The provisions of this act¹ shall not be applicable to municipal corporations, or beneficial trusts thereof, owning or operating electric lines or generating facilities, or the financing of a rural electric cooperative or association; and nothing in this act shall prohibit or shall ever be construed to prohibit any municipal corporation, or beneficial trusts thereof, owning or operating electric lines, from furnishing electric service to any territory thereafter annexed to and incorporated into the corporate limits of said municipal corporation, or from acquiring the electric distribution facilities of any association or cooperative corporation as now provided in Title 18, Section 437.2. Provided further that it shall not be necessary for any such municipal corporation, or beneficial trusts thereof, to secure the prior order, consent or authorization of the Commission to proceed under said Title 18, Section 437.2, but after the acquisition of any such electric distribution facilities of any association or cooperative corporation, the Commission shall be notified by such municipal corporation as to the description of the territory annexed and incorporated into the corporate limits in order that the Commission may adjust its required maps.