No railroad corporation whose railroad is operated primarily by electric energy, street railroad corporation, gas corporation, electrical corporation, telegraph corporation, telephone corporation, water corporation, or sewer system corporation shall begin the construction of a street railroad, or of a line, plant, or system, or of any extension thereof, without having first obtained from the commission a certificate that the present or future public convenience and necessity require or will require such construction.
This article shall not be construed to require any such corporation to secure such certificate for
an extension within any city or city and county within which it has theretofore lawfully commenced operations, or for an extension into territory either within or without a city or city and county contiguous to its street railroad, or line, plant, or system, and not theretofore served by a public utility of like character, or for an extension within or to territory already served by it, necessary in the ordinary course of its business. If any public utility, in constructing or extending its line, plant, or system, interferes or is about to interfere with the operation of the line, plant, or system of any other public utility or of the water system of a public agency, already constructed, the commission, on complaint of the public utility or public agency claiming to be injuriously affected, may, after hearing, make such order and prescribe such terms and conditions for the location of the lines, plants, or systems affected as to it may seem just and reasonable.