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1. What is the minimum cover depth for direct-buried residential branch
circuits rated 120V or less with GFCI protection?
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
✔ Correct Answer: B (12 inches)
Explanation: NEC permits 12 inches for GFCI-protected residential branch
circuits ≤120V.
2. A continuous load is defined as a load where the maximum current is
expected to continue for how long?
A. 30 minutes or more
B. 1 hour or more
C. 2 hours or more
D. 3 hours or more
✔ Correct Answer: D (3 hours or more)
Explanation: NEC defines continuous load as 3 hours or longer.
3. What is the maximum number of 12 AWG conductors allowed in a 4-inch
square box with a volume of 21 cubic inches?
A. 7
B. 8
C. 9
, D. 10
✔ Correct Answer: B (8)
Explanation: Each 12 AWG requires 2.25 cubic inches; 21 ÷ 2.25 ≈ 9 but
allowances reduce usable count to 8.
4. Which conductor is required to be bonded to all metal enclosures and
equipment?
A. Neutral conductor
B. Grounded conductor
C. Equipment grounding conductor
D. Ungrounded conductor
✔ Correct Answer: C (Equipment grounding conductor)
Explanation: The EGC ensures fault current path and bonding.
5. What is the standard voltage for a single-phase residential service in the
U.S.?
A. 120V
B. 208V
C. 240V
D. 277V
✔ Correct Answer: C (240V)
Explanation: Residential services are typically 120/240V single-phase.
6. What type of motor duty requires the highest overload protection setting?
A. Continuous duty
B. Intermittent duty
C. Short-time duty
D. Variable duty
✔ Correct Answer: A (Continuous duty)
Explanation: Continuous motors require full protection due to sustained
operation.
7. Which NEC article covers grounding and bonding?
A. Article 110
, B. Article 250
C. Article 300
D. Article 400
✔ Correct Answer: B (Article 250)
Explanation: Article 250 governs grounding and bonding rules.
8. What is the maximum overcurrent protection for a 14 AWG copper
conductor?
A. 10A
B. 15A
C. 20A
D. 25A
✔ Correct Answer: B (15A)
Explanation: NEC limits 14 AWG copper to 15 amps.
9. A transformer has a primary voltage of 480V and secondary of 120V. What
is the turns ratio?
A. 2:1
B. 3:1
C. 4:1
D. 5:1
✔ Correct Answer: C (4:1)
Explanation: 480 ÷ 120 = 4:1 ratio.
10.What is required for all 125V, single-phase, 15- and 20-amp receptacles in
dwelling bathrooms?
A. AFCI protection
B. GFCI protection
C. Surge protection
D. Isolation transformer
✔ Correct Answer: B (GFCI protection)
Explanation: NEC mandates GFCI protection in bathrooms.