Standard Size Calculator for Fuses and Circuit Breakers by CTIPR.org Section 240-6(a)
(Size up or down allowed for 800 amperes or less.)
(Size down above 800 amperes)
(1) Size down for conductors that are part of a multioutlet branch-circuit
supplying receptacles for cord and plug connected portable loads.
(2) Additional fuse sizes of 1, 3, 6, 10, and 601 amperes
are not included.
Fuses can be manufactured to almost any size.