when i put the main power on then try to switch the triton t80i on it turns the main power to the shower off.

m wrathall, November 2009

Does it trip your RCD? If so then there is an electrical fault and your household protection is operating as expected and electrical engineer would need to pinpoint it. (blown elements, dodgy switch, breakdown in wiring). My guess would be a blown element.
Good luck

Paul M, November 2009