Normal working hours must not exceed eight hours a day,or as agreed by an employer and an employee,but not exceeding 48hours a week.However ,there are also special cases.e.g.work exceeding seven hours a day and 42 hours a week is not permitted where the heath and safety of an employee is at risk such as in underground work,underwater work,in a cave or tunnel,work in a confined place,work involving radioactivity,metal welding work,hazardous substance transoprt work,hazardous chemical production work etc.