The only way that immediately springs to mind is so unlikely to happen. It requires multiple faults/mistakes.
1: The chassis of one of the two units became live (connected to “hot” for you Americans) but was also not grounded in any way.
2: The chassis of the other WAS grounded and created a circuit for the current to flow.
3: There was no RCD (GFCD or whatever you guys call it) on the circuit.
In this way, that pipe would be the only thing connecting the two devices, and the resistance is causing a huge amount of heat (just like an incandescent bulb, or a heating element does by design).
Probably other possibilities, but it’s just the first thing I could think of that could potentially produce this result. But, that’s a lot of safety features to have either failed or just simply not been in place for this to be possible. So, frankly I hope I’m totally wrong.
The only way that immediately springs to mind is so unlikely to happen. It requires multiple faults/mistakes.
1: The chassis of one of the two units became live (connected to “hot” for you Americans) but was also not grounded in any way.
2: The chassis of the other WAS grounded and created a circuit for the current to flow.
3: There was no RCD (GFCD or whatever you guys call it) on the circuit.
In this way, that pipe would be the only thing connecting the two devices, and the resistance is causing a huge amount of heat (just like an incandescent bulb, or a heating element does by design).
Probably other possibilities, but it’s just the first thing I could think of that could potentially produce this result. But, that’s a lot of safety features to have either failed or just simply not been in place for this to be possible. So, frankly I hope I’m totally wrong.