Attributes . CAUTION: When using the 120V center tap for single-phase applications, the single-phase load should not exceed 5% of the three-phase kVA rating. Connect the X3 ?high leg? to the ?B? phase per NEC 384- 3 (do not use X3 leg for 120V lighting). A separate single-phase transformer should be used if the single-phase load is in excess of 5%. Fuse input side per current NEC requirements. . Values