220 ILCS 30/7
Except as otherwise provided in this Act, until the respective service areas of the affected electric suppliers have been determined as provided in Section 6, no electric supplier may make an extension of existing lines or construct new lines for the purpose of furnishing service to a customer or premises which it is not entitled to serve under Section 5, or furnish service to any customer or premises which such supplier is not entitled to serve under Section 5, unless in any such case such electric supplier gives written notice to the electric supplier or suppliers which may be adversely affected by the proposed construction, extension or service. Any electric supplier which claims that it should be permitted to serve any customer or premises which could be served by such proposed construction, extension or furnishing of service may within 20 days after receipt of such notice or, if no notice is received, not later than 18 months after the completion of such proposed construction, extension or the commencement of service, file its complaint with the Commission which shall proceed to determine the issue as provided in Section 8.
The electric supplier giving such notice may, however, commence such construction, extension or service, subject to the subsequent final determination of the Commission as to which supplier should be permitted to furnish such service.
This Section does not apply to and no notice need be given under this Section by (1) a public utility constructing new lines, extending existing lines or furnishing service in any county in which there are no existing lines of an electric cooperative and which is not adjacent to any county in which there are existing lines of an electric cooperative or constructing new lines, extending existing lines or furnishing service more than 5 miles away from an existing line of an electric cooperative; (2) a generation and transmission electric cooperative making a construction or extension of lines solely to serve its member distribution electric cooperatives which are not incorporated municipalities; (3) any electric supplier constructing new lines or extending existing lines to furnish service exclusively to its own property and for its own use; and (4) any electric supplier making, for the purpose of furnishing service to a customer, an extension of 300 feet or less of line having a voltage of 600 volts or less which does not make the service of that supplier any nearer to the existing lines of another supplier than at the effective date of this Act.
220 ILCS 30/7