You have tagged the Government Polytechnic Bhubaneswar & Mahatma Gandhi mission Jawahar Lal Nehru Engineering College in your question. So I am answering about that. The admission to the diploma in Electrical Engineering is merit based. The eligibility criteria for pursuing diploma in Electrical Engineering is to complete 10th class board examination with at least 35% marks in the aggregate. You must have a studied English, Mathematics and Science subjects in your 10th class board examination. There is no upper age limit for applying for diploma in electrical engineering.
Admission to the Mahatma Gandhi mission Jawaharlal Nehru Engineering College electrical engineering is done on the basis of either MHT CET or PERA CET or MGMU CET.
The candidates who have passed class 10th or 12th can apply for admission to Diploma in Engineering .
But, as you've already completed your +2, it will be my advice to apply directly for a B. Tech instead of a Diploma.
Anyhow, after completing a degree in Diploma, you can go for B. Tech which will collectively take 6 years to complete your engineering (3 years diploma + 3 years B. Tech)
Hope this was helpful.