(a)  Meter Test. - Each utility shall, unless specifically excused by the Commission, provide for and have available such meter‑testing instruments and other equipment and facilities as may be necessary to make the tests required by these rules or other orders of the Commission. Such equipment and facilities shall be satisfactory to and approved by the Commission and shall be available at all reasonable times for the inspection and use of any authorized representative of the Commission.

(b)  Certification of Instruments and Equipment. - All testing instruments and other equipment shall at all times be accompanied by a certificate signed by a proper authority giving the date when it was last certified and adjusted, and certificates, when superseded, shall be kept on file in the office of the utility.