MIFOTRA Electrical and Electronics

What this course covers

• Electrical Circuits
• Electronics & Automation
• Maintenance

Practice exam

45 questions, 75 minutes. Answers and explanations appear as you go.

Browse these questions

• A technician is running a new 50A branch circuit to a range. They pull 8 AWG THHN copper wire through an attic where the ambient temperature reaches 120°F. During inspection, the installation fails. Why?
• While remodeling a residential bathroom, an apprentice wires a new 20A receptacle directly to the vanity light switch circuit without GFCI protection. What specific code violation has occurred?
• A homeowner complains that a newly installed bedroom outlet trips the breaker whenever a lamp is turned on. The panel has a dual-function AFCI/GFCI breaker. What is the most likely cause?
• During an inspection of a commercial kitchen, you notice the 125V, 15A receptacles near the sinks lack GFCI protection. The manager claims they are exempt because they are dedicated for refrigerators. How should you respond?
• An electrician installs a 100A subpanel in a detached garage using a 3-wire feeder (two hots, one neutral) and bonds the neutral to the ground bus at the subpanel. What is the primary safety risk here?
• A maintenance tech uses a megohmmeter to test a 480V 3-phase pump motor. The reading from phase A to ground is 0.5 MΩ. What should the tech conclude?
• You place a clamp-on ammeter around an extension cord powering a running 12A space heater, but the meter reads 0.00A. What is the reason for this reading?
• A technician measures voltage at a standard 120V receptacle and gets 120V between hot and neutral, but 0V between neutral and ground, and 60V between hot and ground. What is the most likely fault?
• When checking a 3-phase panel, you read 120V from Phase A to Neutral, 120V from Phase B to Neutral, and 208V from Phase C to Neutral. What type of electrical system are you testing?
• An industrial oven keeps tripping its breaker intermittently. A tech checks the amp draw and finds it steady at 38A on a 40A breaker. Why is the breaker tripping?
• You are replacing a 10 HP, 460V, 3-phase motor. The nameplate lists the Full Load Amps (FLA) as 14.0A and the Service Factor as 1.15. What is the maximum setting for the overload relays according to general NEC rules?
• A large induction motor utilizes a star-delta starter to reduce inrush current. During the start sequence, the motor starts in star but trips the main breaker the exact moment it transitions to delta. What is the most likely cause?
• An operator reports that a 3-phase conveyor motor is "humming loudly and getting extremely hot" but not turning. Voltage measurements at the motor peckerhead show 480V between L1-L2, 0V between L2-L3, and 0V between L1-L3. What is happening?
• When wiring a dual-voltage (230/460V) 9-lead 3-phase motor for high voltage (460V), how should the windings be connected?
• A technician is sizing the branch circuit conductors for a single 25 HP, 460V, 3-phase motor with a table FLC of 34A. What is the minimum ampacity required for these conductors?
• A maintenance team replaces the air filters on HVAC rooftop units every three months, regardless of their condition. What type of maintenance strategy is this?
• A facility uses ultrasonic sensors to monitor the high-frequency acoustic emissions of roller bearings on a critical conveyor. When the acoustic signature crosses a threshold, a work order is generated. What strategy is this?
• A technician repairing a failed boiler feed pump decides to analyze why the seal failed. They discover the baseplate is vibrating due to improper grouting, so they regrout the baseplate to prevent future seal failures. What strategy does this represent?
• A technician is troubleshooting a PLC ladder logic program. A physical emergency stop button is wired normally closed (NC) in the field. In the ladder logic, what instruction should be used to allow the machine to run when the E-stop is NOT pressed?
• A PLC controls a pneumatic cylinder. The sequence stops mid-cycle. The technician forces the output bit ON in the PLC software, and the cylinder moves. What does this confirm?

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