Question 31
A 20 A breaker trips immediately each time a certain receptacle circuit is energized, even with no loads plugged in. What is the MOST likely cause?
Question 32
Which of the following best describes a GFCI device?
Question 33
Which statement best describes an AFCI device?
Question 34
A ceiling light does not work. An apprentice verifies 120 V from hot to ground at the light box, and the lamp and switch are known to be good. Which condition is most likely the cause?
Question 35
A homeowner reports that a breaker trips whenever a portable space heater and a vacuum cleaner are run from the same receptacle. What is the most likely cause?
Question 36
In a dwelling, an AFCI breaker trips intermittently when a vacuum cleaner is used on a bedroom circuit. After confirming the vacuum is in good condition, what should the electrician investigate next?
Question 37
Which protective device is primarily intended to protect the conductors and equipment from **overloads** and **short circuits**?
Question 38
When troubleshooting a continuous ground fault that is tripping a main breaker, which of the following is the safest and most efficient first step, after proper LOTO?
Question 39
Which of the following is the most likely cause of nuisance tripping of a Ground-Fault Circuit Interrupter (GFCI) in a bathroom circuit with no actual ground fault?
Question 40
When troubleshooting a circuit that is only protected by a standard thermal-magnetic circuit breaker, which type of fault is the breaker LEAST likely to clear reliably?
Question 41
What is the primary purpose of a ground-fault circuit interrupter (GFCI) device?
Question 42
An apartment tenant reports that a 15 A breaker has tripped. As a first step, what should the electrician do?
Question 43
What does the number '20' on a single-pole circuit breaker in a residential panel most directly indicate?
Question 44
An electrician is troubleshooting a motor that occasionally trips its overloads but not the circuit breaker. What does this MOST likely indicate?
Question 45
Which of the following devices is designed to protect people from electric shock in wet or damp locations?
Question 46
You are troubleshooting a lighting circuit where the breaker is not tripped, but none of the lights work. A non-contact tester shows no voltage at the switch. What is the next logical step?
Question 47
In a large open office, a new cubicle layout significantly increases the number of workstations on one existing 20 A circuit. Employees report frequent breaker trips. What is the most appropriate long-term solution?
Question 48
A homeowner plugs a space heater and a hair dryer into the same 15 A bathroom circuit, and the breaker trips. What is the most likely cause?
Question 49
A motor circuit uses both a breaker and a thermal overload relay. Which statement best describes the coordination between these devices?
Question 50
Which device is designed to protect people from electric shock caused by ground-faults?
Question 51
On a 120/240 V single-phase service, a residence experiences bright lights on one leg and dim lights on the other. What is the most likely cause?
Question 52
A circuit breaker trips immediately upon being reset. Resistance to ground is 0 ohms. What is the fault type?
Question 53
When troubleshooting a tripped AFCI breaker, what is a common cause of nuisance tripping?
Question 54
If a breaker trips after running for 10 minutes, what is the likely cause?
Question 55
A circuit breaker trips immediately upon closing. You verify there are no short circuits to ground. What is another possible cause?
Question 56
When troubleshooting a tripped circuit breaker, what should be done before resetting it?
Question 57
If a circuit breaker trips immediately upon resetting, what is the most likely fault?