MARYLAND MASTER ELECTRICIAN EXAM 150
QUESTIONS WITH ANSWERS & DETAILED
RATIONALES | 2026/2027 EDITION
Core Domains
• Electrical Theory: Ohm's Law, AC/DC Theory, Power Calculations,
Transformers, Motors
• Wiring and Protection: NEC Articles 100, 110, 200-210, 215-225, 230, 240,
250-285
• Wiring Methods and Materials: NEC Articles 300, 310-314, 320-330, 332-
356, 358-374
• Equipment for General Use: NEC Articles 400-411, 422-427, 430-450, 455-
490
• Special Occupancies: NEC Articles 500-525, 530-547, 550-590
• Special Equipment: NEC Articles 600-675, 680-695
• Calculations: Load Calculations, Feeder Sizing, Motor Calculations,
Voltage Drop
• Maryland Licensing & Regulations: Board Requirements, Insurance,
Permitting
This comprehensive examination guide is designed for candidates preparing for
the Maryland Master Electrician Exam for the 2026/2027 testing cycle. The exam
is administered by PSI and overseen by the Maryland Board of Master
Electricians. It consists of 90 questions (100 points) with a 4-hour time limit and a
minimum passing score of 70% . The exam is open-book and based on the 2020
National Electrical Code (NEC) [citation:3,11]. Topics include electrical theory,
wiring and protection, wiring methods and materials, equipment for general use,
special occupancies, special equipment, special communications, and calculations
[citation:1,11]. This resource features 150 practice questions with verified
answers and detailed rationales to ensure exam readiness.
,SECTION 1: ELECTRICAL THEORY (Questions 1-20)
Question 1
What is the formula for Ohm's Law?
A. V = I × R
B. V = I / R
C. I = V × R
D. R = V × I
Correct answer: A
RATIONALE: Ohm's Law states that voltage (V) equals current (I) multiplied
by resistance (R): V = I × R . This fundamental law is essential for all electrical
calculations and is heavily tested on the exam .
Question 2
In a purely inductive AC circuit, how does current relate to voltage?
A. Current leads voltage by 90°
B. Current lags voltage by 90°
C. Current is in phase with voltage
D. Current is 180° out of phase with voltage
Correct answer: B
RATIONALE: In a purely inductive circuit, current lags voltage by 90°. This
is represented by the mnemonic "ELI" (E leads I). This phase relationship is
fundamental to understanding AC circuits and is tested on the electrical theory
portion of the exam .
Question 3
What is the formula for electrical power in watts?
,A. P = I² × R
B. P = V × I
C. P = V / I
D. Both A and B
Correct answer: D
RATIONALE: Electrical power can be expressed as P = V × I or P = I² × R.
Power is measured in watts and represents the rate at which electrical energy is
converted. These formulas are essential for load calculations on the exam .
Question 4
In a balanced three-phase wye system, what is the relationship between line
voltage and phase voltage?
A. V_L = V_phase
B. V_L = √3 × V_phase
C. V_L = V_phase / √3
D. V_L = 2 × V_phase
Correct answer: B
RATIONALE: In a balanced 3-phase wye system, line voltage is equal to the
phase voltage multiplied by √3 [citation:2,4]. This is a fundamental relationship
used in power distribution calculations.
Question 5
What is the formula for three-phase power?
A. P = V × I
B. P = √3 × V_L × I_L × PF
C. P = I² × R
D. P = V² / R
Correct answer: B
, RATIONALE: Three-phase power is calculated using P = √3 × V_L × I_L ×
PF. This formula accounts for the three phases and power factor. Calculations
make up 30 points of the exam and are heavily weighted .
Question 6
What is the standard frequency of AC power in the United States?
A. 50 Hz
B. 60 Hz
C. 120 Hz
D. 400 Hz
Correct answer: B
RATIONALE: The standard frequency for AC power in the United States is 60
Hz. The exam is based on the 2020 NEC which assumes this standard.
Question 7
In a purely capacitive AC circuit, how does current relate to voltage?
A. Current leads voltage by 90°
B. Current lags voltage by 90°
C. Current is in phase with voltage
D. Current is 180° out of phase with voltage
Correct answer: A
RATIONALE: In a purely capacitive circuit, current leads voltage by 90°
(represented by "ICE" - I leads E). Understanding phase relationships is important
for power factor calculations.
Question 8
What is the relationship between frequency and inductive reactance?
