Section 14. Gas and electric companies shall issue only such amount of stock and bonds, and of coupon notes and other evidences of indebtedness payable at periods of more than one year after the date thereof, as the department may from time to time vote is reasonably necessary for the purpose for which such issue of stock, bonds, coupon notes or other evidences of indebtedness has been authorized. The department may take into consideration any resources of the companies available or which might have been available for said purpose. The department shall render a decision upon an application for such issue within thirty days after the final hearing thereon. The decision shall be in writing, shall assign the reasons therefor, shall, if approving such issue, specify the respective amounts of stock, bonds, coupon notes or other evidences of indebtedness which are approved to be issued for the respective purposes to which the proceeds thereof are to be applied, and shall, within seven days after it has been rendered, be filed in the office of the department. A certificate of the vote of the department shall, within three days after such decision has been rendered and before the stock, bonds, coupon notes or other evidences of indebtedness are issued, be filed in the office of the state secretary, and a duplicate thereof delivered to the corporation, which shall enter the same upon its records. A company subject to this section shall not apply the proceeds of such stock, bonds, coupon notes or other evidences of indebtedness to any purpose not specified in such certificate. No application for the approval of an issue of stock shall be made unless authorized by vote of the directors passed not more than four months prior to such application.