I am replacing a couple of panelboards for a customer that are supplied from a 30kVA UPS. The UPS is a single enclosure with rectifier/charger, inverter and static switch. The input is 480VAC 3 phase with a 120VAC single phase output. There is no output breaker on the load side of the static switch but there is a 400AT MCCB on the inverter side of the S/S. There are two sets of conductors running from the output terminals to the existing two panelboards. Both sets of conductors are 4/0AWG in conduit. The distance from the UPS to the panels is about 20 ft. Both panels have main breakers at 225A each. The panels and UPS are all in the same building.
The question I have is this - The client wants to replace the breaker panels with 100A fused panels each having a 100A main breaker. The 100A main breakers will not accept 4/0 AWG conductors. I am considering using 1/0 AWG conductors. Could NEC 240.21(B)(2) "Feeder Taps" be utilized to justify both the existing installation and the proposed new installation?
The question I have is this - The client wants to replace the breaker panels with 100A fused panels each having a 100A main breaker. The 100A main breakers will not accept 4/0 AWG conductors. I am considering using 1/0 AWG conductors. Could NEC 240.21(B)(2) "Feeder Taps" be utilized to justify both the existing installation and the proposed new installation?