,NYC DCAS Electrician Exam Questions and Verified Answers
with Detailed Rationales | 2026/2027 Edition
This comprehensive study guide contains practice questions with verified answers and detailed
rationales for the NYC DCAS Electrician Civil Service Examination (Exam No. 6048/6049). The content
reflects the 2026/2027 examination cycle and covers electrical theory, NEC compliance, NYC Electrical
Code amendments, wiring methods, motors, transformers, grounding, load calculations, safety, and
blueprint reading.
SECTION 1: ELECTRICAL THEORY & CALCULATIONS
1. What is the SI unit of electrical current?
A) Volt
B) Ohm
C) Ampere
D) Watt
Correct Answer: C
Rationale: The ampere (A) is the SI base unit for electric current, representing the flow of one coulomb
of charge per second. Voltage is measured in volts, resistance in ohms, and power in watts.
2. The resistance of a conductor is directly proportional to its:
A) Cross-sectional area
B) Length
C) Temperature coefficient
D) Conductivity
Correct Answer: B
Rationale: Resistance is directly proportional to the length of a conductor (R ∝ L). It is inversely
proportional to cross-sectional area (R ∝ 1/A). Longer conductors have more resistance; larger cross-
sectional area reduces resistance.
3. What is the total resistance of three 12Ω resistors connected in parallel?
A) 4Ω
B) 12Ω
C) 36Ω
D) 3Ω
Correct Answer: A
Rationale: For parallel resistors, 1/Rt = 1/R₁ + 1/R₂ + 1/R₃ = 1/12 + 1/12 + 1/12 = 3/12 = 1/4; therefore Rt
= 4Ω. Parallel resistance is always less than the smallest individual resistor.
,4. According to Ohm's Law, if voltage increases while resistance remains constant, current will:
A) Decrease
B) Remain the same
C) Increase
D) Fluctuate
Correct Answer: C
Rationale: Ohm's Law states I = V / R. With R constant, current is directly proportional to voltage;
increasing voltage increases current proportionally.
5. What is the power dissipated by a 10Ω resistor with 2 amperes of current flowing through it?
A) 20W
B) 40W
C) 5W
D) 100W
Correct Answer: B
Rationale: Power = I² × R = (2A)² × 10Ω = 4 × 10 = 40W. Alternatively, P = V × I, where V = I × R = 20V, so
P = 20V × 2A = 40W.
6. In a series circuit, the total resistance is:
A) The same across each component
B) Equal to the reciprocal of the sum of reciprocals
C) The sum of individual resistances
D) Divided equally among components
Correct Answer: C
Rationale: In a series circuit, current has only one path, so resistances add directly: R_total = R₁ + R₂ +
R₃...
7. In a parallel circuit, voltage is:
A) Different across each branch
B) The same across all branches
C) The sum of branch voltages
D) Divided by the number of branches
Correct Answer: B
Rationale: Voltage is constant across all branches in a parallel circuit; each branch receives the full
source voltage.
, 8. A 120-volt circuit has a resistance of 20 ohms. Approximately how much current flows?
A) 2 A
B) 4 A
C) 6 A
D) 10 A
Correct Answer: C
Rationale: Using I = V / R: 120 ÷ 20 = 6 amperes.
9. What is the unit of electrical power?
A) Volt
B) Ampere
C) Ohm
D) Watt
Correct Answer: D
Rationale: The watt (W) is the SI unit of electrical power, representing the rate of energy transfer.
Voltage is measured in volts, current in amperes, and resistance in ohms.
10. What is the correct formula for calculating electrical power (P) in a DC circuit?
A) P = I × R
B) P = V × I
C) P = V² / R
D) Both B and C
Correct Answer: D
Rationale: Power in DC circuits can be calculated using P = V × I (voltage times current) or, by
substituting Ohm's Law, P = V² / R or P = I² × R. Option A (P = I × R) calculates voltage, not power.
11. What does "power factor" describe in an AC system?
A) The ratio of true power to apparent power
B) The ratio of voltage to current
C) The relationship of volts and ohms
D) The product of voltage and current
Correct Answer: A
Rationale: Power factor = True Power (watts) / Apparent Power (volt-amperes). Low PF indicates
reactive loads like motors and transformers.
