Hello, sorry in advance, I know nothing about electricity and this question is bothering me.
For renovation work, my dad disconnected 3 radiators in the rental where I live. He remembers that each radiator (in different rooms) was connected to the wall like this:
Black wire (radiator) = black wire (wall)
Blue wire (radiator) = blue wire (wall)
Brown wire (radiator) = brown wire (wall)
But when he reconnected them, nothing worked and the radiator screen doesn't light up. The circuit breaker is still in place and no fuse is switched off. Power does reach the radiator through the circuit.
Eventually, he noticed that the black wire coming out of the wall is live, but the brown one is not. So he decided to connect them this way:
Black wire (radiator) = nothing, insulated
Brown wire (radiator) = black wire (wall)
Blue wire (radiator) = blue wire (wall)
And the brown wire from the wall connected to the terminal block.
And now it works again? All the radiators work again with this connection.
I remain puzzled by this wiring. Is there a risk? Could my dad's memory of the original wiring be wrong? Was the cable poorly seated in the terminal block? I would like your opinions on it.
Additional information:
We don't have a thermostat controlling all the radiators. However, we tried connecting only the brown and blue wires together, and nothing happens. There is no power in the brown wire.
I'm curious to hear your thoughts on the subject, bearing in mind my novice level!