Re: Transformer question ?
Is this a trick question? There is no ?minimum? size circuit breaker. Protect it with a 1 amp fuse, if you like, and if you don?t mind the ?occasional? nuisance trip.
The NEC gives ?maximum? limits, in order to provide protection for the transformer and for the conductors that it feeds. Table 450.3(B), far right column, for currents under 9 amps, limits the protection to 167%. That would correspond to a 10 amp breaker. So I would guess that that is the intended answer to the poorly worded question.