Branch Circuits & WiringQuestion 202 of 521
Per Table 310.15(C)(1), what adjustment factor applies when there are 4 to 6 current-carrying conductors in a raceway?
a.70%
b.80%
c.60%
d.50%
Explanation
The table assigns 80% for 4–6 current-carrying conductors. 70% is for 7–9, 50% is for 10–20, and 60% is not a listed factor.
Law Reference: 2023 NEC §310.15(C)(1)Practice all 521 questions free — no signup required.
Related questions on this topic
- Given a 40% usable fill area of 0.213 in² (3/4" EMT) and a 12 AWG THHN cross-sectional area of 0.0133 in² (Table 5), how many 12 AWG THHN conductors fit?
- Six current-carrying 12 AWG THHN conductors (90°C, 30 A base) share a raceway. Applying only the adjustment factor for 4–6 conductors, what is the adjusted ampacity?
- Per Table 310.15(C)(1), what adjustment (derating) factor applies when there are 7 to 9 current-carrying conductors in a raceway?
- Per Table 310.15(C)(1), what adjustment factor applies when there are 10 to 20 current-carrying conductors in a raceway?
- In a 3-wire, single-phase circuit (two hots and a neutral), how is the neutral treated when counting current-carrying conductors for adjustment?
- In a 4-wire, 3-phase wye circuit supplying nonlinear (harmonic-producing) loads, how is the neutral treated for conductor-count adjustment?
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