But, there is no reason to protect the primary at 100 A
which is the largest size fuse that does not exceed 112 A
If the fuses are sized at 110 A, then the wire must b(
rated for 110 A. In this example, find a copper THWl'
wire from NEC Table 310-16 which is rated for at leas
45 A. No. 8 AWG copper THWN wire is rated at 50 A
Therefore, install 50-A fuses in the 480-V panel board
The disconnect switch in Figure 14-28 must be located so that the wire from the transformer is not more
than 25 ft (7 .62 m) in length, NEC Section 240-21, Exception No. 8. This tap conductor must have an amperrating sufficient to supply the load; in this case, at leas
100 A. It must end at a circuit breaker or set of fuse
with a rating not greater than the ampere rating of the ta
conductor. The tap conductor must be enclosed in race
way.