Services, Grounding & BondingQuestion 32 of 120
A service is supplied by two parallel sets of 250 kcmil copper conductors per phase. What is the minimum size copper grounding electrode conductor?
a.4 AWG
b.2 AWG
c.1/0 AWG
d.3/0 AWG
Explanation
With parallel conductors the equivalent area is the sum of the areas in one phase: 2 x 250 kcmil = 500 kcmil, which falls in the over 350 through 600 kcmil row and requires 1/0 copper. Using 2 AWG treats a single 250 kcmil conductor as the whole service, and 3/0 corresponds to services above 1,100 kcmil.
Law Reference: 2023 NEC Table 250.66Practice all 120 questions free — no signup required.
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