Idaho Master Electrician Exam Newest
(2026 Update) Actual Practice Questions
– Set 100 Most Common Exam
Questions And Answers In Details 100%
Verified Exam
Q1.
A 240V single-phase load draws 30 amps continuously. What is the minimum
conductor ampacity required under NEC continuous load rules?
A. 30A
B. 35A
C. 37.5A
D. 40A
Correct Answer: D ✔ [40A]
Rationale: Continuous loads require sizing at 125% of load. 30A × 1.25 = 37.5A,
so next standard size is 40A.
Q2.
Which NEC article governs grounding and bonding?
A. Article 210
B. Article 250
C. Article 300
D. Article 310
,Correct Answer: B ✔ [Article 250]
Rationale: Article 250 specifically covers grounding and bonding requirements.
Q3.
A 3-phase motor operates at 480V drawing 18A. What is the minimum branch
circuit conductor ampacity?
A. 18A
B. 20A
C. 22.5A
D. 25A
Correct Answer: C ✔ [22.5A]
Rationale: Motor conductors are sized at 125% of full-load current. 18A × 1.25 =
22.5A.
Q4.
What is the maximum number of 12 AWG THHN conductors allowed in a 3/4"
EMT conduit?
A. 7
B. 9
C. 10
D. 12
Correct Answer: B ✔ [9]
Rationale: Conduit fill tables limit 12 AWG THHN in 3/4" EMT to 9 conductors at
40% fill.
Q5.
What is the purpose of a GFCI device?
,A. Prevent overload
B. Prevent short circuit
C. Protect against ground-fault shock
D. Increase voltage stability
Correct Answer: C ✔ [Protect against ground-fault shock]
Rationale: GFCIs detect leakage current and disconnect power to prevent
electric shock.
Q6.
A 120V circuit supplies 1800W. What is the load current?
A. 12A
B. 15A
C. 18A
D. 20A
Correct Answer: B ✔ [15A]
Rationale: I = P ÷ V → 1800 ÷ 120 = 15A.
Q7.
Which device protects against overcurrent?
A. Switch
B. Receptacle
C. Circuit breaker
D. Transformer
Correct Answer: C ✔ [Circuit breaker]
Rationale: Circuit breakers interrupt current during overload or short circuit
conditions.
, Q8.
What is the minimum clearance for overhead service conductors above residential
property?
A. 8 ft
B. 10 ft
C. 12 ft
D. 15 ft
Correct Answer: C ✔ [12 ft]
Rationale: NEC requires at least 12 feet clearance over residential driveways and
areas.
Q9.
A 480V 3-phase load draws 25A. What is approximate power in kW (power factor
1)?
A. 10.4 kW
B. 15.6 kW
C. 20.8 kW
D. 25.0 kW
Correct Answer: C ✔ [20.8 kW]
Rationale: kW = √3 × V × I ÷ 1000 = 1.732 × 480 × 25 ÷ 1000 ≈ 20.8 kW.
Q10.
Which conductor is used for grounding?
A. Hot conductor
B. Neutral conductor
C. Equipment grounding conductor
D. Ungrounded conductor
(2026 Update) Actual Practice Questions
– Set 100 Most Common Exam
Questions And Answers In Details 100%
Verified Exam
Q1.
A 240V single-phase load draws 30 amps continuously. What is the minimum
conductor ampacity required under NEC continuous load rules?
A. 30A
B. 35A
C. 37.5A
D. 40A
Correct Answer: D ✔ [40A]
Rationale: Continuous loads require sizing at 125% of load. 30A × 1.25 = 37.5A,
so next standard size is 40A.
Q2.
Which NEC article governs grounding and bonding?
A. Article 210
B. Article 250
C. Article 300
D. Article 310
,Correct Answer: B ✔ [Article 250]
Rationale: Article 250 specifically covers grounding and bonding requirements.
Q3.
A 3-phase motor operates at 480V drawing 18A. What is the minimum branch
circuit conductor ampacity?
A. 18A
B. 20A
C. 22.5A
D. 25A
Correct Answer: C ✔ [22.5A]
Rationale: Motor conductors are sized at 125% of full-load current. 18A × 1.25 =
22.5A.
Q4.
What is the maximum number of 12 AWG THHN conductors allowed in a 3/4"
EMT conduit?
A. 7
B. 9
C. 10
D. 12
Correct Answer: B ✔ [9]
Rationale: Conduit fill tables limit 12 AWG THHN in 3/4" EMT to 9 conductors at
40% fill.
Q5.
What is the purpose of a GFCI device?
,A. Prevent overload
B. Prevent short circuit
C. Protect against ground-fault shock
D. Increase voltage stability
Correct Answer: C ✔ [Protect against ground-fault shock]
Rationale: GFCIs detect leakage current and disconnect power to prevent
electric shock.
Q6.
A 120V circuit supplies 1800W. What is the load current?
A. 12A
B. 15A
C. 18A
D. 20A
Correct Answer: B ✔ [15A]
Rationale: I = P ÷ V → 1800 ÷ 120 = 15A.
Q7.
Which device protects against overcurrent?
A. Switch
B. Receptacle
C. Circuit breaker
D. Transformer
Correct Answer: C ✔ [Circuit breaker]
Rationale: Circuit breakers interrupt current during overload or short circuit
conditions.
, Q8.
What is the minimum clearance for overhead service conductors above residential
property?
A. 8 ft
B. 10 ft
C. 12 ft
D. 15 ft
Correct Answer: C ✔ [12 ft]
Rationale: NEC requires at least 12 feet clearance over residential driveways and
areas.
Q9.
A 480V 3-phase load draws 25A. What is approximate power in kW (power factor
1)?
A. 10.4 kW
B. 15.6 kW
C. 20.8 kW
D. 25.0 kW
Correct Answer: C ✔ [20.8 kW]
Rationale: kW = √3 × V × I ÷ 1000 = 1.732 × 480 × 25 ÷ 1000 ≈ 20.8 kW.
Q10.
Which conductor is used for grounding?
A. Hot conductor
B. Neutral conductor
C. Equipment grounding conductor
D. Ungrounded conductor
