Exhibit 31.1
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          Sarbanes - Oxley Section 302(a) Certification
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I, Thomas J. May, certify that:

1.   I have reviewed this quarterly report on Form 10-Q of
     NSTAR;

2.   Based on my knowledge, this quarterly report does not
     contain any untrue statement of a material fact or omit to
     state a material fact necessary to make the statements
     made, in light of the circumstances under which such
     statements were made, not misleading with respect to the
     period covered by this quarterly report;

3.   Based on my knowledge, the financial statements, and other
     financial information included in this quarterly report,
     fairly present in all material respects the financial
     condition, results of operations and cash flows of NSTAR as
     of, and for, the periods presented in this quarterly
     report;

4.   NSTAR's other certifying officer and I are responsible for
     establishing and maintaining disclosure controls and
     procedures (as defined in Exchange Act Rules 13a-15 and 15d-
     15(e)) for NSTAR and we have:

     a)    designed such disclosure controls and procedures, or
           caused such disclosure controls and procedures to be
           designed under our supervision, to ensure that
           material information relating to NSTAR, including its
           consolidated subsidiaries, is made known to us by
           others within those entities, particularly during the
           period in which this quarterly report is being
           prepared;

     b)    evaluated the effectiveness of NSTAR's disclosure
           controls and procedures and presented in this
           quarterly report our conclusions about the
           effectiveness of the disclosure controls and
           procedures, as of the end of the period covered by
           this quarterly report, based on such evaluation; and

     c)    disclosed in this quarterly report any change in
           NSTAR's internal control over financial reporting
           that occurred during the most recent fiscal quarter
           that has materially affected, or is reasonably likely
           to materially affect, NSTAR's internal control over
           financial reporting.

5.   NSTAR's other certifying officer and I have disclosed,
     based on our most recent evaluation of internal control
     over financial reporting, to NSTAR's auditors and the audit
     committee of NSTAR's board of trustees:

     a)    all significant deficiencies and material weaknesses
           in the design or operation of internal control over
           financial reporting which are reasonably likely to
           adversely affect NSTAR's ability to record, process,
           summarize and report financial information; and

     b)    any fraud, whether or not material, that involves
           management or other employees who have a significant
           role in NSTAR's internal control over financial
           reporting.


Date:  August 8, 2003       By: /s/ THOMAS J. MAY
                                Thomas J. May
                                Chairman, President and
                                Chief Executive Officer

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