Services, Grounding & Bonding第 47 / 120 题
A single ground rod does not have to be supplemented by a second electrode if its resistance to earth does not exceed what value?
a.5 ohms
b.25 ohms
c.100 ohms
d.1 ohm
解析
A single rod, pipe or plate electrode must be supplemented unless it is shown to have a resistance to earth of 25 ohms or less. Values such as 5 ohms or 1 ohm come from specialized standards for communications and lightning systems, not from this general requirement, and 100 ohms is far too high.
法律依据: 2023 NEC §250.53(A)(2)免费刷完整 120 道题库 — 无需注册。
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