Branch Circuits & WiringQuestion 232 of 521
In the voltage-drop formula for a balanced 3-phase circuit, which multiplier replaces the factor of 2 used in single-phase calculations?
a.2
b.1
c.3
d.1.732
Explanation
Three-phase voltage drop uses 1.732 (the square root of 3) in place of the single-phase factor of 2. Using 2 would be the single-phase form, and 1 or 3 are incorrect multipliers.
Practice all 521 questions free — no signup required.
Related questions on this topic
- 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?
- 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 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?
- To reduce voltage drop on a long branch-circuit run without changing the load, what is the most effective method?
- If the one-way length of a circuit run is doubled while current and conductor size stay the same, what happens to the voltage drop?
- Per 200.6(A), a grounded (neutral) conductor 6 AWG or smaller must be identified by which of the following?
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against California CSLB C-10 Electrical Trade Examination · How we review