Exhibit 1 COMMONWEALTH ENERGY SYSTEM LIST OF SUBSIDIARIES DECEMBER 31, 1997 Advanced Energy Systems, Inc. Cambridge Electric Light Company Canal Electric Company COM/Energy Acushnet Realty COM/Energy Cambridge Realty COM/Energy Freetown Realty COM/Energy Marketing, Inc. COM/Energy Research Park Realty COM/Energy Resources, Inc. COM/Energy Services Company COM/Energy Steam Company COM/Energy Technologies, Inc. Commonwealth Electric Company Commonwealth Gas Company Darvel Realty Trust Hopkinton LNG Corp.