Dear aspirant , 

The tag of  NIT will just  help you  in getting a good placement , if you don't have any knowledge of that particular field you will end up getting a low salary job and plus you won't even like doing that job and you will be ultimately unhappy due to it . So do the job which you like and pursue your interest which will ultimately make you  successfull in that field . The tag of NIT will be just an entry point .

If you want to come back and join an It company why are you wasting your valuable money and time for doing mtech in electrical , instead of it do mtech in information technology or computer science, you can also enhance your knowledge in software field .
Doing mtech in electrical and getting a job in information technology will ultimately get you a low salary job . The tag of Nit will just be for placements and nothing else.

Hope it will help you .