Section 419(1) in Kolkata Municipal Corporation Act, 1980
(1)No person shall, without the previous permission in writing of the Municipal Commissioner or otherwise than in conformity with the conditions, if any, of such permission, establish in any premises, or materially alter, enlarge or extend, any factory, workshop or trade premises in which it is intended to employ steam, electricity, water or other mechanical power :Provided that no such permission shall be granted in contravention of the provisions of section 425.
