I had a bit of a phenomenon on the neighbour's electrical circuit.
What was observed:
- The differential had blown
What was tried:
- I tried to to isolate the faulty circuit by trying to get the differential stay closed.
- Trial and error resulted in several circuit breakers set to "open" until this was managed, with no obvious pattern. For example, the circuit breaker for the fridge and the circuit breaker for the oven both had to be "open". Closing them would trip the differential. Even then, the differential randomly tripped after maybe 5 minutes of stability.
What fixed it:
- The neighbor remembered a dodgy lamp plugged in. It was indeed doddy, as the power supply was broken open with the transformer spool clearly visible and the grounding cable had broken loose.
- After unplugging said lamp, all the ciruit breakers could be closed and the differential could be satisfactorily closed and stayed this way.
- I'm not sure whether I "isolated" that lamp through opening one of the ciruit breakers earlier, but probably yes (judging from the inscriptions on the breakers at least).
How is it possible that a single device on the "power plug" circuit causes the circuit breaker of the "stove" or "fridge" circuit to become differential-triggering-when-closed?
I actually suspected a major problem with the cabling at first, like water intrusion or a rat having a final meal. I reckon one should have a professional take a good look at this phenomenon?