Services, Grounding & Bonding第 49 / 120 题
A concrete-encased electrode may be formed by at least 20 feet of which of the following?
a.Bare 4 AWG copper conductor encased in the concrete footing
b.Bare 6 AWG copper conductor encased in the concrete footing
c.Insulated 4 AWG copper conductor run through the footing
d.Bare 8 AWG copper conductor encased in the concrete footing
解析
A concrete-encased electrode consists of at least 20 feet of bare copper not smaller than 4 AWG, or at least 20 feet of one-half inch or larger electrically conductive reinforcing bar, encased in at least 2 inches of concrete near the bottom of a footing in direct contact with earth. Smaller conductors do not qualify, and the copper must be bare so it can couple to the concrete.
法律依据: 2023 NEC §250.52(A)(3)免费刷完整 120 道题库 — 无需注册。
同考点相关题目
- 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 metal underground water pipe qualifies as a grounding electrode only if it is in direct contact with the earth for at least what length?
- 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?
- What is the minimum service disconnecting means rating for a one-family dwelling?