Parallel Conductor Ampacity
Total ampacity of N paralleled conductor sets with the NEC more-than-three current-carrying-conductor and ambient adjustments, plus per-set load adequacy (1/0 AWG and larger only).
Formula and source
I_total = I_single x N x F_ccc x F_ambient, where N is the number of identical parallel sets, F_ccc is the more-than-three current-carrying-conductor adjustment (1.0 for <=3, 0.8 for 4-6, 0.7 for 7-9, 0.5 for 10-20, ...), and F_ambient the temperature correction. Per-set current I_set = I_load / N. Paralleling is permitted only at 1/0 AWG and larger.
NEC (NFPA 70) Article 310 paralleled-conductor provisions and the 310.15(C)(1) adjustment factors, by name.
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