90 amperes

What Size Wire Do I Need To Feed A 45 KVA Transformer? For a 45kVA transformer, 54A×1.25=68A, so use a 4 AWG conductor rated 85A at 75°C, per Table 310.16. What size breaker do I need for a 45 kva transformer? A 45 KVA transformer protected on the supply side with a 70-ampere circuit breaker