Each city operating under the council form of government in which council members are elected at large constitutes an election district or voting precinct, and in all other cities each ward constitutes an election district or voting precinct. Whenever the number of electors in any two or more contiguous wards does not exceed one hundred as determined by the number of votes cast at the last city election, the council, by ordinance, may consolidate those two or more wards into one precinct for voting purposes. In any city containing less than four hundred electors as determined by the number of votes cast at the last city election, the council, by ordinance, may consolidate all the wards of the city into one precinct for voting purposes. An ordinance dividing or consolidating wards must be passed and takes effect before the time of giving notice of the election. Wards and precincts established under this section constitute election districts for all state, county, and city elections. In city elections, separate ballot boxes and pollbooks must be provided and kept for each precinct. The terms “wards”, “precincts”, and “election districts” have the same meaning except where two or more wards are consolidated into one precinct for voting purposes or where one ward is divided into more than one precinct for voting purposes. This section does not prohibit the use of one building as the election polling place for more than one ward or the installation of voting systems from separate wards in one building.