Services & DistributionQuestion 75 of 521
When conductors are installed in parallel, the paralleled conductors of each phase, neutral, or grounded circuit conductor must:
a.Be different lengths to balance impedance
b.Be the same length, same conductor material, same size, and have the same insulation type and termination
c.Use different sizes in each raceway
d.Only match in the ungrounded conductors
Explanation
Per 310.10(G)(1), all parallel conductors of the same circuit designation must be the same length, material, cross-sectional area (size), and insulation, and terminate the same way, so current divides evenly. Different lengths or sizes cause unequal current sharing and overheating.
Law Reference: 2023 NEC §310.10(G)Practice all 521 questions free — no signup required.
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