These are used when the cable is removed from a machine or apparatus frequently. The most common type is the 100-amp British Standard plug and socket, and it is employed to connect the trailing cable to a coal cutter or face conveyor. The gland of the plug is arranged to grip the sheath of the cable and to make connection with the screen and earth core. Power and pilot conductors are connected to the appropriate contact tubes, which make connection with corresponding pins in the socket portion.