Question 31
A 50 hp, 480 V three-phase motor is being installed far from the service, and voltage drop is a concern. What design consideration is MOST appropriate?
Question 32
A 120 V branch circuit feeds a 10 A load through 100 ft of copper conductor with a resistance of 0.2 Ω for the round trip. What is the approximate voltage drop?
Question 33
A feeder conductor is run 250 feet to supply a remote panel with a continuous load of 80 amperes at 208 volts, 3 phase. The voltage drop is calculated to be about 6 percent. What is the most appropriate corrective design action?
Question 34
A feeder run to a detached garage is experiencing excessive voltage drop under load. The existing run uses 8 AWG copper conductors at a long distance. Which is the best corrective action?
Question 35
A 120 V, 15 A branch circuit runs 80 feet one way using 14 AWG copper conductors to supply a single receptacle. The load draws 12 A. Which statement best describes the expected voltage at the receptacle?
Question 36
A 240 V, 30 A branch circuit feeds a water heater 80 feet away using copper conductors. What is the purpose of checking voltage drop?
Question 37
A long 120 V branch circuit feeds a sensitive electronic load, and the voltage at the load measures only 110 V at full load. What is the most appropriate corrective measure?
Question 38
A long feeder run experiences nuisance tripping of the upstream breaker during motor starts. Voltage measurements show significant drop during starting. Which design change most directly addresses this issue?
Question 39
A 240 V feeder supplies a remote panel 250 ft away at 40 A. To keep voltage drop within recommended limits, the electrician selects a conductor size that gives about a 3% drop at full load. What is the approximate voltage at the remote panel under full load?
Question 40
A run of 12 AWG copper conductors in a 120 V branch circuit is very long and close to the maximum distance allowed. The load is near the circuit rating. What is a common method to reduce voltage drop?
Question 41
A 120 V branch circuit is 150 ft long to the farthest receptacle. To minimize voltage drop, what is a common field practice?
Question 42
A long 120 V branch circuit feeding a distant receptacle shows excessive voltage drop under load. Which change would most effectively reduce voltage drop without altering the load?
Question 43
When selecting an extension cord for a portable power tool, what is a key safety consideration?
Question 44
A 3-phase, 208 V feeder is 200 ft long supplying a 40 A motor load. The conductors are borderline in size, and the motor has nuisance tripping on start. Which corrective action best addresses voltage drop?
Question 45
A 100 ft run of 12 AWG copper conductor feeds a 120 V, 15 A load. What effect does this length have on the circuit?
Question 46
A 100 ft run of 12 AWG copper conductor on a 20 A, 120 V circuit is causing noticeable dimming when a large load starts. Which action is MOST effective at reducing voltage drop?
Question 47
A $480\text{ V}$, $100 \text{ A}$ three-phase feeder supplies a panelboard that is $125$ feet away. Using the impedance method, the voltage drop is calculated to be $3\%$. What is the resulting voltage drop in volts?
Question 48
A 100 ft run of copper conductor carries 20 A at 120 V. If you are concerned about voltage drop, which action is most effective?
Question 49
A long branch circuit has noticeable voltage drop under load. Which action is most appropriate to reduce the voltage drop?
Question 50
A 480 V, 3-phase motor will be supplied from a 277/480 V system with a 100 ft feeder. The design current is 40 A, and voltage drop must be kept within 3% at the motor terminals. Which consideration is most important when selecting conductor size?
Question 51
A 120 V, 15 A branch circuit feeds receptacles 80 feet away. The voltage drop is a concern. Which change will most effectively reduce voltage drop?
Question 52
Calculate the voltage drop on a 240V single-phase circuit supplying a 30A load using No. 10 AWG copper wire (approx. 1.2 ohms/1000 ft) running 100 feet one way.
Question 53
A 240V motor draws 20A. What is the minimum wire size (copper, THHN) required to keep voltage drop under 3% for a 150 ft run? (K=12.9)
Question 54
A 240V motor draws 25A. If the circuit conductors have a total resistance of 0.4Ω, what is the voltage drop across the conductors?
Question 55
What is the calculated voltage drop of a circuit carrying 20A through 100 feet of 12 AWG solid copper wire (approx 1.93 Ω/1000 ft)? Formula: $V_d = 2 \times K \times L \times I / cmil$. Or simplified $V_d = I \times R$. Total length (hot+neutral) = 200ft.
Question 56
A 120V branch circuit supplies a load drawing 16A. If the circuit length causes a voltage drop of 4%, what is the voltage at the load?
Question 57
Calculate the voltage drop for a 20A load on 100 feet of 12 AWG copper wire (Resistance approx 2 ohms/1000 ft). VD = 2 * L * R * I / 1000.