A radio-frequency (RF) controlled switch box without using Neutral wire includes a relay, and an RF controlled circuit that receives an RF control signal to control open or closed state of the relay. The RF controlled circuit, the relay and a light-emitting diode (LED) light bulb are connected in series between Line wire and the Neutral wire. The RF controlled circuit includes a voltage clamper. When the relay is closed, mains voltage between the Line wire and the Neutral wire is distributed between the voltage clamper and the LED light bulb, such that the voltage clamper generates a clamped voltage and the LED light bulb turns on. When the relay is open, the RF controlled circuit takes power from a rechargeable battery.