R8-12     METER ACCURACY

(a)  No watt hour meter that registers on "no load" as defined by ANSI C12.1 (voltage circuits energized and zero current), shall be placed in service or allowed to remain in service.

(b)  No watt hour meter shall be placed in service that is in any way defective or has incorrect constants, nor shall any watt hour meter be maintained in service that does not meet the following performance requirements: Average percent registration not less than 98% or more than 102%.

(c)  All meters shall be accuracy tested by the manufacturer. Test results shall be provided to the utility and stored by the utility for the life of the meter and at least three years after the retirement of the meter.

(d)  Acceptance testing shall be performed on a statistically valid sample of each shipment of new meters. The statistical sampling plan used shall conform to the accepted principles of statistical sampling as set forth in ANSI Z1.4 – Sampling Procedures and Tables for Inspection by Attributes, ANSI Z1.9 – Sampling Procedures and Tables for Inspection by Variables for Percent Nonconforming, or other generally accepted statistical methodology. If the total number of failures exceeds the level allowed under the sample plan, the entire shipment will be rejected and returned to the manufacturer or corrected on site.

(e)  Whenever a test made by the utility or Commission on a service watt hour meter connected in its permanent position in place of service shows an average percent registration less than 98% or more than 102%, the meter shall be replaced.

(f)  A service watt hour meter having an average percent registration not less than 98% or more than 102% may be considered as correct, and no adjustment of charges shall be entailed by such an error.

(NCUC Docket No. E-100, Sub 29, 11/29/77; NCUC Docket No. E-100, Sub 153, 11/27/2019.)