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Wednesday, May 10, 2023

Question:

Hi CQD. I have a feeder supplied by a 400A circuit breaker in a switchboard. Terminated on the 400A breaker is 4-500kcmil THHN copper conductors running to junction box, where capped off in a junction box. From this junction box, I would like to run a parallel feeder made up of (2) sets of 3/0 THHN copper conductors, to a 400A rated panelboard on the 1st floor. Would this installation be code compliant? Thank you, Jason Fox
A

Answer:

Hello Jason, thank you for your question. The installation you are describing would be permitted if all of the requirements for paralleled conductors found in Section 300.3(B)(1) and 310.10(G). The termination device used for making the transition would need to rated for all conductor sizes in use.

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