Step 1: The Factories Act of India caps ordinary working time at 48 hours per week.
Step 2: Over and above this, the Act permits overtime of about 2 hours per working day. Across a working week this adds roughly 12 more hours.
Step 3: Adding the base 48 hours to the permitted overtime gives an upper ceiling of about 60 hours per week including overtime.
So the maximum, inclusive of overtime, is 60 hours.
Ref: Park Textbook of Preventive and Social Medicine, 24e, p.852.