Branch Circuits & WiringQuestion 203 of 521
Per Table 310.15(C)(1), what adjustment factor applies when there are 10 to 20 current-carrying conductors in a raceway?
a.70%
b.80%
c.50%
d.45%
Explanation
The table assigns 50% for 10–20 current-carrying conductors. 80% is for 4–6, 70% is for 7–9, and 45% is for 21–30 conductors.
Law Reference: 2023 NEC §310.15(C)(1)Practice all 521 questions free — no signup required.
Related questions on this topic
- 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 4 to 6 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?
- Is an equipment grounding conductor (EGC) ever counted as a current-carrying conductor when applying conductor-count adjustment factors?
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