Notwithstanding any other provisions of this chapter, after any part of this chapter takes effect, no municipality operating an electric plant or distribution system, whether under authorization of this chapter or any other general law or special act, shall extend its service lines into any area outside its borders where electric service is otherwise then available, except with the consent of the municipality in which such outside area is located. Such consent shall be given only after application therefor to the legislative body of the town or city in which it is sought to extend the lines. Such body shall fix a time and place for hearing on such application and post a notice thereof in the office of the clerk of the town or city, as the case may be, at least 30 days before such time fixed for hearing. At such hearing or some adjourned session thereof such legislative body shall determine whether such consent is in the public interest, and shall issue or withhold its certificate accordingly. However, such legislative body shall not act with reference to the issuance of such certificate contrary to the action, if any, of the legal voters of such municipality, taken at any annual or special meeting thereof duly warned.