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Wednesday, June 14, 2023
Question:
Hi Code Question of the Day, I have a contractor installing a 120/208V, 600A, 3-phase service for a new commercial installation. The electrical contractor installed parallel conduits for the service with 4 sets of 500 kcmil aluminum conductors in one conduit and 4 sets of 600 kcmil aluminum conductors in the other conduit. Would this be acceptable or should 310.10(H)(2) be followed? Thanks, Steve Lomison
A
Answer:
Hello Steve. Section 310.10(H)(2)(3) requires that paralleled phased and/or grounded conductors must be the same circular mil area. The information in your question would indicate that there are different wire sizes used for various paralleled conductors which would not be permitted. Additionally, Section 310.10(H)(4) requires the ampacity rating of these paralleled conductors to be adjusted in accordance with Section 310.15(B)(3)(a).