(3)The distribution of the capital cost of water-supply, sanitary and electrical installations between the residential and non-residential portions of a building should be made on the basis of the actual cost of the relative fittings installed in each of the residential and non-residential portions of the building, anything common being divided in proportion to the capital cost of the installation in those portions. The provision of this note applies to buildings fitted with such installations after January 1, 1934.
