The automatic mains-field disconnector NFA monitors the circuit and switches off the mains voltage when the last load in this circuit is switched off. In this way, it also de-energizes electric fields which, as is now known, have a negative influence on the human body which should no longer be ignored. These devices are recommended above all for bedroom circuits (rest areas). The NFA 63 can also be switched on by external activation via its additional control input (B1). In this way, a fixed power supply can be assured at certain times of day with the aid of a timer, for example.