LADWP COMMUNICATIONS ELECTRICIAN
EXAM — CLASS 3686 WITH QUESTIONS AND
VERIFIED ANSWERS, PLUS DETAILED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1. A Communications Electrician is troubleshooting a
communications cabinet that contains a DC power supply, radio
equipment, Ethernet switches, and control wiring. The equipment
has suddenly become unreliable, with multiple devices rebooting
intermittently. A preliminary measurement shows that the nominal
48-VDC supply is occasionally dropping substantially when several
transmitters activate. Which troubleshooting approach is MOST
appropriate?
A. Replace every communications device connected to the cabinet
because simultaneous failures indicate equipment damage
B. Increase the DC supply voltage above its rated value so that voltage
remains adequate during transmission
C. Verify the power source, protective devices, distribution conductors,
connections, grounding, and voltage under actual load before replacing
communications equipment
D. Disconnect the Ethernet network because digital communications
cannot function reliably when DC voltage fluctuates
Answer: C
Rationale: The electrician should first establish whether the common
power-distribution system is responsible for multiple symptoms.
Measuring voltage under actual load, checking connections and
protection, and tracing the power path can reveal voltage drop, loose
1
,terminations, inadequate capacity, or another common fault.
Replacing individual communications devices without establishing the
source of the problem is poor troubleshooting practice, while
deliberately raising equipment voltage beyond its rating can cause
additional damage.
2. A technician is terminating shielded communications cable. The
cable shield is intended to reduce electromagnetic interference, but
the technician discovers that the shield has been connected to
ground at several points along a long communications run. Under
certain conditions, unwanted current appears on the shield. What is
the PRIMARY concern?
A. The shield may become a substitute for the signal conductor
B. Multiple grounding points can create ground-loop currents and
introduce interference
C. Shielding always increases attenuation to an unacceptable level
D. Shielded cable cannot be used with digital communications
Answer: B
Rationale: A shield can provide valuable protection against
electromagnetic interference, but its grounding arrangement must be
compatible with the system design. Multiple unintended grounding
points can establish circulating currents when ground potentials
differ, potentially coupling noise into sensitive circuits. The correct
grounding method depends on the equipment, cable design, frequency,
and applicable engineering requirements; the electrician should follow
the approved system design rather than improvising a grounding
arrangement.
2
,3. A Communications Electrician is asked to diagnose a two-way
radio that receives transmissions clearly but produces no usable
transmitted audio. The transmitter keys normally and the RF
output indication appears normal. Which test sequence is MOST
logical?
A. Immediately replace the antenna
B. Start at the microphone/audio input and trace the transmit-audio path
toward the transmitter while confirming switching and modulation
functions
C. Replace the receiver because the system cannot transmit and receive
simultaneously
D. Increase transmitter power until audio becomes audible
Answer: B
Rationale: The symptom is highly localized: the transmitter keys and
appears to produce RF, but usable audio is absent. The technician
should therefore follow the transmit-audio path from the microphone
and associated wiring through audio processing, switching,
modulation, and transmitter circuitry. Replacing the antenna or
receiver without evidence is not a logical first step, and increasing RF
power does not correct a missing audio signal.
4. A microwave communications link between two facilities
experiences intermittent degradation whenever heavy electrical
equipment operates near one endpoint. Which factor should receive
PARTICULAR attention during troubleshooting?
A. Electromagnetic interference and grounding/bonding conditions
B. The color of the coaxial cable jacket
C. The number of employees using the remote facility
D. The telephone directory configuration
3
, Answer: A
Rationale: Intermittent communications degradation correlated with
operation of heavy electrical equipment strongly suggests a possible
electromagnetic-interference, grounding, bonding, shielding, or
power-quality issue. A disciplined technician would correlate the
interference with equipment operation, inspect cable routing and
grounding/bonding, examine power supplies and protection, and use
appropriate test instruments. The other choices have no meaningful
diagnostic relationship to the described symptom.
5. A fiber-optic communications circuit shows excessive optical loss
after maintenance. The transmitter and receiver both pass their
internal diagnostics. What should the electrician investigate FIRST?
A. Whether the fiber connectors are clean, properly seated, correctly
matched, and free of excessive bend or physical damage
B. Whether the Ethernet switch has a larger screen
C. Whether the fiber should be replaced with copper immediately
D. Whether the equipment rack should be painted
Answer: A
Rationale: Connector contamination, improper mating, damaged end
faces, excessive bending, poor splices, and physical damage are
common causes of unexpected optical loss. A technician should
inspect and test the optical path systematically rather than replacing
the entire medium immediately. Fiber systems require careful
handling because contamination that appears minor can significantly
affect optical performance.
