Abstract: A housing for an electrical apparatus, which is an integrally formed plastic member having a sloping wall with a number of sloping-trough depressed areas formed therein, the upper extremity of each such depressed area being deepened and having a discontinuity relative to the adjacent wall portion, thus forming an opening for the escape of warm air from inside the housing. The wall slopes in one direction relative to the horizontal, and the open face of each discontinuity-formed opening slopes in the opposite direction, so that liquid falling upon the sloping wall tends not to enter the openings but instead to flow downward along and off the exterior surface of the housing.