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I was thinking of buying a Residual current device but I don't know if the power supply to my home is grounded properly or not. For initial testing I used my multimeter to check the voltage coming to my home. It was 220 V.

Then I checked each terminal from the power switch and compared it with the ground ( Had a metal rod dug very deep in the ground).

It was 217 V with respect to the hot wire and 3 V with respect to the Neutral Wire.

I was expecting to be a 0 V difference with respect to the Neutral wire. But it was constantly showing 3 V. I checked it many times.

Now, my question is,

  1. Am I measuring it correctly? Is there any flaw?
  2. Will the RCD trip in current situation?
  3. Should I go ahead and buy one? If not then is there any way to fix the situation or any other device like RCD for the current situation?

PS, I even used the multimeter to check the continuity of the Neutral wire with the metal rod. It did not beep.

Hemant Yadav
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    "*I even used the multimeter to check the continuity of the Neutral wire with the metal rod. It did not beep.*" Bad idea. You had already read a voltage between the two. Continuity and resistance test is for dead circuits only. – Transistor Oct 26 '20 at 20:41
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    3V is a reasonably healthy neutral potential, assuming you're somewhere that grounds Neutral at the substation/transformer rather than in your house. RCD doesn't need a solid GND to trip, just imbalance between L and N currents (implying some current is going elsewhere). Go ahead and get one fitted. –  Oct 26 '20 at 20:46
  • @BrianDrummond, I think that's for TN-S. Is that the case here, is the OP in the UK? Just a general comment to other readers: in NA it's TNCS and the G/N voltage would be 0V. – P2000 Oct 26 '20 at 21:37
  • @P2000 I don't think he's in the UK, he didn't mention an incoming Earth alongside his Neutral. –  Oct 26 '20 at 21:56
  • @P2000 No, I am not from UK, I am from India – Hemant Yadav Oct 27 '20 at 04:13
  • @BrianDrummond, Actually I read somewhere that RCD won't work with a floating voltage, will it? I mean, you will get an imbalance in currents with a floating voltage as well, right? – Hemant Yadav Oct 27 '20 at 04:39

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