- #1
- 2,128
- 2,701
We are facing a severe earthing problem. In our house, the potential difference (PD) between neutral and earth is ## 50 - 60 ~\mathrm{VAC},## which should normally be ##< 2~\mathrm{VAC}## if earth is properly connected. I determined this with my multimeter after some appliances were giving electric shocks. And this value is approximately the same in all outlets inside our house.
Now, I am trying to figure out whether the issue is only in our flat, or throughout the building.
Here is a diagram of the main circuit board in our building:
There are three lines (phases?) (red, blue, yellow) and a neutral (black) that enter the building. I have not shown the electricity meters, as they're not required. Also, the neutral wires from each fuse (F1-6) are actually separate wires that meet at the company fuse (point D) for the neutral line (similar to the earth wires, which meet only at E).
I measured some potential differences, and the list is as below:
Our fuse box (F1) is made of metal, so the earthing wire that comes down from our flat is first connected to that metal box, and thereafter connected to point E. I also checked the PD b/w this box and point E, and it was ##\approx 1.5 - 2~\mathrm{VAC}.## It shows that earthing is fine at the main board, so something is wrong in the wires between our house and the main board. We shall be calling an electrician to rectify it.
But I discovered something more. There is a three-pin socket from the common place line near the entrance of our building (it is indoors). I checked the PDs at this location, and found this:
Note that I rechecked these twice. But I didn't verify it by checking with F6, the common place fuse.
I am interested in why the value ##40.6~\mathrm{VAC}## comes up, and whether it is of any significance.
Now, I am trying to figure out whether the issue is only in our flat, or throughout the building.
Here is a diagram of the main circuit board in our building:
There are three lines (phases?) (red, blue, yellow) and a neutral (black) that enter the building. I have not shown the electricity meters, as they're not required. Also, the neutral wires from each fuse (F1-6) are actually separate wires that meet at the company fuse (point D) for the neutral line (similar to the earth wires, which meet only at E).
I measured some potential differences, and the list is as below:
Multimeter probe 1 location | Multimeter probe 2 location | Potential Difference (in ##\mathrm{VAC}##) |
---|---|---|
Company fuse for neutral, point D | Earth, point E | ##\approx 0.5 - 1.1## |
Neutral at F1 | Earth, point E | ##\approx 0.5 - 1.7## |
Live at F1 | Earth, point E | ##\approx 229## |
Live at F1 | Neutral at F1 | ##\approx 230## |
Our fuse box (F1) is made of metal, so the earthing wire that comes down from our flat is first connected to that metal box, and thereafter connected to point E. I also checked the PD b/w this box and point E, and it was ##\approx 1.5 - 2~\mathrm{VAC}.## It shows that earthing is fine at the main board, so something is wrong in the wires between our house and the main board. We shall be calling an electrician to rectify it.
But I discovered something more. There is a three-pin socket from the common place line near the entrance of our building (it is indoors). I checked the PDs at this location, and found this:
Multimeter probe 1 location | Multimeter probe 2 location | Potential Difference (in ##\mathrm{VAC}##) |
---|---|---|
Live | Neutral | ##230.1## |
Live | Earth | ##40.6## (?) |
Neutral | Earth | ##7## (?) |
Note that I rechecked these twice. But I didn't verify it by checking with F6, the common place fuse.
I am interested in why the value ##40.6~\mathrm{VAC}## comes up, and whether it is of any significance.