Ind. Admin. Code tit. 170, r. 4-1-20 – Standard nominal service voltage; permissible voltage variation

Sec. 20. Standard Voltage and Permissible Voltage Variation. (A) Each public utility shall adopt a standard nominal service voltage, or standard nominal service voltages, as may be required by its distribution system for its entire constant voltage service, or for each of the several districts into which the systems may be divided, and shall file with the commission a statement as to the standard nominal voltages adopted. The voltage maintained at the customer's main service terminals shall be reasonably constant, as follows:

(1) For residential service, the voltage shall be within five percent (5%) plus or minus of the standard adopted, and the total variation of voltage from minimum to maximum shall not exceed six percent (6%) of the average voltage in cities and other incorporated places having a population in excess of 2,500, nor eight percent (8%) of the average voltage in all other places.
(2) A greater variation of voltage than specified above may be allowed when service is supplied directly from a transmission line, or in a limited or extended area where customers are widely scattered or the loads served do not justify close voltage regulation. In such cases the best voltage regulation should be provided that is practicable under the circumstances.

(B) Variations in voltage in excess of those specified, caused by (1) the operation of power apparatus on the customer's premises which necessarily requires large starting current, (2) the action of the elements, and (3) the infrequent and unavoidable fluctuations of short duration due to station operation, shall not be considered a violation of this rule.

(Indiana Utility Regulatory Commission; No. 33629: Standards of Service For Electrical Utilities Rule 18; filed Mar 10, 1976, 9:10 am: Rules and Regs. 1977, p. 354; readopted filed Jul 11, 2001, 4:30 p.m.: 24 IR 4233; readopted filed Apr 24, 2007, 8:21 a.m.: 20070509-IR-170070147RFA; readopted filed Aug 2, 2013, 2:16 p.m.: 20130828-IR-170130227RFA; readopted filed Apr 11, 2019, 9:04 a.m.: 20190508-IR-170190136RFA; readopted filed Sep 12, 2025, 11:43 a.m.: 20251001-IR-170240381RFA)