As well as that, as I pointed out, the regulation is written for a BS3036 30A fuse so the cable has to be derated by the 0.725 factor.
27 x 0.725 = 19.575.
Therefore, it is not really possible to match values to a 32A MCB with the mandatory things you must do.
Yes, but it does not allow you to use a 20A cable (except MICC); you must use a 27A 2.5mm² T&E.
Obviously it cannot. See above.
That is not the correct answer.
Using 4mm² cable it would not need to be a ring final; it could be a radial; therefore the question is invalid.
433.1.204 Accessories to BS 1363 may be supplied through a ring final circuit, with or without unfused spurs,
protected by a 30 A or 32 A protective device complying with BS 88 series, BS 3036, BS EN 60898, BS EN 60947-2
or BS EN 61009-1 (RCBO). The circuit shall be wired with copper conductors having line and neutral conductors
with a minimum cross-sectional area of 2.5 mm2 except for two-core mineral insulated cables complying with
BS EN 60702-1, for which the minimum cross-sectional area is 1.5 mm2. Such circuits are deemed to meet the
requirements of Regulation 433.1.1 if the current-carrying capacity (Iz) of the cable is not less than 20 A and if,
under the intended conditions of use, the load current in any part of the circuit is unlikely to exceed for long periods
the current-carrying capacity (Iz) of the cable.
No sums necessary.
