TITLE 83: PUBLIC UTILITIES
CHAPTER I: ILLINOIS COMMERCE COMMISSION
SUBCHAPTER c: ELECTRIC UTILITIES
PART 410 STANDARDS OF SERVICE FOR ELECTRIC UTILITIES AND ALTERNATIVE RETAIL ELECTRIC SUPPLIERS
SECTION 410.300 VOLTAGE REGULATION
Section 410.300 Voltage Regulation
a) Standard voltage. Each entity supplying electrical energy for general use shall adopt a standard service voltage of 120 volts (when measured phase to neutral) and shall maintain the service voltage within the allowable variations from that value at all times.
b) Allowable voltage variations. For service rendered at the standard service voltage, voltage variations as measured at any customer's point of delivery shall not exceed a maximum of 127 volts nor fall below a minimum of 113 volts for periods longer than two minutes in each instance. For service rendered at voltages other than the standard voltage value, voltage variations as measured at any customer's point of delivery shall not exceed 10% above or below the service voltage for a longer period than two minutes in each instance.
c) Variations of voltage in excess of those specified above shall not be considered a violation of this Section if caused:
1) by operations of a retail customer in violation of an agreement with or the rules of the entity;
2) by the operation of apparatus on a retail customer's premises that results in large inrush currents;
3) by infrequent and unavoidable fluctuations of short duration due to system operation; or
4) by acts of nature or other situations beyond the entity's control.