ring main mcb size?

[jaffadutch]

Hello all,

I have a ring main upstairs in my house.
There are only 3 sockets on it.
Two single and one double....its protected by a 32A mcb...isnt this two big? Should it not be 20A?
I have a onsite guide but dont understand 100% of largest demand plud 40% of all others? Is 13A my largest demand or would it be what my hoover takes for eg?
Can anyone help? I would like to know im protected!

cheers

Jaffa

 

[plugwash]

protection and diversity are two totally seperate subjects.

provided the cuircuit is actually wired as a ring with 2.5mm cable then its perfectly safe to have it on a 32A breaker regardless of the number of outlets on it.

diversity is about taking into account the fact that not everything will be on at once when deciding how much power to allow for in your designs. you could design a system capable of supplyin a full 13A to every socket at once. Its something of a black art and whilst there are guidelines in the regs they tend to lead to a gross overestimate of the total power requirements of a domestic installation.

 

[mapj1]

The socket contacts and applience plugs and cables are protected by the 13A (or less) fuses in the plugs. Therefore the most you can take from any one socket is limited to 13 amps (~3000 watts)

The MCB protects the cable against overload. If the cables are wired to form a proper joined up ring and has live and neutral cores of 2.5mmsq cross-section or larger, then it is fine. You probably never will trip the breaker of course, but that is the whole point (unless you nail into the cable or something equally unlucky) .
You will probably never blow a company fuse either, but that doesn't mean its not doing its job just fine