An electrical receptacle mounting apparatus, having a base portion, made of insulating material, and including a partial enclosure, defining a cavity having a mouth and a through-hole, and being positioned and shaped to prevent water flowing through the through-hole out of the cavity. Also, a panel, extends outwardly for more than 4 cm about the mouth and a telescoping tubular extension, made of insulating material, is fitted into the cavity, so that cavity and extension together are sized to fit a one, two or three electrical receptacles. Additionally, a bolt has a longitudinal segment that is rotatably engaged to a first one of the base portion and the extension, and has a threaded portion being in threaded engagement to a second one of the base portion and the extension, so that rotation of the threaded element causes the extension to move in telescoping manner relative to the cavity.