to the vertices of a square member in a substantially central position relative to the base wall of the box like body the plug c is designed to be connected to a flexible cord k which is assumed to be of indeterminate length and which carries at one of its ends a connector 10 u2032 the reason for this term will become clear in the following text having four sockets 100 when the end of the flexible cord k carrying the connector 10 u2032 is coupled to the plug c the four sockets form corresponding cylindrical or more generally tubular cavities for receiving the pins c 1 which are inserted into them as will become apparent from the following text the sockets 100 of the connector 10 u2032 are connected to corresponding conductive lines or tracks 12 applied using known lamination methods for example to a strip like substrate 14 of the cord k as is shown in fig5 to 7 only for reasons of simplicity of illustration in various embodiments the body of the cord k is shaped overall in the form of a channel in which it is possible to identify a core wall defined by the strip 14 on which the lines 12 are located and two end walls 16 in this arrangement the volume of the inner cavity of the channel shape is filled with an insulating material 18 designed to protect the conductive lines 12 provided on the strip like substrate 14 so as to provide electrical protection of the lines 12 in accordance with the ip standards for example in various embodiments cords k of the type considered herein can be produced from a continuous strip of virtually indeterminate length in which the substrate 14 with the lines 12 formed on the surface.