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Rcd or mcb


I am having a kitchen/ living room together. There will be new circuit for the sockets and appliances.

Does a combi boiler need to be on its own circuit?

Do i need a new consumer unit with RCD or MCB. I need to have a part cert from the council.

In what order do the breakers come. So i a RCD better than a MCB?


2 Answers from MyBuilder Electricians

Best Answer

You need a qualified electrician the work is notifiable Part P building regulations and the building inspector must be informed before the work starts or a registered domestic installer has to carry out the work and notify it afterwards.
a Combi boiler does not require its own circuit it can be spurred from a ring main or be part of a radial circuit,
a Residual Current Device (RCD) works on earth leakage and only protects if there is an earth fault
a Miniature Circuit Breaker (MCB) works on over current
they do totally separate jobs
last question in what order do the breakers come oh boy! do you need an electrician
please do not attempt to carry out any electrical works yourself it is very dangerous put the job up on sit back and relax knowing you will not burn the house down or electrocute someone and the job will be carried out by a professional safely and at a very good price


Answered 25th Aug 2011

To avoid nuisance tripping of the RCD in the event of a boiler fault it would always be best practice to wire a separate circuit for the boiler. However as the other reply has said its perfectly safe and compliant to be spurred off the sockets ring, which is probably the most common method.

The best solution would be a new fuseboard with separate RCBO's (thats an MCB with built in RCD) as this reduces the chances of a fault on one circuit affecting others. - Get an electrician to give you some quotes for the various options.


Answered 18th Oct 2011

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