Manufacturing of electrical equipment or electronic items is not a scheduled industry under the MMW Rules 1948. Therefore, your manufacturing unit will fall under the residuary category.
What I believe is that you are in manufacturing and not in engineering, i.e., not in designing, building, or maintaining any structure, machine, device, etc., by applying scientific technology.
If you are in the Electronic Exports Processing Zone, then you are in the scheduled industry of SEEPZ.
Regards