Can I sit for IES exam, if I am pursuing Btech in power engg?

Sure you can. Any main BE course qualifies you to take up IES.

U must have degree if u want to sit for IES examination. As u are pursuing the degree u are not eligible for appearing in IES exam. U can follow the link for the detailed information :- http://gateforum.com/ies/ies-eligibility/

Hi, any B.E or B.Tech degree (in any branch) is eligible to write IES examinations conducted by UPSC. Visit following page to read more about other eligibility criteria for IES, https://www.facebook.com/permalink.php?id=325435624236565&story_fbid=597646913682100 Wish you all the very best.

U need to have a degree to write civils exam