66 Pa.C.S. § 1507

Every public utility, furnishing service upon meter or other similar measurement, shall provide, and keep in and upon the premises of such public utility, suitable and proper apparatus, to be approved from time to time and stamped or marked by the commission, for testing and proving the accuracy of meters furnished by such public utility for use; and by which apparatus every meter may be tested, upon the written request of the consumer to whom the same shall be furnished, and in the presence of the consumer, if he shall so desire. If the meter so tested shall be found to be accurate, within such commercially reasonable limits as the commission may fix for such meters, a reasonable fee, to be fixed by the commission, sufficient to cover the cost of such test, shall be paid by the consumer requiring such test; but, if not so found, then the cost thereof shall be borne by the public utility furnishing the meter.