(1) The city shall not sell, exchange, lease, or in any way alienate or dispose of the property, easements, or other equipment, privileges or assets that are essential parts of any utility that it may acquire, unless and except the proposition for such purpose shall first have been submitted and approved by a majority vote of the electors voting thereon at a municipal election in the manner provided in this charter.
(2) All contracts, negotiations, licenses, grants, leases, or other forms of transfer in violation of this provision shall be void and of no effect as against the city.
(3) This section shall not, however, be interpreted to preclude the sale, exchange, or other disposal to the advantage of the city, of parts of a utility's property and assets that are not essential to continued effective utility service and the disposal of which will not prejudice municipal interests.