Hi all.
My brother is having a problem with his electric shower. You know the sort, the instantaneous ones which heat the mains cold water as it passes through. It keeps tripping the MCB. There is nothing else on the circuit, which is also RCD protected. It hasn't always happened, but it is now occuring very frequently. The MCB is rated at 40amps, and the shower is a 9.5 kilowatt unit (at 240volts).
Any ideas on what could cause the MCB to trip before the RCD, given that the shower shouldn't be pulling more than 40amps?
I guess the simple answer is that somehow the shower *is* pulling more than 40amps, or the MCB is naff and trips too easily.
Cheers Simon