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The MD-ME exam has 90 questions and runs 4 hours.
These 10 free MD-ME questions are organized by exam domain, so you can see how each part of the Maryland Master Electrician License Exam blueprint is tested. Reveal the answer and explanation under each question.
In a 120/240-volt, single-phase dwelling, a technician measures 240 volts line-to-line. With several 120-volt loads energized, one leg measures 148 volts to neutral and the other measures 92 volts; with the loads removed, both return close to 120 volts. Which fault best explains the readings?
Correct answer: A - An open or high-resistance service neutral
A clamp ammeter placed around both ungrounded conductors and the grounded conductor of a loaded 120/240-volt feeder reads 0.74 ampere, even though the individual conductor currents are much higher. What does the nonzero residual reading indicate?
Correct answer: C - Some current is returning outside the clamped conductors, such as on a grounding path
A plant adds shunt capacitors at a motor-control center. The mechanical load, real power in kilowatts, and supply voltage remain essentially unchanged, while power factor improves from 0.72 to 0.93. Which feeder change should follow?
Correct answer: B - The feeder current and conductor I²R losses decrease
A 480Y/277-volt panelboard has exposed live parts on the equipment side only. A grounded concrete wall is directly opposite the panel. What minimum working-space depth is required?
Correct answer: D - 3.5 feet, because the grounded wall creates Condition 2
A 50-ampere, 240-volt receptacle in a dwelling basement supplies a welder. The receptacle is on a single-phase circuit rated 120 volts to ground. Under the 2020 NEC, what protection must be provided?
Correct answer: B - GFCI protection for the receptacle
A detached garage is supplied by a four-wire feeder consisting of two ungrounded conductors, an insulated neutral, and an equipment grounding conductor. A grounding electrode system is installed at the garage. Which arrangement is correct at the garage panel?
Correct answer: D - Isolate the neutral; bond the grounding bar and enclosure, and connect the electrode conductor to that bar
A contractor pulls Type NM-B cable through PVC conduit buried between a house and a detached workshop, arguing that the glued conduit keeps the cable dry. What correction is required?
Correct answer: C - Replace the NM-B with conductors or cable listed for wet locations
A 4-inch square, 1.5-inch-deep metal box is marked 21.0 cubic inches. Three 12/2 cables enter. All six insulated 12 AWG conductors are spliced or terminated in the box. One duplex receptacle is mounted on a single yoke and connected with 12 AWG conductors. The box has one internal cable clamp; all equipment grounding conductors are 12 AWG, and their pigtails originate and remain inside. Using 2.25 cubic inches per 12 AWG conductor volume, which conclusion is correct?
Correct answer: A - 22.5 cubic inches is required, so the 21.0-cubic-inch box is too small
A listed condensing unit is marked Minimum Circuit Ampacity 36 amperes and Maximum Circuit Breaker 60 amperes. Available 75°C copper ampacities are 10 AWG = 35 amperes, 8 AWG = 50 amperes, and 6 AWG = 65 amperes. Which pairing uses the smallest conductor that satisfies the MCA and the largest breaker permitted by the nameplate?
Correct answer: A - 8 AWG copper with a 60-ampere breaker
For an ordinary continuous-duty AC motor with no special exception, which current basis generally controls branch-circuit conductor sizing, branch short-circuit and ground-fault protection, and motor overload protection?
Correct answer: C - Table full-load current for conductors and branch fault protection; nameplate current for overloads
The MD-ME exam also covers these domains. Drill them in the full free practice test:
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