In addition to the requirements of Article 1 (commencing with Section 1001) and any other provision of law, every electrical and every gas corporation proposing to construct or modify any electric or gas plant within the state, or line, or extension, which will in the case of an electrical plant, line, or extension add generating capacity in excess of 50 megawatts, or in the case of a gas plant, line, or extension cost in excess of fifty million dollars ($50,000,000), or proposing to construct any electric or gas plant out-of-state of which at least twenty-five percent (25%) of the costs will be borne by the corporation, shall comply with this article.