Thanks plugwash, I think you're on to something there.
It doesn't work on 'low' either.
Do you know if I need a whole new Can Assembly? Have found the parts here:
http://www.tritonshowers.co.uk/wps/wcm/connect/TritonShowers/Internet/Spare+Parts/
My Triton T90i shower has just mysteriously started tripping the ELCB at my main fuseboard.
This happens immediately on turning on the shower at full power but oddly does not happen if the power is turned down to Medium.
I've opened the shower and saw some black dust that I suspect is from the...