10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
The TN-EC exam has 100 questions and runs 5 hours.
These 10 free TN-EC questions are organized by exam domain, so you can see how each part of the Tennessee Electrical (CE) Contractor Examination blueprint is tested. Reveal the answer and explanation under each question.
At a 120/240 V, three-phase, four-wire delta panel, an electrician measures 120 V from phases A and C to neutral and approximately 208 V from phase B to neutral. What is the correct interpretation?
Correct answer: B - The readings are normal; identify the B-phase high leg orange at connection points
On a floor plan marked 1/8 in = 1 ft, a feeder route measures 5.5 in, which scales to 44 ft. The same route has a written dimension of 46 ft, and no later revision or detail supersedes it. What length should control the takeoff before adding vertical rise and waste?
Correct answer: B - 46 ft, because the written dimension governs the scaled measurement
A contractor is reviewing the branch circuit for a swimming-pool pump motor. Article 430 addresses the motor circuit, while Article 680 contains pool-specific requirements. How should these provisions be applied?
Correct answer: C - Apply the general motor rules first, then the applicable Article 680 modifications
A 40 ft dry indoor raceway contains six 1 AWG copper THHN conductors that all carry load current. The ambient temperature is 30°C, and the equipment terminations are rated 75°C. Under the 2017 NEC, what is the maximum allowable ampacity of each conductor before applying any load-sizing multiplier?
Correct answer: D - 120 A, by adjusting the 90°C ampacity and then checking the 75°C limit
Copper circuit conductors marked only THHN are installed in buried PVC conduit between a building and a detached sign. A separate equipment grounding conductor is present, and the raceway is sealed at both ends. What change makes the installation compliant?
Correct answer: A - Replace the circuit conductors with THWN-2 or another wet-location-listed type
A 480 V, three-phase motor ran in the correct direction until its contactor was replaced. It now runs in reverse, while all three line-to-line voltages and phase currents remain balanced. How should the original rotation be restored?
Correct answer: A - De-energize, verify absence of voltage, and interchange any two phase conductors
A data cable will be installed exposed in a ceiling space used for environmental air. The available cable types are CMP, CMR, CM, and CMX. The acceptable installation is to:
Correct answer: D - Install CMP, or place another permitted cable in a raceway allowed in the plenum
In a wet procedure location supplied by an isolated power system, the line isolation monitor displays 6.2 mA total hazard current and alarms. The procedure equipment remains energized. The most accurate interpretation is:
Correct answer: C - Isolation has degraded above the alarm threshold; locate the fault without assuming the monitor opened the circuit
A powder-transfer room produces ignitable airborne aluminum dust during normal material handling. Which hazardous-location classification best fits the described condition?
Correct answer: A - Class II, Division 1, Group E
A qualified electrician must replace lugs inside a 480Y/277 V panel. Production can be shut down without creating an additional hazard. What must be completed before work begins?
Correct answer: D - Identify and isolate every source, apply lockout/tagout, test phase-to-phase and phase-to-ground, and prove the tester on a known live source before and after the absence test
The TN-EC exam also covers these domains. Drill them in the full free practice test:
The full bank has 1,020 more TN-EC questions with explanations.
Continue in the free practice test →
View plans