After about 3 or 4 mins normal use the shower cuts off completely,(usually when you are well soaped up) and trips the breaker in the consumer unit.
If the shower is left alone for 5 mins then reset at the
consumer unit,another 3 mins normal use then BANG
again!!
I believe the shower unit is 10.5 kw,and also the culprit!

Paul, April 2009

Sounds like the mcb breaker is not correctly rated, for a 10kw shower you would be looking at least a 45 amp rating type b mcb. But before you go uprating it check the shower cable is also the correct size, it should be 10mm cross section area. Above all else get it all checked out by a part p approved electrician.

Phil Morley, April 2009