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The CO-ME exam has 90 questions and runs 4 hours.
These 10 free CO-ME questions are organized by exam domain, so you can see how each part of the Colorado Master Electrician License Exam blueprint is tested. Reveal the answer and explanation under each question.
Before replacing a hybrid inverter, a qualified electrician opens and locks its AC supply disconnect. The display goes dark. The wiring diagram shows independent photovoltaic and battery feeds, each with an external DC disconnect. What remains necessary before the inverter's internal conductors can be treated as deenergized?
Correct answer: A - Isolate and lock out both DC feeds, control stored energy, and verify absence of voltage.
After a receptacle replacement on a 120/240 V multiwire branch circuit, two 120 V loads on opposite legs begin operating abnormally. Measurements at the loads show 76 V and 164 V from the respective ungrounded conductors to the shared neutral, while line-to-line voltage remains 240 V and each line-to-ground voltage remains 120 V. The two line-to-neutral readings shift in opposite directions when a load changes. The circuit is then deenergized. What failure does this voltage pattern indicate?
Correct answer: A - An open or high-resistance connection in the shared neutral
During commissioning of a feeder-supplied panel, a clamp meter detects several amperes on the feeder's copper equipment grounding conductor. The current rises and falls as ordinary 120 V resistive loads are switched. Feeder-neutral continuity is satisfactory, and insulation tests performed with the branch circuits deenergized and isolated reveal no phase-to-ground faults. Where should the electrician look first?
Correct answer: B - For an improper neutral-to-enclosure connection in the feeder-supplied panel
A service grounding electrode system consists of two properly installed 8 ft rods spaced 8 ft apart and bonded together. No other qualifying electrodes are present. A valid measurement of the two-rod system shows 38 ohms to earth. There is no project specification or local requirement for a lower resistance. Which statement correctly applies the NEC's supplemental-electrode requirement?
Correct answer: C - The two-rod arrangement satisfies the supplemental-electrode requirement without a 25-ohm acceptance limit for the pair.
A nonmetallic device box will receive two 12/2-with-ground cables and one 12/3-with-ground cable. All seven insulated conductors terminate or splice in the box. The box also contains one duplex receptacle on a single yoke, internal cable clamps, and two insulated 12 AWG pigtails that remain entirely inside the box. All equipment grounding conductors are 12 AWG. The volume allowance for 12 AWG is 2.25 cubic inches. Choose the smallest box with sufficient marked volume.
Correct answer: C - 25 cubic inches
Replacement process equipment is needed for a Class I, Division 1, Group C location. The documented minimum autoignition temperature of the vapor mixture is 190 degrees C. Electrical ratings and ambient-temperature suitability are otherwise satisfactory for all four candidates. Which nameplate is suitable for the classified location and its temperature limitation?
Correct answer: C - Class I, Division 1, Group C; T4, maximum surface temperature 135 degrees C
A listed rooftop air-conditioning unit is marked 'MCA 28 A; maximum fuse 45 A,' and its instructions permit fuses only. Starting performance has been checked for 40 A dual-element fuses. The conductor ampacities in the proposals already account for temperature and installation conditions. Which branch-circuit proposal meets the equipment requirements?
Correct answer: D - 35 A allowable conductor ampacity with 40 A dual-element fuses.
At an existing nongrounding receptacle, the cable contains only an ungrounded conductor and a neutral. Neither an equipment grounding conductor nor a qualifying metal grounding path is present. This is a receptacle replacement, not a circuit extension; other required circuit protection is already provided. Which replacement is permitted without adding an equipment grounding conductor?
Correct answer: D - A GFCI receptacle marked 'No Equipment Ground,' with its grounding terminal unconnected
A continuous-duty, 20 hp, 460 V, three-phase motor has a nameplate current of 24 A, a marked service factor of 1.20, and a marked temperature rise of 50 degrees C. The applicable NEC table full-load current is 27 A. For a separate overload device, what is the ordinary maximum trip-current value before considering any allowance for failure to start or carry the load?
Correct answer: A - 30.0 A
A new dwelling qualifies for the 2026 NEC optional service-load calculation. Its general-load subtotal before demand factors is 34,000 VA, excluding heating, cooling, and electric vehicle supply equipment. Heating consists of one thermostat-controlled, non-storage 10,000 VA resistance-heating unit; the alternative air-conditioning load is 6,000 VA. Heating and cooling cannot operate together. The EV supply equipment is rated 9,600 VA and has no load-management arrangement. What is the total calculated load, before conductor and overcurrent-device sizing?
Correct answer: B - 34,500 VA
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