Licensed Electrical Contractor Troubleshooting & Maintenance 2

Question 1

A motor repeatedly trips its overload relay shortly after reset. What is the most likely cause?

Accepted Answer

Motor running in a high-resistance fault condition

Answer

Overload relay set too low

Answer

Incorrect phase rotation

Answer

Loose terminal at the motor disconnect

Question 2

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?

Accepted Answer

Normal balanced current flow

Answer

An open circuit on the load side

Answer

A ground fault on the circuit

Answer

A high-resistance connection

Question 3

A GFCI outlet tests correctly but will not reset. The most likely cause is:

Accepted Answer

A downstream ground fault is still present

Answer

The GFCI module is wired line-to-load reversed

Answer

The circuit breaker is undersized

Answer

Neutral-to-ground bond is missing at the panel

Question 4

During a megohmmeter test on a cable, the insulation resistance reads near zero. The best next step is to:

Accepted Answer

Disconnect all equipment and retest the cable alone

Answer

Replace the entire cable run immediately

Answer

Increase test voltage to obtain a more accurate reading

Answer

Apply dielectric grease to the conductors

Question 5

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?

Accepted Answer

Voltage unbalance on the supply

Answer

Incorrect overload heater size

Answer

Open delta transformer bank

Answer

Motor winding shorted turn

Question 6

An arc-fault circuit interrupter (AFCI) breaker is tripping on a bedroom circuit. Which tool helps identify the cause?

Accepted Answer

Receptacle tester with arc-fault indicator

Answer

Megohmeter at 1000V

Answer

Clamp meter measuring neutral current

Answer

Voltage drop tester across each outlet

Question 7

What is the purpose of performing a 'wiggle test' on electrical connections during maintenance?

Accepted Answer

To identify loose or intermittent connections that cause heating

Answer

To verify torque on all lugs meets spec

Answer

To test insulation flexibility in cold environments

Answer

To check for conductor corrosion under insulation