(a)  Each utility shall maintain or designate a meter shop for the purpose of inspecting, testing and repairing meters. The shop shall be open for inspection by authorized representatives of the Commission or the Public Staff at all reasonable times, and the facilities and equipment, as well as the methods of measurements and testing employed, shall be subject to the approval of the Commission.

(b)  The area within the meter shop used for the testing of meters shall be designed so that the meters and meter testing equipment are protected from drafts and excessive changes of temperature.

(1)           The calorimetric equipment shall be installed in a suitably located testing station acceptable to the  Commission and subject to inspection by the Commission Staff or the Public Staff.

(c)  The meters to be tested shall be stored in such manner that the temperature of the meters is substantially the same as the temperature of the prover.

(d)  Working Standards. - Each utility shall own and maintain, or have access to, at least one 5 cubic‑foot bell prover of an approved type, and all other equipment necessary to test meters, which shall be installed in the meter room.

(1)           Means shall be provided to maintain the temperature of the liquid in the meter prover at substantially the same level as the ambient temperature in the prover room.

(2)           The meter prover shall be maintained in good condition and correct adjustment so that it shall be capable of determining the accuracy of any service meter to within one‑half of one percent.

(e)  Each utility having meters which are too large for testing on a 5‑cubic‑foot bell prover shall use a properly calibrated test meter or a properly designed flow prover for testing the large meters.

(f)  Working standards must be checked periodically (see Rule R6‑25(5)) by comparison with a secondary standard.

(1)           Bell provers must be checked with a cubic foot bottle which has been calibrated by the National Bureau of Standards.

(2)           Rotary displacement test meters must be checked with a bell prover of adequate capacity which has been calibrated by representatives of the National Bureau of Standards.

(g)  Extreme care must be exercised in the use and handling of standards to assure  that their accuracy is not disturbed.

(h)  Each standard shall be accompanied at all times by a certificate of calibration card, duly signed and dated, on which are recorded the corrections required to compensate for errors found at the customary test points at the time of the last previous test.

(i)  Each utility must have properly calibrated orifices, as may be necessary, to achieve the rates of flow required to test the meters on its system.

(NCUC Docket No. M‑100, Sub 75, 10/27/77.)