RESIDENTIAL ELECTRICIAN CERTIFICATION
EXAM | QUESTIONS AND ANSWERS | VERIFIED
ANSWERS PLUS RATIONALES | ALREADY GRADED
A+ | LATEST EXAM UPDATE
1. What is the standard voltage for most residential lighting circuits in the
United States?
A) 120 V
B) 240 V
C) 12 V
D) 208 V
Answer: A) 120 V — Most residential lighting circuits in the U.S. use
120 volts AC.
2. Which type of wire is typically used for residential branch circuits?
A) THHN
B) Romex (NM-B)
C) MC cable
D) BX cable
Answer: B) Romex (NM-B) — Non-metallic sheathed cable (NM-B) is
standard for indoor residential wiring.
3. What is the minimum wire gauge for a 20-amp residential circuit?
A) 14 AWG
B) 12 AWG
C) 10 AWG
D) 8 AWG
Answer: B) 12 AWG — 12-gauge copper wire is required for 20-amp
circuits to prevent overheating.
4. Which device is designed to protect people from electrical shock due to
ground faults?
A) Circuit breaker
B) Fuse
C) GFCI
D) AFCI
, Answer: C) GFCI — Ground Fault Circuit Interrupters detect ground
faults and shut off power to prevent shock.
5. In a 240 V split-phase system, how many hot wires are used?
A) 1
B) 2
C) 3
D) 4
Answer: B) 2 — A 240 V split-phase system uses two hot wires, each
120 V from neutral, combined for 240 V.
6. What is the NEC-required maximum spacing for receptacles in living
areas?
A) 6 ft
B) 12 ft
C) 10 ft
D) 4 ft
Answer: B) 12 ft — The National Electrical Code requires receptacles
no more than 12 feet apart along walls.
7. Which of the following is a function of a circuit breaker?
A) Provide continuous current
B) Protect wiring from overload
C) Transform voltage
D) Increase amperage
Answer: B) Protect wiring from overload — Circuit breakers interrupt
excessive current to prevent wire damage.
8. A standard residential circuit breaker trips at 100% of its rated current.
True or False?
Answer: False — Standard breakers are designed to handle slight
overloads briefly; they trip above rated current after a delay.
9. Which NEC article covers residential wiring methods?
A) Article 210
B) Article 250
C) Article 310
D) Article 400
Answer: A) Article 210 — NEC Article 210 details branch circuits for
dwelling units.
10. Aluminum wire in residential wiring requires:
A) No special treatment
, B) Anti-oxidant compound and proper connectors
C) Use only in 120 V circuits
D) Painting the wire
Answer: B) Anti-oxidant compound and proper connectors —
Aluminum wires oxidize and need special handling to prevent
overheating.
11. The purpose of an AFCI breaker is to:
A) Protect against short circuits
B) Protect against arcing faults
C) Regulate voltage
D) Reduce energy consumption
Answer: B) Protect against arcing faults — Arc Fault Circuit
Interrupters detect dangerous arcing that could cause fires.
12. The recommended height for wall receptacles above finished floor is:
A) 12 inches
B) 18 inches
C) 24 inches
D) 6 inches
Answer: A) 12 inches — Standard height for receptacles is 12 inches
above the finished floor.
13. Which type of conduit is commonly used outdoors for residential wiring?
A) EMT
B) PVC
C) NM-B
D) Romex
Answer: B) PVC — PVC conduit is weather-resistant and commonly
used for outdoor wiring.
14. What is the minimum size grounding electrode conductor for a 100-amp
service?
A) 8 AWG
B) 6 AWG
C) 4 AWG
D) 2 AWG
Answer: B) 6 AWG — According to the NEC, a 6 AWG copper
conductor is the minimum for a 100-amp service.
15. How many watts can a 15-amp, 120 V circuit safely supply?
A) 1200 W
, B) 1800 W
C) 1500 W
D) 1000 W
Answer: C) 1800 W — Power = Voltage × Current (120 V × 15 A = 1800
W). NEC recommends loading at 80%, so usable watts ~1440 W.
16. Which color wire is typically neutral in residential wiring?
A) Black
B) White
C) Red
D) Green
Answer: B) White — Neutral conductors are typically white.
17. Which wire color indicates grounding in residential wiring?
A) Black
B) Red
C) Green or bare
D) White
Answer: C) Green or bare — Ground wires are green or bare copper.
18. What is the standard spacing for smoke detectors in a residence?
A) One per floor
B) Every 30 ft
C) Inside each bedroom and hallway
D) Every 50 ft
Answer: C) Inside each bedroom and hallway — NEC requires smoke
alarms in bedrooms, outside sleeping areas, and each level.
19. Which tool is specifically designed to strip insulation from wires?
A) Pliers
B) Wire stripper
C) Multimeter
D) Hammer
Answer: B) Wire stripper — Wire strippers remove insulation without
damaging the conductor.
