How Many Hour The Employee Should Work As Per Rule

Dear HR professionals,
Please guide me on my below query.....
A Employee had work 12 hour in one day,
then as per rule how many hour will be consider for one shift and how many remaining hour for OT,
Regard
Anil gautam

Is the organisation governed by Factories Act or State shops and establishment act?
Factories act
An adult worker shall not be employed for more than 48 (forty eight) hours in a week and not more than 9 (nine) hours in a day. A compulsory rest of at least half an hour (30 minutes) between each period of work and such period of work shall not exceed five hours. Total period of work inclusive of rest interval cannot be more than 10.5 hours.
Shops and Establishment act
State act fixes the maximum number of work hours to 9 hours a day and 48 hours a week.
As far as OT is concerned if an employee works for more than 9 hours a day or48 hours a week he starts getting OT.

After completion of 9 hrs Working, OT is started. If any employees work 12 hrs in a day, Overtime calculation is OT = (12-(8+1))=3 hrs

The Employee has to work for 8 hours actually in a day.
With interval and rest period, it should not exceed 10 Hours.
(that means 30 Mts.X 2 times =1 hour and 1 hour lunch time etc+
8 hours duty period )
Employee who worked for 12 hours in a day will have to get 8 hours normal wages and for other 4 hours of work, he will have to get twice of wages. (that means in case if his wage per day is Rs.400, then he will have to get Rs.800 for 12 hours work)
Shift work means only for 8 hours actual work.

Shift work means 8 hours only.
If an employee have to work for 12 hours ( he will have to get wages for actual work ) . That means in case he works for 10 hours and take intervals for 2 hours for tea time and lunch
time ,he will have to get wages for 10 hours.
In that 10 hours work, 8 hours normal wage and for 2 hours double wage. Suppose his wages is 400 for one day of 8 hours, he will have to get Rs.600.

When you pose question, please narrate the background. Factory or establishhment, asking or allowing 12 hours working is illegal.

if they work honestly and smartly.......then minimum it can be 8hrs.
Above this it should not ..........it depends on employees' efficiency

respected seniors,
some seniors has advised OT shall be started if working is beyond 9 hour and some has advised after working 8 hour,
even in this thread some has suggest for 8 hour and some has suggest for 9 hour however this diferent advised in respect to working hour rule let me always to be confused therefore all of you are resquested to explain the exact rule weather working should be for 8 hour or 9 hour