Using paragraph (c) of Rule 14-100, can the conductor supplying a fusible switch be rated lower that the switch rating?

Yes, provided the conductor is rated at least equal to or above the rating of the overcurrent device installed and has an ampacity not less than 1/3 of the conductor from which the switch is supplied.

(c) Where the smaller conductor:
(i) Has an ampacity not less than one-third that of the larger conductor from which it is supplied; and
(ii) Is suitably protected from mechanical damage, is not more than 7.5 m long, and terminates in a single overcurrent device rated or set at a value not exceeding the ampacity of the conductor, but beyond the single overcurrent device the conductor shall be permitted to supply any number of overcurrent devices.

Tony Moscioni
Electrical Inspector
Electrical Safety Authority