6. A Communications Electrician is configuring an Ethernet switch
supporting a critical communications network. Two ports appear to
4
EXAM — CLASS 3686 WITH QUESTIONS AND
VERIFIED ANSWERS, PLUS DETAILED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
1. A Communications Electrician is troubleshooting a
communications cabinet that contains a DC power supply, radio
equipment, Ethernet switches, and control wiring. The equipment
has suddenly become unreliable, with multiple devices rebooting
intermittently. A preliminary measurement shows that the nominal
48-VDC supply is occasionally dropping substantially when several
transmitters activate. Which troubleshooting approach is MOST
appropriate?
A. Replace every communications device connected to the cabinet
because simultaneous failures indicate equipment damage
B. Increase the DC supply voltage above its rated value so that voltage
remains adequate during transmission
C. Verify the power source, protective devices, distribution conductors,
connections, grounding, and voltage under actual load before replacing
communications equipment
D. Disconnect the Ethernet network because digital communications
cannot function reliably when DC voltage fluctuates
Answer: C
Rationale: The electrician should first establish whether the common
power-distribution system is responsible for multiple symptoms.
Measuring voltage under actual load, checking connections and
protection, and tracing the power path can reveal voltage drop, loose
1
,terminations, inadequate capacity, or another common fault.
Replacing individual communications devices without establishing the
source of the problem is poor troubleshooting practice, while
deliberately raising equipment voltage beyond its rating can cause
additional damage.
2. A technician is terminating shielded communications cable. The
cable shield is intended to reduce electromagnetic interference, but
the technician discovers that the shield has been connected to
ground at several points along a long communications run. Under
certain conditions, unwanted current appears on the shield. What is
the PRIMARY concern?
A. The shield may become a substitute for the signal conductor
B. Multiple grounding points can create ground-loop currents and
introduce interference
C. Shielding always increases attenuation to an unacceptable level
D. Shielded cable cannot be used with digital communications
Answer: B
Rationale: A shield can provide valuable protection against
electromagnetic interference, but its grounding arrangement must be
compatible with the system design. Multiple unintended grounding
points can establish circulating currents when ground potentials
differ, potentially coupling noise into sensitive circuits. The correct
grounding method depends on the equipment, cable design, frequency,
and applicable engineering requirements; the electrician should follow
the approved system design rather than improvising a grounding
arrangement.
2
,3. A Communications Electrician is asked to diagnose a two-way
radio that receives transmissions clearly but produces no usable
transmitted audio. The transmitter keys normally and the RF
output indication appears normal. Which test sequence is MOST
logical?
A. Immediately replace the antenna
B. Start at the microphone/audio input and trace the transmit-audio path
toward the transmitter while confirming switching and modulation
functions
C. Replace the receiver because the system cannot transmit and receive
simultaneously
D. Increase transmitter power until audio becomes audible
Answer: B
Rationale: The symptom is highly localized: the transmitter keys and
appears to produce RF, but usable audio is absent. The technician
should therefore follow the transmit-audio path from the microphone
and associated wiring through audio processing, switching,
modulation, and transmitter circuitry. Replacing the antenna or
receiver without evidence is not a logical first step, and increasing RF
power does not correct a missing audio signal.
4. A microwave communications link between two facilities
experiences intermittent degradation whenever heavy electrical
equipment operates near one endpoint. Which factor should receive
PARTICULAR attention during troubleshooting?
A. Electromagnetic interference and grounding/bonding conditions
B. The color of the coaxial cable jacket
C. The number of employees using the remote facility
D. The telephone directory configuration
3
, Answer: A
Rationale: Intermittent communications degradation correlated with
operation of heavy electrical equipment strongly suggests a possible
electromagnetic-interference, grounding, bonding, shielding, or
power-quality issue. A disciplined technician would correlate the
interference with equipment operation, inspect cable routing and
grounding/bonding, examine power supplies and protection, and use
appropriate test instruments. The other choices have no meaningful
diagnostic relationship to the described symptom.
5. A fiber-optic communications circuit shows excessive optical loss
after maintenance. The transmitter and receiver both pass their
internal diagnostics. What should the electrician investigate FIRST?
A. Whether the fiber connectors are clean, properly seated, correctly
matched, and free of excessive bend or physical damage
B. Whether the Ethernet switch has a larger screen
C. Whether the fiber should be replaced with copper immediately
D. Whether the equipment rack should be painted
Answer: A
Rationale: Connector contamination, improper mating, damaged end
faces, excessive bending, poor splices, and physical damage are
common causes of unexpected optical loss. A technician should
inspect and test the optical path systematically rather than replacing
the entire medium immediately. Fiber systems require careful
handling because contamination that appears minor can significantly
affect optical performance.
6. A Communications Electrician is configuring an Ethernet switch
supporting a critical communications network. Two ports appear to
4
