Equipment For Voltage Measurements

(1) Standards Each utility shall have at least one (1) indicating voltmeter with a stated accuracy within one quarter percent (0.25%) of full scale. This instrument must be maintained within its stated accuracy. (2) Working Instruments (a) Each utility shall have at least two (2) indicating voltmeters with a stated accuracy within one percent (1.0%) of full scale. (b) Each utility must have at least two (2) portable recording voltmeters with a stated accuracy within one and one half percent (1.5%) of full scale. (3) Standards must be checked periodically (see Rule 1220-04-04-.39(2)) at the National Institute of Standards and Technology (NIST), or at a laboratory acceptable to the Commission. (4) Working instruments be checked periodically (see Rule 1220-04-04-.39(2)) by comparison with a standard in the utility’s meter shop. (5) Extreme care must be exercised in the handling of standards and instruments to assure that their accuracy is not disturbed. (6) Each standard shall be accompanied at all times by a certificate or 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.