Can one more wire in the wall switch box be used as the zero line?

Generally, there is no zero wire in the wall switch box, one of which is a live wire, which is connected to one end of the switch, the other end of the switch is connected to another wire for lighting, and the other end of the lighting is connected to the zero wire. If the extra wires in the switchboard may be used to control another lamp, try to find the controlled lamp and make sure it is not used. You can connect the wires at both ends of the lamp together, and the extra wires can be used as the zero line. If you want to connect the socket, you should consider whether the capacity of the wire diameter is enough.