BCIT Electrical Apprenticeship Level 3 Exam
Questions with Correct Answers
(VerifiedAnswers) Plus Rationales 2026 Q&A
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1. In a balanced three-phase wye-connected system, what is
the relationship between line voltage and phase voltage?
A. Line voltage equals phase voltage
B. Line voltage is half the phase voltage
C. Line voltage is √3 times the phase voltage
D. Line voltage is three times the phase voltage
In a balanced wye system, each phase winding is connected
between a line conductor and the neutral point. The line-to-line
voltage is the vector difference between two phase voltages.
Because those voltages are separated by 120°, the magnitude
of the line voltage is √3 times the phase voltage. Therefore, a
120 V phase voltage produces approximately 208 V line voltage.
2. What is the primary purpose of a motor overload relay?
A. Protect the motor against short circuits only
B. Protect the branch-circuit conductors from lightning
,C. Protect the motor against sustained overload conditions
D. Increase the motor's starting torque
An overload relay responds to excessive motor current over a
period of time. It is intended to protect the motor from
overheating caused by conditions such as mechanical overload,
low voltage, or loss of cooling. Short-circuit protection is
normally provided separately by an overcurrent protective
device.
3. A 600 V three-phase motor draws 20 A at a power factor of
0.85. Approximately what real power does it consume?
A. 10.2 kW
B. 17.7 kW
C. 20.4 kW
D. 30.6 kW
For a balanced three-phase load, real power is calculated using
P = √3 × VL × IL × PF. Substituting 600 V, 20 A, and 0.85 gives
approximately 17,668 W, or 17.7 kW. The power factor must be
included because not all apparent power is converted into real
power.
,4. What happens to the synchronous speed of an induction
motor when the supply frequency is increased while the
number of poles remains constant?
A. It decreases
B. It remains unchanged
C. It increases
D. It becomes zero
The synchronous speed of an AC motor is determined by Ns =
120f/P. With the number of poles fixed, increasing frequency
directly increases synchronous speed. This relationship is
fundamental to variable-frequency-drive applications.
5. What is the main purpose of bonding normally non-current-
carrying metal parts of electrical equipment?
A. Increase operating voltage
B. Improve power factor
C. Provide a low-impedance path for fault current
D. Reduce normal load current
Bonding connects exposed conductive parts together and to the
grounding system so that a fault involving metal equipment
enclosures can produce sufficient current to operate the
overcurrent protective device. This helps limit the duration of
dangerous touch voltage.
, 6. A transformer has 600 V on its primary and 120 V on its
secondary. What is the approximate turns ratio from primary
to secondary?
A. 1:1
B. 2:1
C. 5:1
D. 10:1
For an ideal transformer, the voltage ratio is proportional to the
turns ratio. Dividing 600 V by 120 V gives 5, so the primary has
approximately five times as many turns as the secondary. This
makes the transformer a step-down transformer.
7. What is the main function of a contactor in a motor-control
circuit?
A. Measure insulation resistance
B. Convert AC into DC
C. Switch power to a load using an electrically controlled
mechanism
D. Provide mechanical overload protection
A contactor uses an electromagnetic coil to operate contacts
capable of switching relatively high currents. The control circuit
Questions with Correct Answers
(VerifiedAnswers) Plus Rationales 2026 Q&A
Instant Download PDF
1. In a balanced three-phase wye-connected system, what is
the relationship between line voltage and phase voltage?
A. Line voltage equals phase voltage
B. Line voltage is half the phase voltage
C. Line voltage is √3 times the phase voltage
D. Line voltage is three times the phase voltage
In a balanced wye system, each phase winding is connected
between a line conductor and the neutral point. The line-to-line
voltage is the vector difference between two phase voltages.
Because those voltages are separated by 120°, the magnitude
of the line voltage is √3 times the phase voltage. Therefore, a
120 V phase voltage produces approximately 208 V line voltage.
2. What is the primary purpose of a motor overload relay?
A. Protect the motor against short circuits only
B. Protect the branch-circuit conductors from lightning
,C. Protect the motor against sustained overload conditions
D. Increase the motor's starting torque
An overload relay responds to excessive motor current over a
period of time. It is intended to protect the motor from
overheating caused by conditions such as mechanical overload,
low voltage, or loss of cooling. Short-circuit protection is
normally provided separately by an overcurrent protective
device.
3. A 600 V three-phase motor draws 20 A at a power factor of
0.85. Approximately what real power does it consume?
A. 10.2 kW
B. 17.7 kW
C. 20.4 kW
D. 30.6 kW
For a balanced three-phase load, real power is calculated using
P = √3 × VL × IL × PF. Substituting 600 V, 20 A, and 0.85 gives
approximately 17,668 W, or 17.7 kW. The power factor must be
included because not all apparent power is converted into real
power.
,4. What happens to the synchronous speed of an induction
motor when the supply frequency is increased while the
number of poles remains constant?
A. It decreases
B. It remains unchanged
C. It increases
D. It becomes zero
The synchronous speed of an AC motor is determined by Ns =
120f/P. With the number of poles fixed, increasing frequency
directly increases synchronous speed. This relationship is
fundamental to variable-frequency-drive applications.
5. What is the main purpose of bonding normally non-current-
carrying metal parts of electrical equipment?
A. Increase operating voltage
B. Improve power factor
C. Provide a low-impedance path for fault current
D. Reduce normal load current
Bonding connects exposed conductive parts together and to the
grounding system so that a fault involving metal equipment
enclosures can produce sufficient current to operate the
overcurrent protective device. This helps limit the duration of
dangerous touch voltage.
, 6. A transformer has 600 V on its primary and 120 V on its
secondary. What is the approximate turns ratio from primary
to secondary?
A. 1:1
B. 2:1
C. 5:1
D. 10:1
For an ideal transformer, the voltage ratio is proportional to the
turns ratio. Dividing 600 V by 120 V gives 5, so the primary has
approximately five times as many turns as the secondary. This
makes the transformer a step-down transformer.
7. What is the main function of a contactor in a motor-control
circuit?
A. Measure insulation resistance
B. Convert AC into DC
C. Switch power to a load using an electrically controlled
mechanism
D. Provide mechanical overload protection
A contactor uses an electromagnetic coil to operate contacts
capable of switching relatively high currents. The control circuit
