068301-0006-1001 6-Active.1 1878547.4 FIRST SUPPLEMENTAL INDENTURE among THE NARRAGANSETT ELECTRIC COMPANY as Issuer, and THE BANK OF NEW YORK MELLON, as Trustee and Paying Agent March 22, 2010 $250,000,000 4.534% SENIOR NOTES DUE 2020 EXECUTION COPY