The provisions of § 237-102 shall not be applicable:
A. To private residences in which no more than two families are or can be housed. To all larger dwellings, of whatever type, however, this Part shall be fully effective and applicable.
B. When a fire box, furnace, boiler, locomotive or other fuel-consuming device is being cleaned out and a new fire is being built therein, in which event a smoke of a density greater than that described as No. 2 of the Ringelmann Chart shall be permitted for a period of not to exceed six minutes in any single period of 60 minutes.