20. Which NEC article addresses grounding and bonding?
A) 200
B) 250
C) 300
D) 400
EXAM | QUESTIONS AND ANSWERS | VERIFIED
ANSWERS PLUS RATIONALES | ALREADY GRADED
A+ | LATEST EXAM UPDATE
1. What is the standard voltage for most residential lighting circuits in the
United States?
A) 120 V
B) 240 V
C) 12 V
D) 208 V
Answer: A) 120 V — Most residential lighting circuits in the U.S. use
120 volts AC.
2. Which type of wire is typically used for residential branch circuits?
A) THHN
B) Romex (NM-B)
C) MC cable
D) BX cable
Answer: B) Romex (NM-B) — Non-metallic sheathed cable (NM-B) is
standard for indoor residential wiring.
3. What is the minimum wire gauge for a 20-amp residential circuit?
A) 14 AWG
B) 12 AWG
C) 10 AWG
D) 8 AWG
Answer: B) 12 AWG — 12-gauge copper wire is required for 20-amp
circuits to prevent overheating.
4. Which device is designed to protect people from electrical shock due to
ground faults?
A) Circuit breaker
B) Fuse
C) GFCI
D) AFCI
, Answer: C) GFCI — Ground Fault Circuit Interrupters detect ground
faults and shut off power to prevent shock.
5. In a 240 V split-phase system, how many hot wires are used?
A) 1
B) 2
C) 3
D) 4
Answer: B) 2 — A 240 V split-phase system uses two hot wires, each
120 V from neutral, combined for 240 V.
6. What is the NEC-required maximum spacing for receptacles in living
areas?
A) 6 ft
B) 12 ft
C) 10 ft
D) 4 ft
Answer: B) 12 ft — The National Electrical Code requires receptacles
no more than 12 feet apart along walls.
7. Which of the following is a function of a circuit breaker?
A) Provide continuous current
B) Protect wiring from overload
C) Transform voltage
D) Increase amperage
Answer: B) Protect wiring from overload — Circuit breakers interrupt
excessive current to prevent wire damage.
8. A standard residential circuit breaker trips at 100% of its rated current.
True or False?
Answer: False — Standard breakers are designed to handle slight
overloads briefly; they trip above rated current after a delay.
9. Which NEC article covers residential wiring methods?
A) Article 210
B) Article 250
C) Article 310
D) Article 400
Answer: A) Article 210 — NEC Article 210 details branch circuits for
dwelling units.
10. Aluminum wire in residential wiring requires:
A) No special treatment
, B) Anti-oxidant compound and proper connectors
C) Use only in 120 V circuits
D) Painting the wire
Answer: B) Anti-oxidant compound and proper connectors —
Aluminum wires oxidize and need special handling to prevent
overheating.
11. The purpose of an AFCI breaker is to:
A) Protect against short circuits
B) Protect against arcing faults
C) Regulate voltage
D) Reduce energy consumption
Answer: B) Protect against arcing faults — Arc Fault Circuit
Interrupters detect dangerous arcing that could cause fires.
12. The recommended height for wall receptacles above finished floor is:
A) 12 inches
B) 18 inches
C) 24 inches
D) 6 inches
Answer: A) 12 inches — Standard height for receptacles is 12 inches
above the finished floor.
13. Which type of conduit is commonly used outdoors for residential wiring?
A) EMT
B) PVC
C) NM-B
D) Romex
Answer: B) PVC — PVC conduit is weather-resistant and commonly
used for outdoor wiring.
14. What is the minimum size grounding electrode conductor for a 100-amp
service?
A) 8 AWG
B) 6 AWG
C) 4 AWG
D) 2 AWG
Answer: B) 6 AWG — According to the NEC, a 6 AWG copper
conductor is the minimum for a 100-amp service.
15. How many watts can a 15-amp, 120 V circuit safely supply?
A) 1200 W
, B) 1800 W
C) 1500 W
D) 1000 W
Answer: C) 1800 W — Power = Voltage × Current (120 V × 15 A = 1800
W). NEC recommends loading at 80%, so usable watts ~1440 W.
16. Which color wire is typically neutral in residential wiring?
A) Black
B) White
C) Red
D) Green
Answer: B) White — Neutral conductors are typically white.
17. Which wire color indicates grounding in residential wiring?
A) Black
B) Red
C) Green or bare
D) White
Answer: C) Green or bare — Ground wires are green or bare copper.
18. What is the standard spacing for smoke detectors in a residence?
A) One per floor
B) Every 30 ft
C) Inside each bedroom and hallway
D) Every 50 ft
Answer: C) Inside each bedroom and hallway — NEC requires smoke
alarms in bedrooms, outside sleeping areas, and each level.
19. Which tool is specifically designed to strip insulation from wires?
A) Pliers
B) Wire stripper
C) Multimeter
D) Hammer
Answer: B) Wire stripper — Wire strippers remove insulation without
damaging the conductor.
20. Which NEC article addresses grounding and bonding?
A) 200
B) 250
C) 300
D) 400
