on Aug 29, 2017A 3 phase, 75kVA, 480V to 208Y/120V, dry-type transformer is protected by a 100A, inverse-time circuit breaker on the primary side of the transformer. What is the maximum rating of the OCPD required to protect the secondary windings of the transformer?
300A OCPD [ NEC 240.4(F) ]
Table 450.3(B) … not to exceed 167% (not the commonly mis-used "next size up") ---> "(See Note 1.)" is not included.