Services & DistributionCâu 55 / 110
A concrete-encased electrode (Ufer) must consist of at least how many feet of #4 or larger rebar or bare #4 Cu conductor?
a.10 ft
b.15 ft
c.20 ft
d.25 ft
Giải thích
A concrete-encased electrode requires at least 20 ft of 1/2-in (or larger) rebar or 20 ft of bare #4 Cu encased in the concrete footing/foundation.
Trích dẫn luật: 2023 NEC 250.52(A)(3)Luyện miễn phí toàn bộ 110 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- A legally required standby system must supply its loads within what maximum time after loss of normal power?
- Generator output conductors must have an ampacity of at least what percent of the nameplate current?
- A feeder supplies a 60,000-VA, 208-V, three-phase load. What is the calculated feeder current?
- A 200-A busbar has a 200-A main breaker at one end. Using the 120% rule, what is the maximum back-fed inverter (PV) overcurrent device at the opposite end?
- A single made electrode (ground rod) must be supplemented unless its resistance to earth does not exceed what value?
- A metal underground water pipe qualifies as a grounding electrode if it is in direct contact with earth for at least how many feet?
Cập nhật gần nhất: · quy trình kiểm tra
Đội Ngũ Biên Tập PrepPass · Đối chiếu với Master Electrician Licensing Exam (NEC-based) · Quy trình kiểm tra