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1. A 240V single-phase load draws 18A. What is the minimum ampacity
required for the circuit conductors for continuous operation at 125%?
A. 18A
B. 22.5A
C. 30A
D. 45A
✔ Correct Answer: (C. 30A)
*Rationale: 18A × 1.25 = 22.5A minimum, next standard size is 30A conductor
rating required.
2. According to NEC, the maximum voltage drop recommended for branch
circuits is:
A. 2%
B. 3%
C. 5%
D. 10%
,✔ Correct Answer: (B. 3%)
*Rationale: NEC recommends 3% maximum voltage drop on branch circuits for
efficiency and performance.
3. A motor is rated at 10 HP, 230V, single-phase. What is the minimum circuit
ampacity approximately?
A. 30A
B. 40A
C. 50A
D. 60A
✔ Correct Answer: (C. 50A)
*Rationale: NEC tables estimate ~43–50A for 10 HP single-phase motor circuits
depending on code table rounding.
4. Which device protects against overcurrent and short circuit?
A. Transformer
B. Conduit
C. Circuit breaker
D. Switch
✔ Correct Answer: (C. Circuit breaker)
*Rationale: Circuit breakers automatically interrupt current during overload or
short circuit conditions.
5. The purpose of grounding in an electrical system is primarily to:
A. Increase voltage
B. Provide a return path for normal current
C. Stabilize voltage and provide fault path
D. Reduce conductor size
,✔ Correct Answer: (C. Stabilize voltage and provide fault path)
*Rationale: Grounding ensures safety by providing a low-resistance fault current
path and voltage stabilization.
6. What is the minimum working clearance in front of electrical equipment
rated 1200A at 480V?
A. 3 feet
B. 4 feet
C. 5 feet
D. 6 feet
✔ Correct Answer: (C. 5 feet)
*Rationale: NEC requires increased working space for high voltage/high current
equipment (up to 5 feet depth).
7. A 20A, 120V circuit supplies lighting. Maximum load allowed for continuous
operation is:
A. 12A
B. 15A
C. 16A
D. 20A
✔ Correct Answer: (B. 15A)
*Rationale: Continuous loads are limited to 80% of breaker rating: 20A × 0.8 =
16A, closest safe value is 15A.
8. Which of the following is considered a continuous load?
A. Refrigerator
B. Lighting operating over 3 hours
C. Dishwasher
D. Garage door motor
, ✔ Correct Answer: (B. Lighting operating over 3 hours)
*Rationale: Continuous load is one expected to run for 3 hours or more.
9. The purpose of a GFCI device is to protect against:
A. Overvoltage
B. Ground faults
C. Lightning strikes
D. Overheating conductors
✔ Correct Answer: (B. Ground faults)
*Rationale: GFCIs detect imbalance between hot and neutral indicating leakage
current.
10.What is the minimum size copper grounding electrode conductor for a 200A
service?
A. #6 AWG
B. #4 AWG
C. #2 AWG
D. #1 AWG
✔ Correct Answer: (B. #4 AWG)
*Rationale: NEC Table 250.66 typically requires #4 copper for 200A service.
11.A 3-phase load draws 25A at 480V. What is approximate power (kW)?
A. 10 kW
B. 15 kW
C. 20 kW
D. 25 kW