§ 115. Public letting of contracts. The commission is hereby
authorized, whenever it is of opinion that the public interest so
requires, to direct any public utility subject to the jurisdiction of
the commission to award contracts or agreements for the construction,
improvement or extension of its plant, works or system, exceeding in
amount twenty-five thousand dollars in any calendar year, to the lowest
responsible bidder, after a public offering has been made and after
advertisement and notice of such offering have been given, and the
commission may prescribe rules and regulations relative to such
advertisement, notice and public letting.