Licensed Electrical Contractor Troubleshooting & Maintenance 5

Question 1

An electrician is performing a continuity test on a 3-conductor cable and gets a reading between the black and white conductors. This indicates:

Accepted Answer

A short circuit between the conductors — the cable must be replaced

Answer

Continuity between black and white conductors in a de-energized cable indicates an insulation failure or direct short that requires cable replacement.

Question 2

During routine maintenance, a licensed electrician discovers that aluminum conductors are connected to a CO/ALR-rated receptacle using push-in (backstab) terminals. The correct action is to:

Accepted Answer

Rewire to the screw terminals — backstab terminals are not rated for aluminum conductors

Answer

CO/ALR receptacles permit aluminum connections only via screw terminals, not push-in backstab connections, which are unreliable with aluminum.

Question 3

A variable frequency drive (VFD) repeatedly faults on 'output phase loss.' The motor and cabling test good. Where should the electrician look next?

Accepted Answer

Output contactor or terminal connections between VFD and motor

Answer

If the motor and cable test good, the output phase loss fault usually points to a loose connection or failed output contactor between the VFD and motor.

Question 4

A ground fault indicator on a 480V delta system is glowing on one phase. What does this indicate?

Accepted Answer

A ground fault on that phase, changing voltage relationships to ground

Answer

On an ungrounded delta system, a single ground fault causes the affected phase to read near zero to ground while the other two glow bright on indicator lights.

Question 5

An electrician is troubleshooting a lighting system where half the fixtures in a series of fluorescent fixtures are out. The most efficient first step is to:

Accepted Answer

Check voltage at the first dead fixture to determine if power is present

Answer

Checking voltage at the first dead fixture identifies whether the problem is upstream (no power) or within the fixtures themselves, guiding all subsequent steps.

Licensed Electrical Contractor Practice Test

Licensed Electrical Contractor Practice Test

Licensed Electrical Contractor Troubleshooting & Maintenance 5