On 30/10/2020 09:20, R D S wrote:
A machine at work hadn't been used for a week, switched it on and BANG!

Turns out the inverter in it (Moeller DF4-120) is knackered, there is
blackening on the circuit board.

It's usually something obvious isn't it?

Upon closer inspection having removed the motor to have it tested, the
cable was out of the gland/grip and there was damage to some insulation
where it had rubbed against the side of the housing, probably during a
recent move where it was unceremoniously dragged up a flight of stairs.
(Presumably the same debacle causing the earth to come off it's
connector at the other end of the cable.

Anyway, another lesson learned, periodic checking of such things,
especially after moving stuff around.