Went into the workshop the other day and the power was off. After half an hour of cursing and swearing the fault turned out to be that my ultrasonic cleaner had leaked water through the stainless steel tank which banjaxed the circuit board.
The main RCD detected this, hence the power cut.
I was surprised to find a sizeable (1mm) hole eaten through the stainless tank. I suppose stainless does not mean stainless in all cases.
The machine was this generic type: http://image.made-in-china.com/4f0j0...ertificate.jpg
It lasted 3 years and was actually very effective.