All property which has been valued and assessed as residential property within a zone designated as residential and which has been so assessed for a period of 3 years or longer, and which upon the revision of a zoning ordinance becomes situate in a commercial or industrial zone, shall continue to be valued and assessed as residential property so long as the owner thereof at the time of the change in the zoning ordinance shall continue to occupy such property as his principal place of residence.

L.1977, c. 434, s. 1.