Texas Master Electrician Exam Practice
Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. A master electrician is reviewing plans for a commercial building
where the service conductors will supply a calculated load of 380
amperes continuous and 120 amperes noncontinuous at 480/277
volts, three-phase. According to the National Electrical Code
requirements for sizing service conductors, what is the minimum
ampacity required for the service conductors before adjustment or
correction factors are applied?
A. 380 amperes
B. 425 amperes
C. 595 amperes
D. 625 amperes
,Rationale: Continuous loads must be multiplied by 125 percent before
being added to noncontinuous loads. Therefore, 380 × 1.25 = 475 amperes,
and 475 + 120 = 595 amperes minimum conductor ampacity required.
2. In a hazardous location classified as Class I, Division 1, which wiring
method is generally permitted for exposed aboveground installations
involving rigid raceway systems intended to contain explosions and
prevent ignition of surrounding atmospheres?
A. Electrical metallic tubing with compression fittings
B. Type NM cable in conduit
C. Threaded rigid metal conduit with approved explosionproof fittings
D. Flexible nonmetallic conduit with gasketed couplings
Rationale: Class I, Division 1 locations require wiring methods capable of
containing internal explosions. Threaded rigid metal conduit with
explosionproof fittings is specifically designed and approved for such
hazardous environments.
3. A separately derived system transformer has a secondary voltage of
208Y/120 volts supplying a commercial occupancy. Where must the
system bonding jumper generally be installed according to NEC
grounding requirements?
A. At the first panelboard only
B. At the branch-circuit disconnecting means
,C. At the source of the separately derived system or first disconnecting
means
D. Only at the grounding electrode conductor termination point outdoors
Rationale: NEC rules permit the system bonding jumper to be installed
either at the source of the separately derived system or at the first
disconnecting means, depending on installation conditions and compliance
requirements.
4. An electrician measures voltage drop on a 240-volt feeder and finds
that the load-end voltage is 228 volts while carrying rated current.
What percentage voltage drop exists on the feeder?
A. 2 percent
B. 3 percent
C. 5 percent
D. 7 percent
Rationale: Voltage drop percentage equals the voltage lost divided by
system voltage. The drop is 240 − 228 = 12 volts. Then 12 ÷ 240 × 100 = 5
percent.
5. Which motor controller feature is specifically intended to provide
protection against prolonged motor overload conditions rather than
short-circuit or ground-fault conditions?
, A. Instantaneous trip breaker
B. Motor branch-circuit short-circuit protector
C. Time-delay fuse
D. Overload relay assembly
Rationale: Overload relays are designed to protect motors against
overheating caused by overloads and extended overcurrent conditions,
whereas short-circuit protection devices respond to fault currents.
6. In a healthcare facility classified as a Category 1 essential electrical
system, what branch of the essential electrical system supplies power
to life safety functions such as egress lighting and fire alarms?
A. Equipment branch
B. Critical branch
C. Isolated power branch
D. Life safety branch
Rationale: The life safety branch supplies circuits essential to patient and
staff safety, including illumination of exits, alarm systems, and
communications necessary during emergencies.
7. A feeder conductor supplying a continuous load only has an actual
load current of 160 amperes. What minimum conductor ampacity
must be selected before ambient temperature corrections?
Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. A master electrician is reviewing plans for a commercial building
where the service conductors will supply a calculated load of 380
amperes continuous and 120 amperes noncontinuous at 480/277
volts, three-phase. According to the National Electrical Code
requirements for sizing service conductors, what is the minimum
ampacity required for the service conductors before adjustment or
correction factors are applied?
A. 380 amperes
B. 425 amperes
C. 595 amperes
D. 625 amperes
,Rationale: Continuous loads must be multiplied by 125 percent before
being added to noncontinuous loads. Therefore, 380 × 1.25 = 475 amperes,
and 475 + 120 = 595 amperes minimum conductor ampacity required.
2. In a hazardous location classified as Class I, Division 1, which wiring
method is generally permitted for exposed aboveground installations
involving rigid raceway systems intended to contain explosions and
prevent ignition of surrounding atmospheres?
A. Electrical metallic tubing with compression fittings
B. Type NM cable in conduit
C. Threaded rigid metal conduit with approved explosionproof fittings
D. Flexible nonmetallic conduit with gasketed couplings
Rationale: Class I, Division 1 locations require wiring methods capable of
containing internal explosions. Threaded rigid metal conduit with
explosionproof fittings is specifically designed and approved for such
hazardous environments.
3. A separately derived system transformer has a secondary voltage of
208Y/120 volts supplying a commercial occupancy. Where must the
system bonding jumper generally be installed according to NEC
grounding requirements?
A. At the first panelboard only
B. At the branch-circuit disconnecting means
,C. At the source of the separately derived system or first disconnecting
means
D. Only at the grounding electrode conductor termination point outdoors
Rationale: NEC rules permit the system bonding jumper to be installed
either at the source of the separately derived system or at the first
disconnecting means, depending on installation conditions and compliance
requirements.
4. An electrician measures voltage drop on a 240-volt feeder and finds
that the load-end voltage is 228 volts while carrying rated current.
What percentage voltage drop exists on the feeder?
A. 2 percent
B. 3 percent
C. 5 percent
D. 7 percent
Rationale: Voltage drop percentage equals the voltage lost divided by
system voltage. The drop is 240 − 228 = 12 volts. Then 12 ÷ 240 × 100 = 5
percent.
5. Which motor controller feature is specifically intended to provide
protection against prolonged motor overload conditions rather than
short-circuit or ground-fault conditions?
, A. Instantaneous trip breaker
B. Motor branch-circuit short-circuit protector
C. Time-delay fuse
D. Overload relay assembly
Rationale: Overload relays are designed to protect motors against
overheating caused by overloads and extended overcurrent conditions,
whereas short-circuit protection devices respond to fault currents.
6. In a healthcare facility classified as a Category 1 essential electrical
system, what branch of the essential electrical system supplies power
to life safety functions such as egress lighting and fire alarms?
A. Equipment branch
B. Critical branch
C. Isolated power branch
D. Life safety branch
Rationale: The life safety branch supplies circuits essential to patient and
staff safety, including illumination of exits, alarm systems, and
communications necessary during emergencies.
7. A feeder conductor supplying a continuous load only has an actual
load current of 160 amperes. What minimum conductor ampacity
must be selected before ambient temperature corrections?
