Dear Kiran Kumar,
Minimum Wage Rates are always according to category of workman i.e. Highly Skilled, Skilled, Semi-Skilled and Un-skilled, not like as you have asked. If we go as per Factories Act'1948, everyone is a worker whether he/she is Off role (Contractual) or On role employee.
Second thing, Minimum Wages are also Zone wise. You have to find out that in which Zone your company comes under (Zone-1 or Zone-2).
Regards
Mohit Kumar
Team-HR
Essar Power