Services & DistributionCâu 53 / 110
A single made electrode (ground rod) must be supplemented unless its resistance to earth does not exceed what value?
a.25 ohms
b.5 ohms
c.10 ohms
d.1 ohm
Giải thích
A single rod, pipe, or plate electrode must be supplemented by a second electrode unless it has a resistance to earth of 25 ohms or less.
Trích dẫn luật: 2023 NEC 250.53(A)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 metal underground water pipe qualifies as a grounding electrode if it is in direct contact with earth for at least how many feet?
- A concrete-encased electrode (Ufer) must consist of at least how many feet of #4 or larger rebar or bare #4 Cu conductor?
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