(1) The standards of product and service for each public utility providing electric service subject to the jurisdiction of the commission shall, whether established by ordered tariff provision or administrative rule, allow for a nominal voltage and permissible range of variation as specified in American National Standards Institute (ANSI) C84.1 2020. A copy of ANSI C84.1 may be obtained from the American National Standards Institute, Operations, 25 West 43rd Street, 4th Floor, New York, New York 10036, or may be reviewed at the Public Service Commission Offices, 1701 Prospect Avenue, Helena, Montana 59620-2601.

(2) This rule shall not apply:

(a) to transmission systems not used to directly serve customers;

(b) where customers specifically request a voltage other than standard nominal system voltages as specified in ANSI C84.1; or

(c) in instances where voltage is in excess of 34,500 volts.