Iowa Code § 411.16: Hours of service.

Fire fighters employed in the fire department of cities of ten thousand population or more, or under civil service, shall not be required to remain on duty for periods of time which will aggregate in each month more than an average of fifty-six hours per week and no single period of time, or shift, shall exceed twenty-four hours in length, provided that in cases of serious emergencies such fire fighters may be required to remain on duty until such emergency has passed, when so ordered by the chief of the department or person acting in the chief’s place. Fire fighters called back to duty under this provision shall be duly compensated in accordance with their regular hourly wage.