Branch Circuits & Feeders第 24 / 120 题
A 200-ampere feeder uses THHN copper conductors, but the equipment terminations are rated 75 degrees C. What is the minimum conductor size?
a.4/0 AWG
b.2/0 AWG
c.3/0 AWG
d.250 kcmil
解析
Because the terminations are listed for 75 degrees C, the final ampacity must be taken from the 75 degrees C column even though THHN is a 90 degrees C insulation. In that column 2/0 copper is 175 A and fails, while 3/0 copper is 200 A and matches the device. Reading the 90 degrees C column would wrongly allow 2/0, and 4/0 or 250 kcmil exceed the minimum.
法律依据: 2023 NEC §110.14(C)(1)(b)免费刷完整 120 道题库 — 无需注册。
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