When conductors of a feeder are installed in parallel across multiple raceways, what is the smallest conductor size the NEC generally permits for that parallel arrangement?
Not quite. The answer is A: 1/0 AWG
310.10(G) sets 1/0 AWG copper or aluminum as the smallest conductor size generally permitted to be paralleled, and every parallel set must match in length, material, insulation, and termination method. Paralleling smaller conductors instead of stepping up to one larger conductor is a common design shortcut the code doesn't allow.
Reference: NEC 2023 310.10(G) (Conductors in Parallel)
Checked against multiple published sources
Two trade-press sources place paralleling at 310.10(G) in the 2023 NEC (it was 310.10(H) in 2020 and earlier). Neither is the code text.
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