I had a few code related questions in regards to the sizing of cable and equipment on the secondary of 480-208/120V transformer.
1) I know a circuit breaker is required to be close to the secondary of the transformer but what about a case where the main circuit breaker in a panel located on the secondary of the transformer located 95ft away is serving as the secondary protection? Can this breaker in the panel serve as the secondary protection or is this to far away?
2) Can the "next size up" allowance be used between the cable and seconary breaker on a transformer. For instance if the secondary breaker for a 113kVA transformer is sized at 400A can a 500MCM cable rated at 380A be used on the secondary?
On the primary of the transformer
1) Can the transformer be located any distance from the primary breaker in a panel. For instance can it be 100's of feet away? Would another breaker at the transformer be required? Maybe just for disconnecting purposes?
2) If the primary breaker is increaed for inrush then the cable size must also be increased as well to match the breaker? Can the "next size up" rule be used on the primary of the transformer?
1) I know a circuit breaker is required to be close to the secondary of the transformer but what about a case where the main circuit breaker in a panel located on the secondary of the transformer located 95ft away is serving as the secondary protection? Can this breaker in the panel serve as the secondary protection or is this to far away?
2) Can the "next size up" allowance be used between the cable and seconary breaker on a transformer. For instance if the secondary breaker for a 113kVA transformer is sized at 400A can a 500MCM cable rated at 380A be used on the secondary?
On the primary of the transformer
1) Can the transformer be located any distance from the primary breaker in a panel. For instance can it be 100's of feet away? Would another breaker at the transformer be required? Maybe just for disconnecting purposes?
2) If the primary breaker is increaed for inrush then the cable size must also be increased as well to match the breaker? Can the "next size up" rule be used on the primary of the transformer?
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