All portable indicating electrical instruments used for determining quality of service to customers or for billing purposes, such as voltmeters, ammeters, and wattmeters, shall be checked against suitable secondary reference standards at least once in each twelve months. If the portable indicating instrument is found appreciably in error at zero, or in error by more than two percent of indication at full scale deflection, it shall be adjusted to indicate correctly.
N.D. Admin Code 69-09-02-20
General Authority: NDCC 49-02-11
Law Implemented: NDCC 49-02-11