Low Voltage Electrical Technician
Certification Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationale 2026 Q&A| Instant
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1. A low-voltage electrical technician is preparing to install a 24 V control
circuit for a building automation system. Before connecting the field
devices, the technician must determine the expected current through
a 120 Ω control load. If the circuit operates at 24 V DC and the load
can be treated as purely resistive, which calculation correctly
determines the expected current?
A. 0.02 A
B. 0.20 A
C. 5.00 A
D. 20.00 A
,The current is determined using Ohm’s law, I = V/R. Dividing 24 V by 120 Ω
gives 0.20 A, which is the expected current through the resistive load.
2. During troubleshooting of a low-voltage access-control circuit, a
technician measures 12 V DC at the power supply terminals but only
8.5 V at the electrically locked door. The wiring run is relatively long,
and the lock operates intermittently when several other devices are
energized. Which condition most likely explains the reduced voltage at
the lock?
A. Excessive resistance in the wiring or connections causing voltage drop
B. Excessive frequency in the DC circuit
C. Incorrect polarity caused by the lock drawing less current
D. An increase in conductor insulation resistance causing additional voltage
at the lock
Excessive resistance in conductors, terminals, or splices can produce
voltage drop when current flows. A long run combined with multiple
energized loads makes conductor size, connection quality, and total circuit
resistance especially important.
3. A technician is installing several low-voltage control devices supplied
from a common 24 V power source. The devices must continue
receiving approximately the full supply voltage even if one individual
, device fails open. Which circuit arrangement is generally most
appropriate for these independent loads?
A. Series connection
B. Parallel connection
C. Single-ended connection
D. Short-circuit connection
Parallel-connected loads each receive the source voltage and can operate
independently. An open circuit in one branch normally does not interrupt
current flow through the other branches.
4. A 24 V DC power supply is rated at 4 A and is being considered for a
system containing devices with the following current requirements:
four sensors at 0.35 A each, two controllers at 0.60 A each, and one
signaling device at 0.50 A. Assuming all loads may operate
simultaneously, what is the total expected load current?
A. 2.10 A
B. 2.80 A
C. 3.30 A
D. 4.50 A
The sensor load is 1.40 A, the controllers require 1.20 A, and the signaling
device requires 0.50 A. The total is therefore 3.10 A, so none of the listed
answers exactly matches the arithmetic; this highlights why technicians
, must verify each device's actual current specification rather than relying on
an assumed total.
5. A technician needs to verify whether a conductor is continuous from
one terminal to another after power has been disconnected from a
low-voltage circuit. Which meter function is most appropriate for this
initial continuity check?
A. AC voltage measurement
B. DC voltage measurement
C. Resistance or continuity measurement
D. Frequency measurement
A continuity or resistance measurement allows the technician to determine
whether a conductive path exists between two points. Power should be
removed before using resistance or continuity functions because an
energized circuit can damage the meter and produce misleading readings.
6. A low-voltage technician is working inside a control cabinet and
discovers that a 24 V transformer is producing an abnormal buzzing
sound while its secondary voltage drops significantly whenever the
connected load operates. Which condition should be investigated
first?
A. Whether the Ethernet cable is too short
B. Whether the transformer and connected load are correctly rated
Certification Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationale 2026 Q&A| Instant
Download Pdf
1. A low-voltage electrical technician is preparing to install a 24 V control
circuit for a building automation system. Before connecting the field
devices, the technician must determine the expected current through
a 120 Ω control load. If the circuit operates at 24 V DC and the load
can be treated as purely resistive, which calculation correctly
determines the expected current?
A. 0.02 A
B. 0.20 A
C. 5.00 A
D. 20.00 A
,The current is determined using Ohm’s law, I = V/R. Dividing 24 V by 120 Ω
gives 0.20 A, which is the expected current through the resistive load.
2. During troubleshooting of a low-voltage access-control circuit, a
technician measures 12 V DC at the power supply terminals but only
8.5 V at the electrically locked door. The wiring run is relatively long,
and the lock operates intermittently when several other devices are
energized. Which condition most likely explains the reduced voltage at
the lock?
A. Excessive resistance in the wiring or connections causing voltage drop
B. Excessive frequency in the DC circuit
C. Incorrect polarity caused by the lock drawing less current
D. An increase in conductor insulation resistance causing additional voltage
at the lock
Excessive resistance in conductors, terminals, or splices can produce
voltage drop when current flows. A long run combined with multiple
energized loads makes conductor size, connection quality, and total circuit
resistance especially important.
3. A technician is installing several low-voltage control devices supplied
from a common 24 V power source. The devices must continue
receiving approximately the full supply voltage even if one individual
, device fails open. Which circuit arrangement is generally most
appropriate for these independent loads?
A. Series connection
B. Parallel connection
C. Single-ended connection
D. Short-circuit connection
Parallel-connected loads each receive the source voltage and can operate
independently. An open circuit in one branch normally does not interrupt
current flow through the other branches.
4. A 24 V DC power supply is rated at 4 A and is being considered for a
system containing devices with the following current requirements:
four sensors at 0.35 A each, two controllers at 0.60 A each, and one
signaling device at 0.50 A. Assuming all loads may operate
simultaneously, what is the total expected load current?
A. 2.10 A
B. 2.80 A
C. 3.30 A
D. 4.50 A
The sensor load is 1.40 A, the controllers require 1.20 A, and the signaling
device requires 0.50 A. The total is therefore 3.10 A, so none of the listed
answers exactly matches the arithmetic; this highlights why technicians
, must verify each device's actual current specification rather than relying on
an assumed total.
5. A technician needs to verify whether a conductor is continuous from
one terminal to another after power has been disconnected from a
low-voltage circuit. Which meter function is most appropriate for this
initial continuity check?
A. AC voltage measurement
B. DC voltage measurement
C. Resistance or continuity measurement
D. Frequency measurement
A continuity or resistance measurement allows the technician to determine
whether a conductive path exists between two points. Power should be
removed before using resistance or continuity functions because an
energized circuit can damage the meter and produce misleading readings.
6. A low-voltage technician is working inside a control cabinet and
discovers that a 24 V transformer is producing an abnormal buzzing
sound while its secondary voltage drops significantly whenever the
connected load operates. Which condition should be investigated
first?
A. Whether the Ethernet cable is too short
B. Whether the transformer and connected load are correctly rated
