(1)    Except as provided in subs. (2) and (3), the common council or governing body of every city having a paid fire department shall provide for, and the chief engineer of the department shall assign to, each fire fighter in the service of the city full rest days as follows:

      (a)    In 1st class cities, one full rest day of 24 consecutive hours during each 72 hours.

      (b)    In 2nd and 3rd class cities, one full rest day of 24 consecutive hours during each 96 hours.

      (c)    In 4th class cities, one full rest day of 24 consecutive hours during each 168 hours.

   (2)   The rest day requirements under sub. (1) do not apply in cases of positive necessity by some sudden and serious fire, accident or other peril, which, in the judgment of the chief engineer, or other officers in charge, demands that a day of rest not be given at that time, but arrangements shall be made so that each full rest day may be had at such time or times as will not impair the efficiency of the department.

   (3)   The provisions of this section shall not apply to cities having the 2 platoon or double shift.