Does this look like an earthing issue? Meter readings attached

[measure_twice]

Hi folks. I am regularly experiencing tingling shocks from my laptop and kettle. Both of these things are plugged into something with a ground plug.

I decided to measure the neutral to earth voltage, at least for the nodes I can reach at my plug. I see significant AC voltages measured between the ground pin and the neutral: maybe 90 V or so. I'm not sure in this house wiring which pin is line and which is neutral, but I've included photos of four relevant measurements in this post.

I would have expected one of these measurements to come out low: perhaps 0-10V AC. Instead, they all look like either our nominal 240V here in Rwanda, or some point halfway between line and neutral.

Does this seem like an earthing problem? Also, could this indicate significant imbalance in my area, which the utility should do something to correct?

Also, if I do provide a solid earth between the panel ground and physical earth, can I expect a pretty big neutral current? I'm inviting an electrician to my house (as I am an electrical engineering professor but know my limits and respect technicians) but curious what you folks think, and thanks for your attention to a first time post!

 

[telectrix]

i would say that you have no earth. can you use a long lead and measure resistance from earth terminal on a socket to the main earthing terminal.

 

[Lucien Nunes]

Agreed, your initial diagnosis is correct, the resistance to earth is so high as to be in the same order of magnitude as the input resistance of the meter and the reactance of the cables' stray capacitance at 50Hz. Something is disconnected somewhere.

I would vary Telectrix's test to say first measure the voltage between the offending socket earth and main earth terminal, and then measure the resistance only if it is found to be minimal. The latter being to prove that the connections on that part of the wiring at least are sound.

 

[measure_twice]

Thanks @Lucien Nunes and @telectrix . I'll first see if I can find a long lead. Actually, first I have to confirm that there is an earthing terminal *somewhere* in the house. I found the breaker panel, and I expect somewhere near that should be a main disconnect. It's likely in the attic, where the service enters the building. So it will be a pretty long lead! Will be careful and keep you posted.

 

[littlespark]

I’m sure with your background you know which tests can be done live and which ones need to be performed with the power off.

 

[measure_twice]

Yes @littlespark I should hope so- keeping myself and most equipment alive so far.

The update is that I retained a local electrician to earth my house: it's great now, no shocks.