Texas Residential Wireman Certification Exam
Prep 2026 – Practice Questions, Answers &
Detailed Rationales
1. What is the minimum grounding electrode conductor size for a residential service with 200A
service conductors?
A. #6 copper
B. #4 copper
C. #4 copper
D. #8 copper
The grounding electrode conductor size is based on NEC Table 250.66, which requires #4 copper for
service conductors up to 200A using typical residential conductor sizing.
2. Which device provides protection against arc-faults in dwelling unit bedrooms?
A. GFCI breaker
B. Standard breaker
C. AFCI breaker
D. Thermal relay
Arc-Fault Circuit Interrupters are required in dwelling unit bedrooms to reduce fire risk from arcing
faults per NEC 210.12.
3. The maximum number of 14 AWG copper conductors allowed in a 2-inch EMT conduit is
determined by:
A. Voltage drop
B. Fill percentage rules
C. Ambient temperature
D. Conductor insulation type
Conduit fill is determined by NEC Chapter 9, Table 1 and associated conduit fill tables.
4. What is the minimum clearance of overhead service conductors above a residential driveway?
A. 10 feet
B. 12 feet
C. 12 feet
D. 8 feet
NEC 230.24 requires at least 12 feet clearance over residential driveways.
,5. A GFCI trips when:
A. Voltage is too high
B. Current is balanced
C. Current leakage is detected to ground
D. Overcurrent occurs
GFCIs monitor imbalance between hot and neutral conductors and trip when leakage is detected.
6. Which wire is typically used as the equipment grounding conductor in residential NM cable?
A. White
B. Red
C. Bare copper
D. Blue
NM cable includes a bare copper grounding conductor for equipment grounding.
7. The minimum burial depth for residential UF cable without protection is:
A. 6 inches
B. 12 inches
C. 24 inches
D. 18 inches
NEC Table 300.5 requires 24 inches cover for UF cable without additional protection.
8. A 3-way switch is used to:
A. Control a load from one location
B. Control two loads
C. Control a load from two locations
D. Dim lighting
3-way switches allow control of a load from two separate locations.
9. The purpose of a neutral conductor is to:
A. Carry fault current only
B. Ground equipment
C. Carry return current in a circuit
D. Increase voltage
The neutral provides a return path for current back to the source.
10. What is the maximum number of 15A receptacles on a residential general lighting circuit?
A. 5
B. 10
C. Determined by load calculation
, D. 20
NEC does not set a fixed number; load calculation determines circuit sizing.
11. EMT conduit is commonly made of:
A. PVC
B. Aluminum only
C. Galvanized steel
D. Rubber
EMT is thin-wall galvanized steel tubing used for electrical wiring.
12. The standard voltage for residential branch circuits in Texas is:
A. 120V only
B. 240V only
C. 120/240V single-phase
D. 277/480V
Residential systems typically use split-phase 120/240V service.
13. The purpose of a breaker is to:
A. Increase voltage
B. Protect against overcurrent
C. Store energy
D. Ground a system
Breakers open a circuit when excessive current is detected.
14. A receptacle installed near a kitchen sink must be:
A. Standard type
B. AFCI protected only
C. GFCI protected
D. 240V rated
NEC requires GFCI protection in kitchen countertop areas.
15. NM cable is commonly referred to as:
A. MC cable
B. BX cable
C. Romex
D. THHN
NM-B cable is commonly known as Romex in residential wiring.
Prep 2026 – Practice Questions, Answers &
Detailed Rationales
1. What is the minimum grounding electrode conductor size for a residential service with 200A
service conductors?
A. #6 copper
B. #4 copper
C. #4 copper
D. #8 copper
The grounding electrode conductor size is based on NEC Table 250.66, which requires #4 copper for
service conductors up to 200A using typical residential conductor sizing.
2. Which device provides protection against arc-faults in dwelling unit bedrooms?
A. GFCI breaker
B. Standard breaker
C. AFCI breaker
D. Thermal relay
Arc-Fault Circuit Interrupters are required in dwelling unit bedrooms to reduce fire risk from arcing
faults per NEC 210.12.
3. The maximum number of 14 AWG copper conductors allowed in a 2-inch EMT conduit is
determined by:
A. Voltage drop
B. Fill percentage rules
C. Ambient temperature
D. Conductor insulation type
Conduit fill is determined by NEC Chapter 9, Table 1 and associated conduit fill tables.
4. What is the minimum clearance of overhead service conductors above a residential driveway?
A. 10 feet
B. 12 feet
C. 12 feet
D. 8 feet
NEC 230.24 requires at least 12 feet clearance over residential driveways.
,5. A GFCI trips when:
A. Voltage is too high
B. Current is balanced
C. Current leakage is detected to ground
D. Overcurrent occurs
GFCIs monitor imbalance between hot and neutral conductors and trip when leakage is detected.
6. Which wire is typically used as the equipment grounding conductor in residential NM cable?
A. White
B. Red
C. Bare copper
D. Blue
NM cable includes a bare copper grounding conductor for equipment grounding.
7. The minimum burial depth for residential UF cable without protection is:
A. 6 inches
B. 12 inches
C. 24 inches
D. 18 inches
NEC Table 300.5 requires 24 inches cover for UF cable without additional protection.
8. A 3-way switch is used to:
A. Control a load from one location
B. Control two loads
C. Control a load from two locations
D. Dim lighting
3-way switches allow control of a load from two separate locations.
9. The purpose of a neutral conductor is to:
A. Carry fault current only
B. Ground equipment
C. Carry return current in a circuit
D. Increase voltage
The neutral provides a return path for current back to the source.
10. What is the maximum number of 15A receptacles on a residential general lighting circuit?
A. 5
B. 10
C. Determined by load calculation
, D. 20
NEC does not set a fixed number; load calculation determines circuit sizing.
11. EMT conduit is commonly made of:
A. PVC
B. Aluminum only
C. Galvanized steel
D. Rubber
EMT is thin-wall galvanized steel tubing used for electrical wiring.
12. The standard voltage for residential branch circuits in Texas is:
A. 120V only
B. 240V only
C. 120/240V single-phase
D. 277/480V
Residential systems typically use split-phase 120/240V service.
13. The purpose of a breaker is to:
A. Increase voltage
B. Protect against overcurrent
C. Store energy
D. Ground a system
Breakers open a circuit when excessive current is detected.
14. A receptacle installed near a kitchen sink must be:
A. Standard type
B. AFCI protected only
C. GFCI protected
D. 240V rated
NEC requires GFCI protection in kitchen countertop areas.
15. NM cable is commonly referred to as:
A. MC cable
B. BX cable
C. Romex
D. THHN
NM-B cable is commonly known as Romex in residential wiring.
