINE HOLDINGS LLC - NANTUCKET ELECTRIC COMPANY DEVCO, LLC 4 - NATIONAL GRID TRANSMISSION GREENERU, INC. 100% NATIONAL GRID CONNECT INC. 32% - CONNECTICUT YANKEE SERVICES CORPORATION ATOMIC POWER COMPANY SWAN LAKE - NATIONAL GRID USA SERVICE CLEAN LINE ENERGY 18.42% (19.5%) NORTH COMPANY INC See PARTNERS LLC - MAINE YANKEE ATOMIC NATIONAL GRID GREEN HYDRO, LLC - NEES ENERGY INC. separate ENBALA HOLDINGS INC. POWER COMPANY (24%) HOMES INC. 50% - NEW ENGLAND ELECTRIC chart on - YANKEE ATOMIC TRANSMISSION CORPORATION GOLDENDALE 50% page 2 NORTHEAST ELECTRIC COMPANY (34.5%) - NEW ENGLAND ENERGY ENERGY - NEW ENGLAND HYDRO- RENEWABLE NIAGARA OPINAC NORTH INCORPORATED SUNRUN NEPTUNE STORAGE LINK LLC MOHAWK POWER AMERICA INC. TRANSMISSION CORP. - NEWPORT AMERICA CORPORATION LLC. (3.27%) INVESTOR 2016, LLC. CORPORATION - THE NARRAGANSETT ELECTRIC 16% - NEW ENGLAND HYDRO- COMPANY TRANSMISSION ELECTRIC 50.434% GRANITE FFP PROJECT 101, - VALLEY APPLIANCE AND 50% STATE NM PROPERTIES E VIONYX ,INC. COMPANY INC. (3.27%) MERCHANDISING COMPANY NEW ENGLAND HYDRO- LLC. INC. TRANSMISSION POWER LINK LLC CORPORATION NIAGARA MOHAWK - LANDWEST, INC. LAND MANAGEMENT & ENERGY INC. 50.434% - UPPER HUDSON DEVELOPMENT, INC. NEW ENGLAND HYDRO- 50% DEVELOPMENT INC. 26% TRANSMISSION ELECTRIC COMPANY INC. DIRECT GLOBAL PORT OF THE ISLANDS POWER, INC. NORTH, LLC NEW ENGLAND HYDRO FINANCE COMPANY INC. Massachusetts Electric Company Nantucket Electric Company each d/b/a National Grid D.P.U. 18-150 Attachment AG-1-98 Supplement Page 2 of 3

NATIONAL GRID USA

5%

NATIONAL GRID - KEYSPAN GAS EAST CORPORATION UNIT 40 SUBLESSOR, KEYSPAN ENERGY NGNE LLC 99% GENERATION LLC - NATIONAL GRID ELECTRIC SERVICES LLC LLC CORPORATION - NATIONAL GRID ENERGY TRADING SERVICES LLC - NATIONAL GRID ENGINEERING & SURVEYING INC. 1% GRID NY LLC NATIONAL GRID NE HOLDINGS 2 LLC 28.3% - BOSTON GAS COMPANY TRANSCO LLC - COLONIAL GAS COMPANY - TRANSGAS INC. - MYSTIC STEAMSHIP CORPORATION - PHILADEPLPHIA COKE CO., INC NATIONAL GRID NATIONAL GRID NATIONAL GRID PORT - KHB VENTURE , LLC (33.33%) GENERATION GLENWOOD ENERGY JEFFERSON ENERGY VENTURES LLC CENTER, LLC CENTER LLC

- ISLAND PARK LI ENERGY STORAGE ENERGY CENTER, SYSTEM, LLC (50%) LLC (50%) THE NATIONAL GRID KEYSPAN MHK, INC. NATIONAL GRID SERVICES INC. NATIONAL GRID PARTNERS INC. -LI SOLAR UNION GAS COMPANY DEVELOPMENT GENERATION, LLC 50% 50% HOLDINGS CORP. 18.2% (50%) EAST MONTAUK See separate - CLEAN ENERGY MYHOMEKEY.COM HAMPTON ENERGY chart on GENERATION, LLC ENERGY STORAGE page 3 (50%) STORAGE CENTER, CENTER, LLC LLC KSI CONTRACTING KSI ELECTRICAL, KSI MECHANICAL, NATIONAL GRID LLC LLC LLC ENERGY SERVICES LLC 9.68% 5.29% NORTH EAST NYSEARCH NYSEARCH TRANSMISSION CO., INC. RMLD, LLC ROBOTICS, LLC KEYSPAN ENERGY NATIONAL GRID ENERGY KEYSPAN PLUMBING SERVICES INC. MANAGEMENT LLC SOLUTIONS, INC.

METRO ENERGY L.L.C

NATIONAL GRID BROKEN NATIONAL GRID KEYSPAN NATIONAL KEYSPAN NATIONAL GRID NATIONAL GRID NATIONAL GRID NATIONAL GRID ALGONQUIN LLC BRIDGE NORTH EAST INTERNATIONAL GRID IGTS 77% MIDSTREAM INC. MILLENIUM LLC ISLANDER EAST LNG GP LLC LNG LP LLC CORP. VENTURES INC. CORPORATION CORP. 23% PIPELINE LCC 20% 0.5% 99.5% 26.25% 50% ALGONQUIN GAS KEYSPAN CI TRANSMISSION, MIDSTREAM LLC 5 LIMITED MILLENIUM ISLANDER EAST NATIONAL GRID LNG LLC PIPELINE PIPELINE COMPANY, LLC COMPANY, LLC

KEYSPAN ENERGY DEVELOPMENT Co. Massachusetts Electric Company Nantucket Electric Company each d/b/a National Grid D.P.U. 18-150 Attachment AG-1-98 Supplement Page 3 of 3

NATIONAL GRID PARTNERS INC

9.42% 7.59% 4.9% 4.7% 4.9% .9% 74% 4.5% 1.89% 6.9%

ENERGY IMPACT FUND APORETO, INC. AUTOGRID CARBON CLIMACELL, DRAGOS, PASSION CAPITAL GC SPARKCOGNITION, JVP VIII, SITETRACKER, INC. LP SYSTEMS, INC. LIGHTHOUSE, INC. INC. INC. LP INC. L.P.