Using a simple multimeter I have discovered around this home (what I may be mistakenly calling) "stray voltages", i.e voltage potentials across appliances' metallic parts that should not have a voltage potential.
The home is located in Eastern Europe, Romania. Where outlet voltage is 220-240 VAC. It does not have a protective earth / grounding system installed (tested using a simple socket tester, and confirmed by the home owner it was never installed).
At the breaker panel there is an RCBO which should trip upon detection of any residual current or ground fault larger than 300mA, or an overload larger than 20A (which may be a rather big limit considering the wires in the walls appear to be at most 2.5 sq-mm cross sectional area).
I am not an electrician, nor the home owner. I am just a temporary guest, observing and trying to assess the safety of the place (which looks concerning to me), while I'm staying.
I tried my best to describe and present the suspicious measurements in this video. Make sure to enable subtitles. https://www.youtube.com/watch?v=bflTOGjgSKM
The sparks in the video were produced with the multimeter set to measure 10A DC max current, so it allowed current to pass through the probes. I don't know what the current was, because my multimeter does not measure AC current, but the RCBO did not break the circuit. No sparks were produced when measuring voltage.
The stray voltages around the kitchen sink are all caused by the washing machine being plugged in. With the washing machine plugged out the sink-gas cooker, sink-gas pipe, and sink-radiator voltages turn to 1 or 2 volts. I think the reason is that the washing machine has water hoses connected under the sink.
Sneaking a peek inside a wall junction box reveals this wiring:
I don't know what the code specifies, but things don't seem to be looking pretty inside here. I don't think it was done by a professional, and I don't forsee a profesional electrician being called by the home owner anytime soon, nor a protective earth installed in the near future.
In spite of that, what safety measures can I still take to make sure I don't die while staying here?
Would it be a good idea to bring the appliances' casings to the same potential somehow? Pluging them into the same extension cord, which has a ground pin connection? Even though they will not ultimately be connected to ground, would that bring their casing potentials to the same level and reduce the risk of an electric shock? Or rather increase the risk?
Could the voltage found at the casings be induced by an electromagnetic field inside the appliance, without direct contact, and therefore not dangerous because it won't produce high enough current (hence the RCBO not tripping)? Or is it just that the RCBO is not sensitive enough?
Is it common to have stray voltages like these in homes without a grounding system?
Update 2: I installed a 10mA C16 RCBO externally, dedicated to this outlet. Inline with an extension cord which will be used to supply power to the washing machine, fridge, and some other appliances. I don't think this is an ideal solution. But it has the advantage of being portable, and was the best I could do for now, since it is not my home.
About the inexistent grounding system I'm not sure there's much I can do at the moment.
I could be able, for example, to use external wires and bring the ground of this extension cord outsie and connect it to a metal rod driven into the soil. But I cannot do that for every outlet, and I will end up with some grounded and some ungrounded appliances around the house, which I'm not sure is a good idea. And after some more research I think is not a good idea from other reasons too, and even illegal in some countries.