Exhibit 99.1 CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350 AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 In connection with the Annual Report of Northeast Utilities (the Company) on Form 10-K for the period ending December 31, 2002 as filed with the Securities and Exchange Commission (the Report), we, Michael G. Morris, Chairman, President and Chief Executive Officer of the Company and John H. Forsgren, Vice Chairman, Executive Vice President and Chief Financial Officer of the Company, certify, pursuant to 18 U.S.C. Sec. 1350, as adopted pursuant to Sec. 906 of the Sarbanes-Oxley Act of 2002, that: 1) The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and 2) The information contained in the Report fairly presents, in all material respects, the financial condition and result of operations of the Company. /s/ Michael G. Morris (Signature) Michael G. Morris Chairman, President and Chief Executive Officer /s/ John H. Forsgren (Signature) John H. Forsgren Vice Chairman, Executive Vice President and Chief Financial Officer March 21, 2003