Idaho Master Electrician Exam
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
QUESTION 1
Which NEC article primarily governs electrical grounding and bonding
requirements?
A. Article 250
B. Article 300
C. Article 310
D. Article 220
Correct Answer: A
Rationale: Article 250 of the NEC specifically covers grounding and bonding
systems, including grounding electrode systems, equipment grounding
conductors, bonding of electrical systems, and grounding methods. Articles 300,
310, and 220 deal with wiring methods, conductor ampacity, and load
calculations respectively, not grounding.
QUESTION 2
What is the minimum burial depth for a 120V residential branch circuit in PVC
conduit under a 2-inch concrete slab?
A. 12 inches
B. 18 inches
,C. 6 inches
D. 24 inches
Correct Answer: B
Rationale: NEC Table 300.5 requires PVC conduit under residential concrete slabs
to be buried at least 18 inches unless specific exceptions apply. Shallower depths
are not permitted for standard installations due to physical protection
requirements.
QUESTION 3
Which conductor is primarily used as the equipment grounding conductor?
A. Neutral conductor
B. Hot conductor
C. Bare or green insulated conductor
D. Ungrounded conductor
Correct Answer: C
Rationale: Equipment grounding conductors are identified as bare copper or
green insulated conductors. They provide a low-resistance path for fault current
to ensure overcurrent protection devices operate properly.
QUESTION 4
What is the purpose of a GFCI device?
A. Protect against overloads
B. Protect against short circuits
C. Protect against ground-fault shock hazards
D. Increase circuit voltage stability
Correct Answer: D
,Rationale: GFCI devices are designed to protect personnel from electrical shock
by detecting imbalance between hot and neutral conductors, not to regulate
voltage stability.
QUESTION 5
The correct formula for single-phase power is:
A. P = V × I × PF
B. P = I² × R
C. P = V ÷ I
D. P = V × R
Correct Answer: A
Rationale: Real power in single-phase systems is calculated as voltage multiplied
by current multiplied by power factor. The other formulas represent Ohm’s law
or resistive relationships, not true power.
QUESTION 6
What is the maximum voltage drop recommended by NEC for branch circuits?
A. 10%
B. 5%
C. 3%
D. 8%
Correct Answer: B
Rationale: NEC recommends a maximum of 5% total voltage drop, with 3% for
branch circuits and 2% for feeders, to maintain equipment efficiency and
performance.
QUESTION 7
, Which device protects against overloads and short circuits?
A. Transformer
B. Circuit breaker
C. Capacitor
D. Conduit
Correct Answer: C
Rationale: Circuit breakers are overcurrent protection devices that automatically
disconnect power during overloads or short circuits.
QUESTION 8
The neutral conductor is typically grounded at:
A. Load side only
B. Multiple points in system
C. Service disconnect
D. Branch circuit outlet
Correct Answer: D
Rationale: The neutral is grounded at the service disconnect point only to avoid
parallel current paths and ensure system stability.
QUESTION 9
Which NEC article covers conductors and their insulation types?
A. Article 310
B. Article 250
C. Article 400
D. Article 725
Correct Answer: A
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
QUESTION 1
Which NEC article primarily governs electrical grounding and bonding
requirements?
A. Article 250
B. Article 300
C. Article 310
D. Article 220
Correct Answer: A
Rationale: Article 250 of the NEC specifically covers grounding and bonding
systems, including grounding electrode systems, equipment grounding
conductors, bonding of electrical systems, and grounding methods. Articles 300,
310, and 220 deal with wiring methods, conductor ampacity, and load
calculations respectively, not grounding.
QUESTION 2
What is the minimum burial depth for a 120V residential branch circuit in PVC
conduit under a 2-inch concrete slab?
A. 12 inches
B. 18 inches
,C. 6 inches
D. 24 inches
Correct Answer: B
Rationale: NEC Table 300.5 requires PVC conduit under residential concrete slabs
to be buried at least 18 inches unless specific exceptions apply. Shallower depths
are not permitted for standard installations due to physical protection
requirements.
QUESTION 3
Which conductor is primarily used as the equipment grounding conductor?
A. Neutral conductor
B. Hot conductor
C. Bare or green insulated conductor
D. Ungrounded conductor
Correct Answer: C
Rationale: Equipment grounding conductors are identified as bare copper or
green insulated conductors. They provide a low-resistance path for fault current
to ensure overcurrent protection devices operate properly.
QUESTION 4
What is the purpose of a GFCI device?
A. Protect against overloads
B. Protect against short circuits
C. Protect against ground-fault shock hazards
D. Increase circuit voltage stability
Correct Answer: D
,Rationale: GFCI devices are designed to protect personnel from electrical shock
by detecting imbalance between hot and neutral conductors, not to regulate
voltage stability.
QUESTION 5
The correct formula for single-phase power is:
A. P = V × I × PF
B. P = I² × R
C. P = V ÷ I
D. P = V × R
Correct Answer: A
Rationale: Real power in single-phase systems is calculated as voltage multiplied
by current multiplied by power factor. The other formulas represent Ohm’s law
or resistive relationships, not true power.
QUESTION 6
What is the maximum voltage drop recommended by NEC for branch circuits?
A. 10%
B. 5%
C. 3%
D. 8%
Correct Answer: B
Rationale: NEC recommends a maximum of 5% total voltage drop, with 3% for
branch circuits and 2% for feeders, to maintain equipment efficiency and
performance.
QUESTION 7
, Which device protects against overloads and short circuits?
A. Transformer
B. Circuit breaker
C. Capacitor
D. Conduit
Correct Answer: C
Rationale: Circuit breakers are overcurrent protection devices that automatically
disconnect power during overloads or short circuits.
QUESTION 8
The neutral conductor is typically grounded at:
A. Load side only
B. Multiple points in system
C. Service disconnect
D. Branch circuit outlet
Correct Answer: D
Rationale: The neutral is grounded at the service disconnect point only to avoid
parallel current paths and ensure system stability.
QUESTION 9
Which NEC article covers conductors and their insulation types?
A. Article 310
B. Article 250
C. Article 400
D. Article 725
Correct Answer: A
