Ohio Rev. Code § 4906.05
No certificate is required for a major utility facility on which construction had already commenced on October 23, 1972, or within two years thereafter. This section does not exempt such a facility from any other requirements of state and local laws and regulations.
No certificate is required for any major utility facility already in operation on October 23, 1972, and the facility shall not be exempt from any applicable state or local laws or regulations. A certificate is required for any substantial addition to a facility already in operation. "Substantial addition" shall be defined by the power siting board.
Any electric generating plant and associated facilities, electric transmission line and associated facilities, or gas pipeline and associated facilities which is not a major utility facility is not exempt from state or local laws or regulations.
R.C. § 4906.05