Troubleshooting & Maintenance Flashcards
7 cards from real Licensed Electrical Contractor practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Troubleshooting & Maintenance flashcards as text
A motor repeatedly trips its overload relay shortly after reset. What is the most likely cause?
Answer: Motor running in a high-resistance fault condition
A motor tripping overloads repeatedly after reset typically indicates a high-resistance fault (such as a failing winding or bearing friction) drawing excess current.
When using a clamp-on ammeter to troubleshoot a single-phase 240V circuit, you clamp around both conductors and read zero. What does this indicate?
Answer: Normal balanced current flow
Clamping both conductors of a single-phase circuit cancels opposing magnetic fields, resulting in a zero reading, which indicates normal balanced current.
A GFCI outlet tests correctly but will not reset. The most likely cause is:
Answer: A downstream ground fault is still present
A GFCI that trips immediately upon reset indicates a ground fault condition still exists on the circuit or load side.
During a megohmmeter test on a cable, the insulation resistance reads near zero. The best next step is to:
Answer: Disconnect all equipment and retest the cable alone
Disconnecting all equipment isolates whether the low reading is from the cable itself or connected loads before condemning the cable.
A 3-phase motor is running but drawing unequal currents on all three phases. Single-phasing has been ruled out. What is the most likely cause?
Answer: Voltage unbalance on the supply
Even a small supply voltage unbalance causes disproportionately larger current unbalance in a 3-phase motor.
An arc-fault circuit interrupter (AFCI) breaker is tripping on a bedroom circuit. Which tool helps identify the cause?
Answer: Receptacle tester with arc-fault indicator
A receptacle tester with an arc-fault indicator can simulate arcing conditions to help locate the fault on the circuit.
What is the purpose of performing a 'wiggle test' on electrical connections during maintenance?
Answer: To identify loose or intermittent connections that cause heating
Physically wiggling connections while monitoring for voltage changes or sparks identifies loose or intermittent connections before they fail.