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.
These 10 free C-206 questions are organized by exam domain, so you can see how each part of the Electrical System Installation 1 blueprint is tested. Reveal the answer and explanation under each question.
Domain 1: adhering to motor control installation safety rules
Question 1
Following the employer's live-dead-live procedure, a technician proves a contact voltage tester on a live source, then obtains zero at every required test point on an isolated 480-V starter. The tester fails its immediate final check on a source independently confirmed live. When the tester failed is unknown. What is the status of the starter's absence-of-voltage verification?
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Correct answer: D - Unverified; repeat the complete verification using a reliable, appropriately rated tester.
Domain 2: using proper PPE
Question 2
An authorized diagnostic task in a 600Y/347-V cabinet exposes a qualified worker to more than one phase. Assessed incident energy is 6.6 cal/cm² at the working distance. Other required controls and PPE are in place, including protectors for the rubber insulating gloves. Select the pairing that meets both the voltage-insulation and clothing arc-rating requirements.
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Correct answer: B - Class 0 gloves rated 1,000 V AC; clothing arc-rated 8 cal/cm².
A 24-V DC starter should have NC STOP and overload contacts in series with K1's coil, and K1's NO holding contact across the momentary NO START contact. During commissioning, K1 energizes while START is held. Pressing STOP while holding START does not release K1; releasing START does. After isolation, STOP opens correctly when pressed and the overload contact tests closed. Which single wiring error accounts for both symptoms?
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Correct answer: C - The holding contact is connected across STOP instead of START.
Domain 4: sizing circuit protection
Question 4
At a starter-setting review, a motor's nameplate shows 11 A, its code-table full-load current is 14 A, and its measured current at the present load is 9 A. The correctly selected overload relay is set to 11 A. Its instructions require setting the dial to motor nameplate current; the dial does not indicate actual trip current. Operation has been normal. What should the reviewer recommend?
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Correct answer: A - Retain 11 A; it is the setting required by this relay's calibration.
Question 5
A project using the 2023 NEC requires dual-element time-delay fuses, other than Class CC, for a 15-hp, 460-V, three-phase squirrel-cage motor. The motor is single-speed, with normal speed and torque characteristics. Nameplate current is 19.2 A; Table 430.250 gives 21 A. The project specification caps each fuse at 175% of the applicable full-load current and does not permit a rating above that calculated ceiling. What is the largest offered fuse rating that satisfies this specification?
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Correct answer: B - 35 A
Domain 6: installing and testing ground systems
Question 6
The installation procedure requires a motor-frame protective bond to have lead-corrected resistance no greater than 0.10 Ω. On safely isolated equipment, the specified test method gives 0.15 Ω with the leads shorted together and 0.22 Ω from the frame to the protective-earth bar. Lead compensation is not active, and the other required bond checks are satisfactory. Which entry belongs in the test record?
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Correct answer: C - 0.07 Ω; pass, because the lead-corrected bond resistance is below the limit.
Domain 7: wiring motors for high and low voltage
Question 7
A conventional nine-lead, 230/460-V WYE motor with standard T1-T9 numbering is being connected for 460 V. With the motor isolated and absence of voltage verified, inspection finds L1-T1, L2-T2 and L3-T3. The pairs T4-T7, T5-T8 and T6-T9 occupy three terminal positions, but a copper comb joins those positions electrically. How should the installer correct the motor connections?
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Correct answer: D - Remove the comb and keep the three specified lead pairs electrically separate.
Domain 8: selecting and preparing wire for installation
Question 8
A retrofit will place existing, undamaged copper conductors in a raceway classified as a wet location. They are marked 600 V, THHN/THWN-2. Circuit voltage is 480 V, conductor operating temperature will be 70°C, and no oil is present. Ampacity and terminal-temperature checks are satisfactory. An inspector questions the THHN marking. Which response is technically sound?
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Correct answer: C - Retain the conductors because their THWN-2 rating covers these wet-location conditions.
Domain 9: attaching of wire to terminal strips and components/motors
Question 9
A pressure switch's C-NC contact must open at 600 kPa on rising pressure and reclose at 500 kPa on falling pressure. In a controlled test with the electrical circuit isolated, it opens correctly. Pressure is then reduced from 650 kPa to 550 kPa, where the contact remains open. The finding supports which assessment?
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Correct answer: B - The contact is behaving correctly because pressure has not reached its reset point.
Domain 10: routing of wire with raceways/conduits
Question 10
A cabinet door must open fully for the specified service access. With the cabinet isolated, its harness becomes taut before the door reaches that position. The terminations and fixed supports are sound, and adequate spare conductor length remains inside the cabinet wire duct. Which rework preserves the required access while relieving the harness strain?
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Correct answer: A - Route the available slack into a supported loop clear of the hinge.