Abstract: An electrical socket for use with a spigotted plug and intended primarily for implantation in a human or animal body, for instance to connect an electrode catheter to a cardiac pacemaker casing. The electrical socket has a body defining a bore in which an insulating body portion of a plug member may be received in a sealing manner. A block of conducting rubber is positioned in the bore and has a first recess in which the plug spigot may be received, the cross-section of the spigot being greater than that of the first recess, so that the block is deformed as the spigot enters the recess, to make an electrical connection therewith. A second recess is provided in the block of conducting rubber, spaced from said first recess, to allow accommodation of deformation of the rubber material on a spigot entering the first recess. A contact extends through the wall defining the bore, to connect with the block. The conducting rubber may be a silicone rubber loaded with platinum, titanium or carbon particles.