try turning the controls to cold and low then turn it on. it should start and run for a little while maybe. doing this you are only running the pump on its own (no heating element)
as you increase the heat and pressure control the trip switch (mcb/rcd or rcbo) should trip because it will take to much current (amps)
if this happens you need to check what size cable is going from your fuse board to your shower. it needs to be 10sq mm for the shower you have fitted.
if it is not 10sq mm then just exchange your shower for something of less KW's. try something around 8kw.
if the cable is of the correct size then you need to make sure your trip switch (mcb/rcd or rcbo) is rated correct. maybe 45amps.
hope this helps.
Eanna
December 2007