12. A 240V single-phase circuit supplies a 4800W electric water heater. What is the current draw?
A) 15A
B) 20A
with Detailed Rationales | 2026/2027 Edition
This comprehensive study guide contains practice questions with verified answers and detailed
rationales for the NYC DCAS Electrician Civil Service Examination (Exam No. 6048/6049). The content
reflects the 2026/2027 examination cycle and covers electrical theory, NEC compliance, NYC Electrical
Code amendments, wiring methods, motors, transformers, grounding, load calculations, safety, and
blueprint reading.
SECTION 1: ELECTRICAL THEORY & CALCULATIONS
1. What is the SI unit of electrical current?
A) Volt
B) Ohm
C) Ampere
D) Watt
Correct Answer: C
Rationale: The ampere (A) is the SI base unit for electric current, representing the flow of one coulomb
of charge per second. Voltage is measured in volts, resistance in ohms, and power in watts.
2. The resistance of a conductor is directly proportional to its:
A) Cross-sectional area
B) Length
C) Temperature coefficient
D) Conductivity
Correct Answer: B
Rationale: Resistance is directly proportional to the length of a conductor (R ∝ L). It is inversely
proportional to cross-sectional area (R ∝ 1/A). Longer conductors have more resistance; larger cross-
sectional area reduces resistance.
3. What is the total resistance of three 12Ω resistors connected in parallel?
A) 4Ω
B) 12Ω
C) 36Ω
D) 3Ω
Correct Answer: A
Rationale: For parallel resistors, 1/Rt = 1/R₁ + 1/R₂ + 1/R₃ = 1/12 + 1/12 + 1/12 = 3/12 = 1/4; therefore Rt
= 4Ω. Parallel resistance is always less than the smallest individual resistor.
,4. According to Ohm's Law, if voltage increases while resistance remains constant, current will:
A) Decrease
B) Remain the same
C) Increase
D) Fluctuate
Correct Answer: C
Rationale: Ohm's Law states I = V / R. With R constant, current is directly proportional to voltage;
increasing voltage increases current proportionally.
5. What is the power dissipated by a 10Ω resistor with 2 amperes of current flowing through it?
A) 20W
B) 40W
C) 5W
D) 100W
Correct Answer: B
Rationale: Power = I² × R = (2A)² × 10Ω = 4 × 10 = 40W. Alternatively, P = V × I, where V = I × R = 20V, so
P = 20V × 2A = 40W.
6. In a series circuit, the total resistance is:
A) The same across each component
B) Equal to the reciprocal of the sum of reciprocals
C) The sum of individual resistances
D) Divided equally among components
Correct Answer: C
Rationale: In a series circuit, current has only one path, so resistances add directly: R_total = R₁ + R₂ +
R₃...
7. In a parallel circuit, voltage is:
A) Different across each branch
B) The same across all branches
C) The sum of branch voltages
D) Divided by the number of branches
Correct Answer: B
Rationale: Voltage is constant across all branches in a parallel circuit; each branch receives the full
source voltage.
, 8. A 120-volt circuit has a resistance of 20 ohms. Approximately how much current flows?
A) 2 A
B) 4 A
C) 6 A
D) 10 A
Correct Answer: C
Rationale: Using I = V / R: 120 ÷ 20 = 6 amperes.
9. What is the unit of electrical power?
A) Volt
B) Ampere
C) Ohm
D) Watt
Correct Answer: D
Rationale: The watt (W) is the SI unit of electrical power, representing the rate of energy transfer.
Voltage is measured in volts, current in amperes, and resistance in ohms.
10. What is the correct formula for calculating electrical power (P) in a DC circuit?
A) P = I × R
B) P = V × I
C) P = V² / R
D) Both B and C
Correct Answer: D
Rationale: Power in DC circuits can be calculated using P = V × I (voltage times current) or, by
substituting Ohm's Law, P = V² / R or P = I² × R. Option A (P = I × R) calculates voltage, not power.
11. What does "power factor" describe in an AC system?
A) The ratio of true power to apparent power
B) The ratio of voltage to current
C) The relationship of volts and ohms
D) The product of voltage and current
Correct Answer: A
Rationale: Power factor = True Power (watts) / Apparent Power (volt-amperes). Low PF indicates
reactive loads like motors and transformers.
12. A 240V single-phase circuit supplies a 4800W electric water heater. What is the current draw?
A) 15A
B) 20A
