Services, Grounding & BondingCâu 48 / 120
A metal underground water pipe qualifies as a grounding electrode only if it is in direct contact with the earth for at least what length?
a.20 feet
b.10 feet
c.8 feet
d.5 feet
Giải thích
The metal underground water pipe electrode must have 10 feet or more in direct contact with the earth, including any metal well casing bonded to it. The 20-foot value belongs to the concrete-encased electrode, and 5 or 8 feet do not meet the requirement.
Trích dẫn luật: 2023 NEC §250.52(A)(1)Luyện miễn phí toàn bộ 120 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- What is the minimum length of a rod-type grounding electrode?
- Where two rod electrodes are installed to make up the grounding electrode system, what is the minimum spacing between them?
- 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 concrete-encased electrode may be formed by at least 20 feet of which of the following?
- When a metal underground water pipe is used as a grounding electrode, what else is required?
- What is the maximum number of service disconnecting means permitted for a single set of service-entrance conductors?
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