My Opal 11 will run on hot setting for a various period of time then trip out the RCB, Turning the shower off and the mains power source then resetting the trip wait 5 mins and the shower then functions correctly. The a few days later the problem comes back and the shower trips out after about 5 minutes use.
Your electric shower unit is drawing more amps than the RCB is designed for. You will have to uprate the RCB to a higher rating. Make sure that your switch and wiring can cope with extra power or you could burn out the wiring and switch. A 6mm cable rated at 47amps is what you require.
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