66 Pa.C.S. § 2107

The provisions of this chapter shall not be applicable to the rates and related terms and conditions for the interstate transmission of electricity, natural gas, liquified natural gas, substitute natural gas, liquified propane gas or naphtha which have been submitted to and approved by a Federal regulatory agency having jurisdiction thereof, except that the commission may regulate the volume of such purchases. This section shall not apply to any proceeding under section 1317 (relating to regulation of natural gas costs) or 1318 (relating to determination of just and reasonable natural gas rates).