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.
Even if that happened, wouldn’t the pipe handle a lot more current than normal house wires, or even the main ones connecting the building to the grid. I assume the pipe would be thick enough that the wires in your walls would be glowing long before the pipe itself was.
I would have thought so, but I think it depends on how thin the skin of the pipe is. I would also have expected a breaker to trip under that much load. But, based on that happening, I’d not be surprised if there are bypasses and/or broken breakers.
When we moved into the house we’re in now, the RCD (GFCI) didn’t work at all. I pressed test, nothing. Had the electrician over to change it. He tested the actual actuation using earth leakage. Nothing. So, faults can happen too.
I want to be wrong, though. Because that’s a pretty bad state to get into, I think.
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.
Even if that happened, wouldn’t the pipe handle a lot more current than normal house wires, or even the main ones connecting the building to the grid. I assume the pipe would be thick enough that the wires in your walls would be glowing long before the pipe itself was.
I would have thought so, but I think it depends on how thin the skin of the pipe is. I would also have expected a breaker to trip under that much load. But, based on that happening, I’d not be surprised if there are bypasses and/or broken breakers.
When we moved into the house we’re in now, the RCD (GFCI) didn’t work at all. I pressed test, nothing. Had the electrician over to change it. He tested the actual actuation using earth leakage. Nothing. So, faults can happen too.
I want to be wrong, though. Because that’s a pretty bad state to get into, I think.