Question 91
When stripping insulation from a small copper conductor, which practice helps prevent damage to the wire?
Question 92
A 480 V three-phase motor is connected in a delta configuration. Which line-to-line voltage does each winding see?
Question 93
During troubleshooting, you find that a control relay coil is rated 24 V AC but is connected across 120 V AC control power. Which outcome is most likely?
Question 94
Before starting work on an electrical circuit, what is the first step an apprentice should take?
Question 95
When troubleshooting a motor that will not start, the electrician measures full line voltage at the motor terminals while the starter is energized, but the motor shaft does not move. What is the next logical check?
Question 96
A three-phase 30 hp motor operates on a 480 V system. During startup, the lights in the building dim significantly. Which mitigation strategy is most appropriate?
Question 97
When reviewing a motor nameplate, which value is most important for selecting the correct overload relay setting?
Question 98
A large motor is started across-the-line and causes noticeable voltage dip and lights dimming in the facility. The engineer proposes a reduced-voltage starting method. What is one common benefit of using reduced-voltage starting for this motor?
Question 99
Which device is commonly used to safely de-energize a motor for maintenance?
Question 100
During commissioning, a facility with multiple motor loads experiences lights dimming significantly when large motors start. What is the most appropriate approach to address this issue?
Question 101
A relay used in a motor control circuit has a coil rated at 120 V. What happens if the coil is only supplied with 60 V?
Question 102
A large rooftop HVAC unit is fed by a long conduit run. The motor occasionally fails to start, and your measurements show significant voltage drop at the unit only during starting. Which corrective action is MOST effective?
Question 103
Several LED light fixtures in an office briefly dim whenever a large motor starts in the same building. What is the most likely cause?
Question 104
A 120 V circuit supplies a load at the end of a long run of wire. The total resistance of the supply conductors is 1 Ω and the load resistance is 11 Ω. What voltage will appear across the load when the circuit is energized?
Question 105
A single-phase motor on a rooftop unit hums but does not start when energized. The supply voltage is correct, and the breaker does not trip. What is the MOST likely cause?
Question 106
A motor fails to start and only hums when energized. Which is a likely electrical cause?
Question 107
In a control circuit, why are control transformers often used to supply 24 V control power for contactor coils?
Question 108
When reading a scaled electrical floor plan, what should you do FIRST to understand actual distances between devices?
Question 109
Which condition is most likely to cause nuisance tripping of a standard circuit breaker on a motor circuit during starting?
Question 110
A three-phase motor is nameplated at 10 hp, 480 V, 3-phase, and has a full-load current (FLC) of 14 A. If the motor is started across the line, what is a reasonable expectation of inrush current during starting?
Question 111
You are troubleshooting a lighting circuit controlled by a single-pole switch. The lights will not turn on. You measure 120 V from the supply hot to neutral on the line side of the switch, but 0 V on the load side when the switch is on. What is the most likely issue?
Question 112
A straight wall in a living room is 25 ft long. Receptacle outlets must be placed so that no point along the wall line is more than 6 ft from a receptacle. What is the minimum number of receptacle outlets required on this wall?
Question 113
A three-phase motor on a conveyor will not start. The control circuit indicator light is on, the start button is working, and full line voltage is measured at the line terminals of the contactor. However, there is no voltage at the motor terminals when the start button is pressed. Which issue is most likely?
Question 114
Parking lot lights are controlled by a contactor coil that is fed through both a photocell and a manual override switch. The lights remain on all day, and voltage is present at the coil even when the photocell should be open and the switch is off. Which wiring error is most likely?
Question 115
When preparing to replace a 120 V receptacle in a residence, what should the electrician do first?
Question 116
A digital multimeter set to measure voltage is placed across the hot and neutral of a receptacle. What should the meter leads be connected to?
Question 117
You are troubleshooting a three-phase motor that will not start. The control circuit appears intact, but the motor only hums when energized. Which is the most likely first test to perform?
Question 118
Which document should a journeyperson consult first to understand site-specific safety rules and procedures before starting work on a new commercial project?
Question 119
Which tool is best suited for removing insulation from a copper conductor without damaging the wire strands?
Question 120
When using a digital multimeter to troubleshoot an unknown circuit, which practice is safest?