Normal working hours must not exceed eight hour a day,or as greed by an employer and an employee,but not ecxeeding 48 hours a week .However ,there are also special cases ,e.g. work exceeding 7 hours a day and 42 hours a week is not permitted where the health and safety of an employee is at risk such as in underground work,under water work, in a cave or tunnel,work in a confined place,work involving radioactivity,metal welding work,hazardous substance transport work ,hazardous chemical production work etc.