Exhibit 31.1


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

1.   I have reviewed this quarterly report on Form 10-Q of
     Boston Edison Company (Boston Edison);

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 Boston
     Edison as of, and for, the periods presented in this
     quarterly report;

4.   Boston Edison'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 Boston Edison 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 Boston Edison,
           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 Boston Edison'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
           Boston Edison'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, Boston
           Edison's internal control over financial reporting.

5.   Boston Edison's other certifying officer and I have
     disclosed, based on our most recent evaluation of internal
     control over financial reporting, to Boston Edison'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 Boston Edison'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 Boston Edison's internal control over
           financial reporting.


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