Question 1
A long 120 V branch circuit to a detached garage causes lights to dim noticeably when a large tool starts. Which is the MOST likely cause?
Question 2
To reduce voltage drop on a long branch circuit run, which design choice is most effective?
Question 3
A small workshop has a calculated demand load of 18 kVA at 240 V single-phase. The electrician is selecting a feeder. Which factor, in addition to ampacity, is most important to evaluate when the feeder length is 60 m?
Question 4
A long 120 V branch circuit has a measured voltage drop of 11 V at full load. What is the approximate percentage voltage drop, and why might this be a concern?
Question 5
A feeder shows significant voltage drop under heavy load, causing motor contactors to chatter. Which corrective action is most appropriate?
Question 6
A master electrician is evaluating voltage drop on a long feeder supplying sensitive electronic equipment. Besides upsizing conductors, which design strategy can help reduce total voltage drop to acceptable levels?
Question 7
An apprentice is asked to calculate approximate voltage drop on a long feeder. Increasing conductor size will have what effect on voltage drop?
Question 8
A long 120 V branch circuit feeds receptacles in a distant room. Under load, the voltage measured at the farthest receptacle is noticeably lower than 120 V. Which action is most appropriate to reduce voltage drop?
Question 9
Which measure is most effective at reducing voltage drop on a long feeder circuit?
Question 10
A conduit run on a drawing is dimensioned at 100 ft, supplying a continuous load of 30 A at 120 V with copper conductors. Voltage drop is a concern. What general practice can help minimize voltage drop?
Question 11
A 120 V branch circuit feeds a receptacle that is 150 ft from the panel. To minimize voltage drop, which strategy is MOST appropriate?
Question 12
A long 120 V branch circuit feeds a receptacle 200 ft from the panel. The circuit uses 12 AWG copper, and the load is 16 A continuous. If voltage drop is excessive, what is the MOST appropriate corrective action?
Question 13
A 120 V, 20 A branch circuit is 150 feet long and supplies a continuous load of 16 A. The voltage drop is excessive. Which combination is the most appropriate correction?
Question 14
A long 120 V feeder run to a detached workshop results in noticeable dimming of lights when large tools start. Measurements show voltage at the workshop panel dropping to about 108 V under heavy load while the service voltage at the house remains close to 120 V. Which corrective action is MOST effective to reduce the voltage drop at the workshop?
Question 15
You are asked to lay out branch circuits in an open office to minimize voltage drop and maintain balanced panel loading. What design approach is most appropriate?
Question 16
On a long 120 V branch circuit feeding a workshop, the lights noticeably dim whenever a large portable table saw starts. Which corrective action is most likely to reduce the voltage drop and dimming?
Question 17
You are asked to calculate the approximate voltage drop on a 120 V, 20 A branch circuit feeding a 16 A load located far from the panel. Why might you choose to increase the conductor size from 12 AWG to 10 AWG?