A system including a base and a module to be inserted into this base, an electric relay to electrically disconnect the module from the base, and a blocking device that can change over from a blocking state to a release state. The system including a sensor to detect the presence of the module in the base and a blocking sensor to detect the state of the blocking device, and means for opening the relay as soon as the blocking device is released or as soon as the module is not present. The blocking device can leave its released state only when the module has been extracted from the base by a distance more than the detection distance of the presence sensor.