The main switch you said is the same as the indoor wire, but it can control the on-off of the power supply; When alternating current passes through a conductor, it does form an "alternating electromagnetic field" around the conductor, but it is only a "power frequency magnetic field" with a frequency of 50Hz. It is surrounded by this power frequency magnetic field in people's "life circle", so far no one has been hurt by this power frequency magnetic field, you can rest assured. Simply put, the main switch of power supply plays the same control role as the switch of lamps such as desk lamps on the wall. Aren't you "worried" that it will hurt you?