LED indicator device for AC power plug or socket

An LED indicator device is mounted in an AC power plug or socket and electrically connected in parallel with an AC power source. The LED indicator device includes a driving/current-limiting circuit to which an LED lighting circuit is coupled. The driving/current-limiting circuit includes a driving/current-limiting capacitor and a discharge resistor connected in parallel with the driving/current-limiting capacitor. The LED lighting circuit includes an LED, a protective instantaneous current-limiting resistor coupled to the LED, a rectifying diode connected in parallel with the LED, and a protective instantaneous voltage-limiting capacitor connected in parallel with the LED. The LED is lit to show the position and on/off state of the AC power plug or socket. Three LEDs emitting different colors and associated driving/current-limiting circuits and associated LED lighting circuits can be utilized to indicate incorrect power connection or short circuit of the AC power plug or socket.