AC Phase, Neutral, Earth Fault Indicator Circuit

The circuit explained here will provide LED indications and show if there's a possible fault in the wiring of your home AC Phase, Neutral, and Earth connections. The idea was requested by Mr. SS kopparthy.

Technical Specifications

sir, very good morning. I thank you for your help. I further wanted you to consider a circuit whose pics are attached with links given.

This pcb would indicate me when earth is leaking(at that time the tester would burn when touched to earthing pin in 220v socket and will get a strong shock when touched by mistake.

Even the metal bodies of appliances give shock at that time.) by switching on the first two led's.if you look at the attached pics, you can see that the circuit has only a few resistors and diodes, and a black colored capacitor at back.

i also tried to draw the circuit diagram by seeing that pcb. the same pcb indicates the fuse blown condition.for circuit diagram and pictures of pcb, please see "

sir, i hope you understand the working of circuit and also hope you'll tell how its working to me also.......the purpose of writing this is that i would like you to help me by designing the circuit which has buzzer with led indication when something goes wrong. thank you very very very very very very very very much sir.........i cannot forget your help......

Using 3 LEDs for the Indications

The above circuit can be much simplified and implemented using a just three LEDs and some resistors.

The circuit may be understood as follows.

The design of the proposed LIVE or phase, neutral, earth indicator circuit is rather simple.

As can be seen in the given diagram one LED is connected across the phase/neutral, another LED across phase/earth and a third one across neutral/earth.

Each LED has its own limiting resistor rated at 56K 1 watt.

The illuminations from the LEDs in response to the different L/N/E faulty conditions could be witnessed as given under:

LED1 and LED2 ON and LED3 OFF indicates a good overall situation wherein the phase, neutral and earth could be assumed to all wired correctly.

LED2 and LED3 ON and LED1 OFF indicates a wrong polarity of phase/neutral but earth and neutral may be assumed to be rightly configured.

All three LEDs ON indicates an open earth or neutral which may be diagnosed further. Since an open neutral is rare, the possibility of an open "earth" could be considered and investigated.

In addition to the phase, neutral, earth fault indications the circuit also employs a blown fuse indicator in the form of LED4 which simply lights up if the fuse is blown or open and a appliance hooked up.

Note tat the polarity of the LEDs are not crucial and could be used any way round.

Use of red LEDs is recommended, other types could show unusual responses.

The earth leakage sensor and buzzer circuit will be soon updated.

Simplified Schematic