Question 1
You are troubleshooting a lighting circuit where the lamps glow very dimly. A quick check shows 60 V between hot and neutral at the lampholder instead of 120 V. Which is the most likely cause?
Question 2
You measure 120 V at a receptacle with no load. When a portable heater is plugged in, the voltage drops to 106 V and the cord gets warm. What is the most likely issue?
Question 3
You are reviewing a specification that requires a maximum allowable voltage drop of 3% on branch circuits at the farthest outlet. If a 120 V circuit measures 110 V at the farthest receptacle under full load, what should you conclude?
Question 4
A 30 m long 120 V branch circuit supplies a 12 A load. If the conductor resistance causes a 3 percent voltage drop at full load, approximately what is the voltage at the load end?
Question 5
In a high-rise building, a feeder supplies several panelboards at different floors. How should voltage drop be addressed in the design?
Question 6
What is the effect of a loose neutral connection in a 3-wire, single-phase 120/240V system?
Question 7
What is the primary hazard of a high-resistance connection in a high-current circuit?
Question 8
What is the effect of a loose neutral connection in a 3-wire 120/240V system?
Question 9
A 120 V circuit is supplying a load at the end of a 30 m run of #14 AWG copper. The load current is 12 A. What effect does voltage drop have on the load?
Question 10
An electrician is asked to run a long feeder to a detached garage. Which factor is most important to consider to minimize voltage drop?
Question 11
A 30 m run of cable supplies a 16 A load at 120 V. If the conductor resistance causes a small but noticeable voltage drop, what is the most appropriate action during design?
Question 12
An electrician is troubleshooting a lighting circuit where the breaker is on, but none of the lights operate. The voltage tester shows 120 V between hot and neutral at the panel, but 0 V at the first switch box. Which is the MOST likely problem?
Question 13
During troubleshooting, an electrician finds a loose neutral connection in a multiwire branch circuit feeding two small-appliance circuits in a kitchen. What type of problem can this loose neutral cause?
Question 14
A long 120-volt branch circuit feeds receptacles 200 feet from the panel. Equipment operates but voltage at the farthest receptacle measures only 110 volts under load. What design issue is most likely responsible?
Question 15
You measure 120 V between hot and neutral at a receptacle, but a plugged-in lamp does not turn on. What is the BEST next step?
Question 16
A receptacle circuit in a dwelling repeatedly shows discolored insulation and warm connections at one device. What is the most likely cause?
Question 17
A long 120 V branch circuit to an outbuilding shows noticeable dimming of lights when a heater turns on. What is the most likely issue?
Question 18
A large office floor has multiple lighting circuits fed from one panel. Several fixtures on different circuits are flickering slightly whenever a large copier runs. Which issue is most likely?
Question 19
A 100 ft run of 12 AWG copper conductor on a 20 A, 120 V circuit will have some voltage drop. Which factor increases voltage drop the most?
Question 20
Several lights on a long branch circuit dim noticeably whenever a large motor starts. What is the most likely cause?
Question 21
A receptacle feels warm to the touch and occasionally causes a crackling sound when a load is plugged in. What is the most likely cause?
Question 22
A dimming issue is reported on a bank of LED troffers controlled by an electronic dimmer. The lights flicker and do not dim smoothly. All connections are tight. What is the MOST likely cause?
Question 23
Which of the following is a symptom of a loose neutral connection in a 120/240V residential service?
Question 24
When troubleshooting a 240V electric heater that isn't working, you measure 120V from L1 to Ground and 120V from L2 to Ground, but 0V from L1 to L2. What is the problem?
Question 25
What is the primary hazard of a 'shared neutral' (multi-wire branch circuit) if the neutral is opened/disconnected while the circuit is energized?
Question 26
You find a breaker that is hot to the touch but has not tripped. The current load is 50% of the rating. What is a likely cause?