Abstract: An electrical connector, such as a domestic supply plug, utilizes a cartridge fuse (60) clamped within a receptacle or cage comprising two parts (61, 62) which snap engage together in a permanent fashion. The cage part (61 or 62) or both have spline or key formations (63) on an outer surface while the plug body (64) has a cavity (65) extending from an outer surface and includes channels or keyways (66) complementary to the spline or key (63) on the cage. The fuse and cage assembly may thus be pressed into the body of the plug with the spline forming the key such that only the correct fuse assembly may fit the chosen plug.