Russell Baron

Sat 10 May 2014 11:37pm

Hi Steve A 10.5kw shower is far too powerful for a 30A fuse and therefore would trip on overload. The cable to this shower should be 10mm twin and earth also Basically a 10.5kw shower is 10500 watt, divide by 230v equals 45.65 amps design current I would ask the electrician to return and explain why he's put the shower on a 30a fuse when the shower pulls 45amps when running

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Andrew Procter

Sun 11 May 2014 09:51am

Hi Steve, Russels calculation are right, so there should be a 50A breaker for overload protection. The RCD should also be able to take at least 50A of healthy circuit current with a 30mA trip rating for earth faults. Hope this helps cheers Andy

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Bogdan Banasiewicz

Sat 10 May 2014 10:23pm

Hi Steve. If 40 Amp RCD not tripped but 30 MCB tripped , electrician should check reason of non tripping RCD and also check current for shoer circuit . RCD tester tell you abou condition of RCD unit . 40 Amp RCD will tripped when fault is in circuit and protect you against electrical shock or overload of circuit. In your case is not necessary to replace RCD because value of RCD is 40 Amp and if current in shower circuit will be about 38 Amp and no fault in circuit , RCD will not tripping but MCB will due to 30 Amp current . No bypass . regards Bogdan

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