Services & DistributionQuestion 37 of 110
Service phase conductors total 1,500 kcmil Cu per phase (over 1,100 kcmil). Using the 12.5% rule, what is the minimum copper main bonding jumper?
a.4/0 AWG
b.3/0 AWG
c.250 kcmil
d.2/0 AWG
Explanation
Above 1,100 kcmil, the main bonding jumper is at least 12.5% of the phase area: 0.125 x 1,500 = 187.5 kcmil, so 4/0 Cu (211.6 kcmil) is the smallest that qualifies.
Law Reference: 2023 NEC 250.28(D)Practice all 110 questions free — no signup required.
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