Conn. Gen. Stat. § 16-229: Excavation in highway.

Any public service company incorporated under the provisions of the statutes or by special act for the purpose of transmitting or distributing gas, water or electricity or for telephone purposes, desiring to open or make any excavation in a portion of any public highway for the carrying out of any purpose for which it may be organized other than the placing or replacing of a pole or of a curb box, shall, if required by the authority having jurisdiction over the maintenance of such highway, make application to such authority, which may, in writing, grant a permit for such opening or excavation upon such terms and conditions as to the manner in which such work shall be carried on as may be reasonable.