Mạch nhánh & Đi dâyCâu 230 / 521
The circuit in the previous scenario has a voltage drop of about 6.6%, well above the recommended 3% for a branch circuit. What is the most appropriate corrective action?
a.Leave it; 6.6% is acceptable
b.Increase the conductor size to reduce voltage drop
c.Increase the breaker size to 30 A
d.Add a second ground rod
Giải thích
Increasing the conductor cross-sectional area (more circular mils) lowers the voltage drop, since VD is inversely proportional to cmil. Raising the breaker size does not reduce voltage drop (and may violate conductor ampacity), and grounding changes do not affect voltage drop.
Luyện miễn phí toàn bộ 521 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- The NEC informational note recommends that voltage drop on a branch circuit not exceed what percentage of the circuit voltage?
- For the combined feeder plus branch circuit, the NEC informational note recommends total voltage drop not exceed what percentage?
- A 120 V single-phase circuit uses 12 AWG copper (6,530 cmil) carrying 20 A over a one-way length of 100 ft. Using VD = 2 × K × I × L ÷ cmil with K = 12.9, what is the approximate voltage drop?
- A 240 V single-phase circuit uses 10 AWG copper (10,380 cmil) carrying 24 A over a one-way length of 150 ft, with K = 12.9. What is the approximate voltage drop and percentage?
- In the voltage-drop formula for a balanced 3-phase circuit, which multiplier replaces the factor of 2 used in single-phase calculations?
- To reduce voltage drop on a long branch-circuit run without changing the load, what is the most effective method?
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