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These 10 free DE-ME questions are organized by exam domain, so you can see how each part of the Delaware Master Electrician License Exam blueprint is tested. Reveal the answer and explanation under each question.
Domain 1: General Electrical Knowledge
Question 1
Two 120 V loads share the neutral of a 120/240 V multiwire branch circuit. An electrician records 120 V from each leg to neutral at the source, but 82 V and 158 V at the two loads; voltage between the ungrounded conductors remains 240 V. The load voltages move in opposite directions as the loads change. After safely isolating the circuit, the electrician should investigate which fault first?
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Correct answer: C - An open or high-resistance connection in the shared neutral
Question 2
A 208Y/120 V feeder supplies office computers and other nonlinear single-phase loads. True-RMS measurements are 54 A, 55 A, and 54 A on the phases, but 78 A on the neutral. Power-quality analysis confirms that the fundamental-frequency components are balanced. Which explanation accounts for the substantial neutral current despite nearly equal phase readings?
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Correct answer: A - Triplen harmonic components from the loads can reinforce one another in the neutral.
Domain 2: Plan Reading
Question 3
The one-line for an existing shop shows a 240/120 V, three-phase, four-wire high-leg delta system, with phase B identified in orange. Four proposed connections appear on the panel schedule. Breaker voltage ratings and all other circuit provisions are suitable for their assigned connections. Which schedule entry requires revision?
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Correct answer: D - 120 V lighting circuit connected from phase B to neutral
Domain 3: Equipment for General Use
Question 4
A condensing unit is marked 'Minimum Circuit Ampacity: 28 A' and 'Maximum Circuit Breaker: 45 A.' The proposed circuit has 10 AWG copper conductors with a final allowable ampacity of 30 A after all applicable limits, a 45 A breaker, and the unit's listed overload protection. Which review comment correctly applies the 2020 NEC to this conductor-and-breaker selection?
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Correct answer: A - Accept; the conductors and breaker meet their respective nameplate limits.
Domain 4: Wiring & Protection
Question 5
An older garage has a worn two-slot receptacle in a nonmetallic box supplied by two-wire cable with no equipment grounding conductor or GFCI protection. No connected equipment requires an equipment grounding conductor, and all other applicable protection requirements are satisfied. The owner requests a three-slot replacement without rewiring the circuit. Which method is permitted by the 2020 NEC?
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Correct answer: B - Install a GFCI receptacle marked 'No Equipment Ground,' with its grounding terminal unconnected.
Question 6
The optional dwelling calculation in the 2020 NEC is being used for a qualifying 120/240 V, single-phase, 200 A service. The general-load subtotal is 32,000 VA, excluding heating and cooling. Three separately controlled resistance-heating units total 12,000 W; air-conditioning nameplate load is 7,000 VA. Controls prevent heating and cooling from operating together. What total calculated load results?
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Correct answer: B - 26,600 VA
Domain 5: Wiring Methods & Materials
Question 7
Eight current-carrying 10 AWG copper THWN-2 conductors share a 60 ft raceway at 43°C. Terminations are rated 75°C. The 2020 NEC ampacities for this conductor are 30 A at 60°C, 35 A at 75°C, and 40 A at 90°C; the applicable conductor-count and 90°C ambient factors are 0.70 and 0.87. One circuit will carry a 26 A noncontinuous load. Which ampacity finding governs its review?
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Correct answer: C - 24.36 A; the conductor cannot carry the proposed load.
Question 8
Three 12/2-with-ground cables enter a box containing one duplex receptacle on one yoke and internal cable clamps. The receptacle is connected with 12 AWG insulated pigtails that begin and end entirely inside the box. While preparing the 2020 NEC box-fill worksheet, which entry should the electrician use?
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Correct answer: D - One conductor-volume allowance for all the internal cable clamps together.
Domain 6: Motors & Controls
Question 9
For a continuous-duty 10 hp, 230 V, three-phase motor, the NEC table full-load current is 28 A. Its nameplate shows 24 A, a service factor of 1.20, and a temperature rise of 50°C. A separate overload device is being selected under the 2020 NEC, with no increase needed to start or carry the load. What is the maximum initial overload-device current rating?
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Correct answer: B - 30.0 A
Domain 8: Special Equipment
Question 10
At a new permanently installed fiberglass pool, the contractor documents compliant perimeter and metal-part bonding. The only bonded component touching the water is a corrosion-resistant fitting with 6 square inches of conductive contact, connected with 8 AWG solid copper. The pump's equipment grounding conductor and GFCI have passed their checks. Under the 2020 NEC, what correction is still needed?
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Correct answer: C - Provide a bonded water-contact surface of at least 9 square inches.