NYC DCAS Electrician Exam Questions with Correct Answers
(Verified Answers) Plus Rationales -2026 Update Q&A
Question 1
What is the primary purpose of a circuit breaker?
A. Increase circuit voltage
B. Protect conductors from excessive current
C. Improve power factor
D. Store electrical energy
Correct Answer: B. Protect conductors from excessive current
Rationale: A circuit breaker opens the circuit when current becomes
dangerously high because of an overload or short circuit. This protects
conductors and connected equipment from overheating and possible fire. A
breaker does not normally increase voltage or store energy.
Question 2
According to Ohm's law, which formula is correct?
A. V = I × R
B. V = I ÷ R
C. R = V × I
D. I = V × R
Correct Answer: A. V = I × R
Rationale: Ohm's law states that voltage equals current multiplied by
resistance. The relationship can also be rearranged to calculate current or
resistance: I = V/R and R = V/I.
Question 3
pg. 1
,A 120-volt circuit supplies a 10-ohm load. Approximately how much current
flows?
A. 1.2 A
B. 10 A
C. 12 A
D. 120 A
Correct Answer: C. 12 A
Rationale: Using I = V/R, the current is 120 ÷ 10 = 12 amperes.
Understanding this relationship is fundamental when calculating circuit
loading and selecting appropriate conductors and overcurrent protection.
Question 4
What happens to total resistance when resistors are connected in series?
A. It becomes zero
B. It is equal to the largest resistor only
C. The resistances add together
D. It is always less than the smallest resistor
Correct Answer: C. The resistances add together
Rationale: In a series circuit, total resistance is the sum of all individual
resistances. For example, 5 Ω + 10 Ω + 15 Ω equals 30 Ω. Increasing
resistance reduces current when the supply voltage remains constant.
Question 5
In a parallel circuit, the voltage across each properly connected branch is
generally:
A. Zero
B. The same as the source voltage
pg. 2
,C. Different in every branch
D. Twice the source voltage
Correct Answer: B. The same as the source voltage
Rationale: Parallel branches are connected across the same two electrical
points, so each branch receives the source voltage. The current divides among
the branches according to their individual impedances or resistances.
Question 6
Which instrument is normally used to measure current without disconnecting
a conductor?
A. Clamp meter
B. Megohmmeter
C. Ohmmeter
D. Phase-sequence indicator
Correct Answer: A. Clamp meter
Rationale: A clamp meter measures current by sensing the magnetic field
surrounding a conductor. This allows an electrician to measure current
without opening the circuit. Proper technique is important because clamping
around multiple conductors can cause the magnetic fields to cancel.
Question 7
What should normally be done before measuring resistance with an
ohmmeter?
A. Increase circuit voltage
B. Energize the circuit
C. De-energize the circuit
D. Connect the meter across a transformer primary while energized
Correct Answer: C. De-energize the circuit
pg. 3
, Rationale: Resistance measurements are normally made on de-energized
circuits. Applying external voltage while using an ohmmeter can produce
incorrect readings and may damage the instrument or create a shock hazard.
Question 8
What is the primary purpose of grounding electrical equipment?
A. Increase resistance
B. Provide a path for fault current and reduce shock risk
C. Increase normal operating current
D. Eliminate all circuit voltage
Correct Answer: B. Provide a path for fault current and reduce shock risk
Rationale: Grounding and bonding help establish a low-impedance path for
fault current so protective devices can operate promptly. They are important
components of electrical safety and are not intended to carry normal load
current in the equipment grounding path.
Question 9
What is bonding primarily intended to accomplish?
A. Keep conductive parts at substantially the same electrical potential
B. Increase motor speed
C. Reduce conductor size
D. Increase line voltage
Correct Answer: A. Keep conductive parts at substantially the same
electrical potential
Rationale: Bonding electrically connects normally non-current-carrying
conductive parts so that, during a fault, they have a reliable path for fault
current and do not develop dangerous differences in potential.
pg. 4
(Verified Answers) Plus Rationales -2026 Update Q&A
Question 1
What is the primary purpose of a circuit breaker?
