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Monday, January 16, 2017
Question:
We have a 100a 3 pole (480v) feeding a UPS. Between the breaker panel and the UPS panel are 2 – 200a fused disconnects. Since the 100a breaker is the actual overcurrent protection device can the fuses in the disconnects be larger? The disconnects themselves were not code required, they exist because the conduit & wire (200a) between them was originally for a different purpose.
John R. Dennis
A
Answer:
Hey John thanks for your question. Yes, conductors are required to be protected in accordance with their ampacity as stated in 240.4. If overcurrent protection is provided there is no prohibition from adding additional overcurrent devices, whether they are larger or not.