A. XL increases as frequency increases
B. XL decreases as frequency increases
QUESTIONS WITH ANSWERS & DETAILED
RATIONALES | 2026/2027 EDITION
Core Domains
• Electrical Theory: Ohm's Law, AC/DC Theory, Power Calculations,
Transformers, Motors
• Wiring and Protection: NEC Articles 100, 110, 200-210, 215-225, 230, 240,
250-285
• Wiring Methods and Materials: NEC Articles 300, 310-314, 320-330, 332-
356, 358-374
• Equipment for General Use: NEC Articles 400-411, 422-427, 430-450, 455-
490
• Special Occupancies: NEC Articles 500-525, 530-547, 550-590
• Special Equipment: NEC Articles 600-675, 680-695
• Calculations: Load Calculations, Feeder Sizing, Motor Calculations,
Voltage Drop
• Maryland Licensing & Regulations: Board Requirements, Insurance,
Permitting
This comprehensive examination guide is designed for candidates preparing for
the Maryland Master Electrician Exam for the 2026/2027 testing cycle. The exam
is administered by PSI and overseen by the Maryland Board of Master
Electricians. It consists of 90 questions (100 points) with a 4-hour time limit and a
minimum passing score of 70% . The exam is open-book and based on the 2020
National Electrical Code (NEC) [citation:3,11]. Topics include electrical theory,
wiring and protection, wiring methods and materials, equipment for general use,
special occupancies, special equipment, special communications, and calculations
[citation:1,11]. This resource features 150 practice questions with verified
answers and detailed rationales to ensure exam readiness.
,SECTION 1: ELECTRICAL THEORY (Questions 1-20)
Question 1
What is the formula for Ohm's Law?
A. V = I × R
B. V = I / R
C. I = V × R
D. R = V × I
Correct answer: A
RATIONALE: Ohm's Law states that voltage (V) equals current (I) multiplied
by resistance (R): V = I × R . This fundamental law is essential for all electrical
calculations and is heavily tested on the exam .
Question 2
In a purely inductive AC circuit, how does current relate to voltage?
A. Current leads voltage by 90°
B. Current lags voltage by 90°
C. Current is in phase with voltage
D. Current is 180° out of phase with voltage
Correct answer: B
RATIONALE: In a purely inductive circuit, current lags voltage by 90°. This
is represented by the mnemonic "ELI" (E leads I). This phase relationship is
fundamental to understanding AC circuits and is tested on the electrical theory
portion of the exam .
Question 3
What is the formula for electrical power in watts?
,A. P = I² × R
B. P = V × I
C. P = V / I
D. Both A and B
Correct answer: D
RATIONALE: Electrical power can be expressed as P = V × I or P = I² × R.
Power is measured in watts and represents the rate at which electrical energy is
converted. These formulas are essential for load calculations on the exam .
Question 4
In a balanced three-phase wye system, what is the relationship between line
voltage and phase voltage?
A. V_L = V_phase
B. V_L = √3 × V_phase
C. V_L = V_phase / √3
D. V_L = 2 × V_phase
Correct answer: B
RATIONALE: In a balanced 3-phase wye system, line voltage is equal to the
phase voltage multiplied by √3 [citation:2,4]. This is a fundamental relationship
used in power distribution calculations.
Question 5
What is the formula for three-phase power?
A. P = V × I
B. P = √3 × V_L × I_L × PF
C. P = I² × R
D. P = V² / R
Correct answer: B
, RATIONALE: Three-phase power is calculated using P = √3 × V_L × I_L ×
PF. This formula accounts for the three phases and power factor. Calculations
make up 30 points of the exam and are heavily weighted .
Question 6
What is the standard frequency of AC power in the United States?
A. 50 Hz
B. 60 Hz
C. 120 Hz
D. 400 Hz
Correct answer: B
RATIONALE: The standard frequency for AC power in the United States is 60
Hz. The exam is based on the 2020 NEC which assumes this standard.
Question 7
In a purely capacitive AC circuit, how does current relate to voltage?
A. Current leads voltage by 90°
B. Current lags voltage by 90°
C. Current is in phase with voltage
D. Current is 180° out of phase with voltage
Correct answer: A
RATIONALE: In a purely capacitive circuit, current leads voltage by 90°
(represented by "ICE" - I leads E). Understanding phase relationships is important
for power factor calculations.
Question 8
What is the relationship between frequency and inductive reactance?
A. XL increases as frequency increases
B. XL decreases as frequency increases
