If your salary is more than RM 1.5k but is manual workers such as labourers, machine operators and all those doing manual work, then you still covered by EA irrespective of the amount wages.
If you are not cover by EA then you need to refer back to your offer letter. The offer letter will stated the OT rate, if don't have then you need to go to your HR department.
For OT that EA cover, example calculate:-
Salary 1000 (monthly)
Normal working hour:
1000/26 = RM38.46 x 2 = RM 76.92 (excluded from basic)
1000/26 = RM38.46/8 = RM4.81 per hour x 3 = RM14.42 per hour
So, if you work OT 2 hour, RM 14.42 x 2 = RM 28.85 (excluded from basic)