Section 450.3(B) covers the protection of the transformer windings, not the conductors supplying or leaving the transformer. For currents of 9A or more, Sec. 450.3(B), Note 1 applies. Where 125% of ...

The Wye service transformer has three 120-V windings, which are 120 degrees apart. The names come from the secondary winding configuration, which looks like a “Y” or three-sided star (Figure 1). For ...