which the standard will be used, such meter shall be tested, adjusted and certified in the laboratory or by the Commission. Each portable watt-hour meter (rotating standards) shall at all times be accompanied by a certificate or calibration card, signed by the proper authority, giving the date when it was last certified and adjusted. Records of certification and calibration shall be kept on file in the offices of the utility for a period of at least one (1) year.
39 Miss. Code. R. 3-2-17