The distribution box is assembled according to the requirements of electrical wiring. The switchgear, measuring instrument, protective appliance and auxiliary equipment are assembled in a closed or semi-closed metal cabinet or on the screen to form a low-voltage distribution box. In normal operation, the circuit can be switched on or off with the aid of a manual or automatic switch. In the event of malfunction or abnormal operation, the circuit or alarm is cut off by means of a protective device. The measuring instrument can display various parameters during operation, and can also adjust some electrical parameters to prompt or signal the deviation from the normal working state.