Power shower problem

[Hagbard]

I have a Mira Event power shower which I installed about 5 years ago. It is connected through a double pole switch and a RCD/FCU. The shower has worked fine until today, when the RCD tripped. A substitute RCD also tripped which would suggest that the fault is in the shower or the cable between it and the DP switch. If the shower is turned on with the RCD off, and the RCD is then reset, the motor runs normally and does not trip the RCD if the DP switch is turned on or off. However, if the water flow control is turned to 0 the RCD trips about 5 seconds after the shower stops.
Inside the shower case there was a lot of carbon dust but blowing this out with an air duster made no difference.

Before I call a sparky are there any common faults with this type of shower that could be causing these symptoms?

 

[delmel]

HAve you resolved ?

It sounds like a fault inside the shower, is it completely dry inside when you remove the casing. I have this shower myself and although mine is brand new i noticed the seal inside the outlet wasnt seated correctly. This overtime would have got worse and a water ingress would have been a fault. I would suggest calling Mira rather than a sparks as he will not have the spares required, and mira have there own force of engineers on the road.