PURPOSE: To permit a serviceman to make service safely and remove an electric source cable simply upon the trouble of the device by providing a connecting cable connecting the electric source cable, taken out of the equipment, with a plug socket.

CONSTITUTION: An electric source cable 17', taken out of the equipment 1', and the plug socket 14, provided on the wall behind the equipment, are prepared and a connecting cable 20, connecting the electric source cable and the plug socket 14, is provided separately from the electric source cable 17'. As a result, the cable 17' is not removed from the plug socket 14 and is permitted to remove it from the other cable 20 connected to the plug socket 14, therefore, the electric source cable 17' will never be damaged and the safety of the cables may be secured perfectly upon the service of the device or the like.