Abstract: A device intended to receive two or more electrical conductors of the same or dissimilar size and to provide mechanical protection and electrical insulation for the electrical connection of said conductors, including a container for receiving the joined ends of the electrical conductors, the device including having side walls, a closed end wall and an open end and a plug member adapted to seal the open end of the casing. Passages are provided in the plug end or closed end for the extension therethrough of the electrical conductors. Cooperating locking means are provided on the plug and the casing member for mechanically interlocking the plug end casing and radial flaps are disposed in the passages which are deformed by the extension therethrough of the electrical conductor to define a cone shaped collar between the passage wall and the condutor to impede the flow of potting compound out of the device.