The invention in a first aspect relates to an improved cast resin bushing assembly for use in a transformer wherein the busing assembly includes a bushing which includes locating means for aligning the bushing assembly within a transformer casing; wherein the bushing further includes a locking means for releasably securing the bushing assembly to a transformer casing; a bushing conductor; and a bushing flange in circumferential arrangement with the bushing. In a second aspect the invention relates to a method of securing an improved cast resin bushing assembly to a transformer casing which bushing assembly includes a bushing which includes a locating means for aligning the bushing assembly within a transformer casing; the bushing further includes a locking means for releasably securing the bushing assembly to a transformer casing; a bushing conductor, and a bushing flange in circumferential arrangement to the bushing; wherein the transformer casing has an opening adapted to receive the bushing assembly or part thereof; and the bushing flange is mounted on the outside of the transformer casing and secured thereto by engaging the locking means on the inside of the transformer casing.