According to the Factories Act, the provisions are laid down under sections 51, 54, 55, and 56.
Although the maximum working hours are 9 hours, they can be spread over to 12 hours per day. The 12-hour shift is for people who are said to be working under the "Compressed Shift." Shift rotation is managed accordingly, scheduling the number of working days and allowing the employees corresponding take-offs is called a compressed shift.
Provisions of the Factories Act
Under the provisions of the Factories Act, you can refer to the following:
Section 51. WEEKLY HOURS
No adult worker shall be required or allowed to work in a factory for more than forty-eight hours in any week.
Section 54. DAILY HOURS
Subject to the provisions of section 51, no adult worker shall be required or allowed to work in a factory for more than nine hours in any day. Provided that, subject to the previous approval of the Chief Inspector, the daily maximum hours specified in this section may be exceeded to facilitate the change of shifts.
Section 55. INTERVALS FOR REST
(1) The periods of work for adult workers in a factory each day shall be fixed so that no period exceeds five hours and no worker shall work for more than five hours before having an interval for rest of at least half an hour.
(2) The State Government or, subject to the control of the State Government, the Chief Inspector, may exempt any factory from the provisions of subsection (1) by written order for specified reasons, ensuring that the total number of hours worked by a worker without an interval does not exceed six.
Section 56. SPREADOVER
The periods of work for an adult worker in a factory shall be arranged so that, including intervals for rest under section 55, they shall not spread over more than ten and a half hours in any day. The Chief Inspector may, for specified reasons in writing, increase the spreadover up to twelve hours.