A. Increase circuit voltage
B. Protect conductors from excessive current
C. Improve power factor
D. Store electrical energy
Correct Answer: B. Protect conductors from excessive current
Rationale: A circuit breaker opens the circuit when current becomes
dangerously high because of an overload or short circuit. This protects
conductors and connected equipment from overheating and possible fire. A
breaker does not normally increase voltage or store energy.
Question 2
According to Ohm's law, which formula is correct?
A. V = I × R
B. V = I ÷ R
C. R = V × I
D. I = V × R
Correct Answer: A. V = I × R
Rationale: Ohm's law states that voltage equals current multiplied by
resistance. The relationship can also be rearranged to calculate current or
resistance: I = V/R and R = V/I.
Question 3
pg. 1
,A 120-volt circuit supplies a 10-ohm load. Approximately how much current
flows?
A. 1.2 A
B. 10 A
C. 12 A
D. 120 A
Correct Answer: C. 12 A
Rationale: Using I = V/R, the current is 120 ÷ 10 = 12 amperes.
Understanding this relationship is fundamental when calculating circuit
loading and selecting appropriate conductors and overcurrent protection.
Question 4
What happens to total resistance when resistors are connected in series?
A. It becomes zero
B. It is equal to the largest resistor only
C. The resistances add together
D. It is always less than the smallest resistor
Correct Answer: C. The resistances add together
Rationale: In a series circuit, total resistance is the sum of all individual
resistances. For example, 5 Ω + 10 Ω + 15 Ω equals 30 Ω. Increasing
resistance reduces current when the supply voltage remains constant.
Question 5
In a parallel circuit, the voltage across each properly connected branch is
generally:
A. Zero
B. The same as the source voltage
pg. 2
,C. Different in every branch
D. Twice the source voltage
Correct Answer: B. The same as the source voltage
Rationale: Parallel branches are connected across the same two electrical
points, so each branch receives the source voltage. The current divides among
the branches according to their individual impedances or resistances.
Question 6
Which instrument is normally used to measure current without disconnecting
a conductor?
A. Clamp meter
B. Megohmmeter
C. Ohmmeter
D. Phase-sequence indicator
Correct Answer: A. Clamp meter
Rationale: A clamp meter measures current by sensing the magnetic field
surrounding a conductor. This allows an electrician to measure current
without opening the circuit. Proper technique is important because clamping
around multiple conductors can cause the magnetic fields to cancel.
Question 7
What should normally be done before measuring resistance with an
ohmmeter?
A. Increase circuit voltage
B. Energize the circuit
C. De-energize the circuit
D. Connect the meter across a transformer primary while energized
Correct Answer: C. De-energize the circuit
pg. 3
, Rationale: Resistance measurements are normally made on de-energized
circuits. Applying external voltage while using an ohmmeter can produce
incorrect readings and may damage the instrument or create a shock hazard.
Question 8
What is the primary purpose of grounding electrical equipment?
A. Increase resistance
B. Provide a path for fault current and reduce shock risk
C. Increase normal operating current
D. Eliminate all circuit voltage
Correct Answer: B. Provide a path for fault current and reduce shock risk
Rationale: Grounding and bonding help establish a low-impedance path for
fault current so protective devices can operate promptly. They are important
components of electrical safety and are not intended to carry normal load
current in the equipment grounding path.
Question 9
What is bonding primarily intended to accomplish?
A. Keep conductive parts at substantially the same electrical potential
B. Increase motor speed
C. Reduce conductor size
D. Increase line voltage
Correct Answer: A. Keep conductive parts at substantially the same
electrical potential
Rationale: Bonding electrically connects normally non-current-carrying
conductive parts so that, during a fault, they have a reliable path for fault
current and do not develop dangerous differences in potential.
pg. 4
