Solution and Answer Guide
Illustrated Guide to the National
Electrical Code 9th Edition
1. Which of the following is the primary purpose of the National Electrical Code
(NEC)?
A) To specify the materials used in electrical installations
B) To establish guidelines for electrical installations to ensure safety
C) To provide instructions for the operation of electrical equipment
D) To regulate the installation of electrical systems in residential buildings
Answer: B) To establish guidelines for electrical installations to ensure safety
2. According to the NEC, what is the minimum height for an electrical panel installed
in a residential garage?
A) 4 feet above the floor
B) 5 feet above the floor
C) 6 feet above the floor
D) 7 feet above the floor
Answer: D) 7 feet above the floor
3. What type of conductor insulation is typically required for use in a wet location?
A) THHN
B) THWN
C) XHHW
D) USE
,Answer: B) THWN
4. In a residential electrical system, which of the following is the primary function of
a GFCI outlet?
A) To prevent overload conditions
B) To protect against short circuits
C) To provide ground fault protection
D) To reduce electromagnetic interference
Answer: C) To provide ground fault protection
5. What is the maximum number of 14 AWG conductors allowed in a 1/2-inch
conduit according to NEC guidelines?
A) 4
B) 6
C) 9
D) 12
Answer: B) 6
6. What is the purpose of a bonding jumper in an electrical system?
A) To connect the neutral and ground conductors
B) To ensure continuity between different metal parts
C) To isolate the electrical system from the earth
D) To increase the voltage supply to the circuit
Answer: B) To ensure continuity between different metal parts
,7. According to the NEC, how far should a lighting outlet be placed from the edge of
a bathtub?
A) 3 feet
B) 4 feet
C) 6 feet
D) 8 feet
Answer: C) 6 feet
8. What is the required minimum grounding conductor size for a 100-amp residential
service according to NEC?
A) 8 AWG
B) 6 AWG
C) 4 AWG
D) 2 AWG
Answer: B) 6 AWG
9. When installing a subpanel, what is the correct method for connecting the neutral
and ground wires?
A) Bond the neutral and ground wires in the subpanel
B) Separate the neutral and ground wires in the subpanel
C) Connect the neutral wire to the ground wire in the main panel
D) Connect the neutral and ground wires together at the meter
Answer: B) Separate the neutral and ground wires in the subpanel
10. What is the maximum allowable voltage drop for a feeder circuit according to
NEC guidelines?
, A) 2%
B) 4%
C) 6%
D) 8%
Answer: B) 4%
11. What is the minimum size conduit required for a group of 3 conductors of 12
AWG according to NEC?
A) 1/2 inch
B) 3/4 inch
C) 1 inch
D) 1 1/4 inch
Answer: A) 1/2 inch
12. In which of the following situations is a double-pole circuit breaker required?
A) For a 240-volt circuit
B) For a 120-volt circuit
C) For a 277-volt circuit
D) For a 480-volt circuit
Answer: A) For a 240-volt circuit
13. According to the NEC, which type of box is required for an outdoor location
exposed to weather?
A) Plastic box
B) Metal box with weatherproof cover
Illustrated Guide to the National
Electrical Code 9th Edition
1. Which of the following is the primary purpose of the National Electrical Code
(NEC)?
A) To specify the materials used in electrical installations
B) To establish guidelines for electrical installations to ensure safety
C) To provide instructions for the operation of electrical equipment
D) To regulate the installation of electrical systems in residential buildings
Answer: B) To establish guidelines for electrical installations to ensure safety
2. According to the NEC, what is the minimum height for an electrical panel installed
in a residential garage?
A) 4 feet above the floor
B) 5 feet above the floor
C) 6 feet above the floor
D) 7 feet above the floor
Answer: D) 7 feet above the floor
3. What type of conductor insulation is typically required for use in a wet location?
A) THHN
B) THWN
C) XHHW
D) USE
,Answer: B) THWN
4. In a residential electrical system, which of the following is the primary function of
a GFCI outlet?
A) To prevent overload conditions
B) To protect against short circuits
C) To provide ground fault protection
D) To reduce electromagnetic interference
Answer: C) To provide ground fault protection
5. What is the maximum number of 14 AWG conductors allowed in a 1/2-inch
conduit according to NEC guidelines?
A) 4
B) 6
C) 9
D) 12
Answer: B) 6
6. What is the purpose of a bonding jumper in an electrical system?
A) To connect the neutral and ground conductors
B) To ensure continuity between different metal parts
C) To isolate the electrical system from the earth
D) To increase the voltage supply to the circuit
Answer: B) To ensure continuity between different metal parts
,7. According to the NEC, how far should a lighting outlet be placed from the edge of
a bathtub?
A) 3 feet
B) 4 feet
C) 6 feet
D) 8 feet
Answer: C) 6 feet
8. What is the required minimum grounding conductor size for a 100-amp residential
service according to NEC?
A) 8 AWG
B) 6 AWG
C) 4 AWG
D) 2 AWG
Answer: B) 6 AWG
9. When installing a subpanel, what is the correct method for connecting the neutral
and ground wires?
A) Bond the neutral and ground wires in the subpanel
B) Separate the neutral and ground wires in the subpanel
C) Connect the neutral wire to the ground wire in the main panel
D) Connect the neutral and ground wires together at the meter
Answer: B) Separate the neutral and ground wires in the subpanel
10. What is the maximum allowable voltage drop for a feeder circuit according to
NEC guidelines?
, A) 2%
B) 4%
C) 6%
D) 8%
Answer: B) 4%
11. What is the minimum size conduit required for a group of 3 conductors of 12
AWG according to NEC?
A) 1/2 inch
B) 3/4 inch
C) 1 inch
D) 1 1/4 inch
Answer: A) 1/2 inch
12. In which of the following situations is a double-pole circuit breaker required?
A) For a 240-volt circuit
B) For a 120-volt circuit
C) For a 277-volt circuit
D) For a 480-volt circuit
Answer: A) For a 240-volt circuit
13. According to the NEC, which type of box is required for an outdoor location
exposed to weather?
A) Plastic box
B) Metal box with weatherproof cover
