Sorry Paul,
At the time of posting that message, I was in a bit of a panic here, as the roof timbers were creaking and carrying on, with the weight of all the snow on it.
What resulted, was I only told some of the story,here's the rest!. [Linked Image]
What had happened was, the owner of the Lathe, had hooked it up himself and he thought that with having a Blue wire, a Yellow wire and a Red wire at the lathe, as well as the Earth wire(Green), that he would hook up the Red and Yellow wires as per normal(he still had an empty B terminal, when I turned up).
The Blue wire(that he thought was a Neutral) was joined to the frame of the Lathe, with the Earth wire, when I asked why this was so, he replied, "because it's like that at the switch-board".(Older MEN switchboards, here used to have the Main Neutral and Earth solder lugs on the same stud on the Neutral Busbar, along with the Range Neutral)
Must have gone off, with a big bang!.
Regarding the fusing, the HRC's fed the MCB and then to the Lathe sub-circuit, which also had no isolator.
I have since been back to fix all of this up, it's fed via HD Flex and a chemical-proof isolator(because of the cutting fluid). [Linked Image]