[Bookman]

There is perhaps a slight misunderstanding of usage associated with equipment ratings. In this I would refer first to cable sizing which must be rated to carry safely the nominal expected and/or calculated load current of the circuit over the length of cable employed.

Fuses however are over current devices that are used to isolate power to the circuit under varying fault conditions hence the types of fuses that are available. MCBs incidentally have a range of IDMT (Inverse Definite Minimum Time) tripping characteristics curves that attempt to mirror more accurate fuse curves.
Here it is important to bear in mind that most if not all electrical installations will have fuses or breakers that will need to have some form of coordination. For example you would not want your trailing socket to blow an upstream fuse and put all the lights out.
It is to be noted that certain MCBs will in fact have internal fuses fitted owing to their inability to provide short circuit protection for given applications.