Section 2N:
Public utility service
(i) any railway service or any transport service for the carriage of passengers or goods by air
(i-a) any service in, or in connection with the working of, any major port or dock
(ii) any section of an industrial establishment, on the working of which the safety of the establishment or the workmen employed therein depends
(iii) any postal, telegraph or telephone service
(iv) any industry which supplies power, light or water to the public
(v) any system of public conservancy or sanitation
(vi) any industry specified in the First Schedule which the appropriate Government may, if satisfied that public emergency or public interest so requires, by notification in the Official Gazette, declare to be a public utility service for the purposes of this Act, for such period as may be specified in the notification
Provided that the period so specified shall not, in the first instance, exceed six months but may, by a like notification, be extended from time to time, by any period not exceeding six months, at any one time, if in the opinion of the appropriate Government, public emergency or public interest requires such extension