Free NEC Wiring and Protection Questions and Answers — Questions and Answers
Question 1: According to NEC 2023, what is the minimum size copper equipment grounding conductor (EGC) required for a 60-ampere branch circuit protected by an overcurrent device?
- 12 AWG
- 10 AWG (Correct answer)
- 8 AWG
- 6 AWG
Correct answer: 10 AWG
NEC Table 250.122 specifies the minimum size equipment grounding conductor for grounding raceways and equipment. For a circuit with a 60-ampere overcurrent device, the table requires a minimum of a 10 AWG copper conductor.
Question 2: A 125-volt, 15-ampere receptacle is being installed to serve a kitchen countertop in a new residential dwelling. Which of the following is true regarding its protection requirements?
- It requires only overcurrent protection.
- It requires only AFCI protection.
- It requires both AFCI and GFCI protection. (Correct answer)
- It does not require GFCI protection if it is more than 6 feet from the sink.
Correct answer: It requires both AFCI and GFCI protection.
NEC Section 210.12(A) requires AFCI protection for all branch circuits supplying outlets in dwelling unit kitchens. Additionally, NEC Section 210.8(A)(6) requires GFCI protection for all 125-volt through 250-volt receptacles installed to serve kitchen countertops. Therefore, both AFCI and GFCI protection are required.
Question 3: In a commercial building, a 480/277V, 3-phase, 4-wire, solidly grounded wye service is installed. What is the MINIMUM depth of cover required for Rigid Metal Conduit (RMC) installed under a parking lot?
- 6 inches
- 12 inches
- 18 inches
- 24 inches (Correct answer)
Correct answer: 24 inches
NEC Table 300.5, Column 3, specifies the minimum cover requirements for wiring methods. For Rigid Metal Conduit (RMC) installed under areas subject to heavy vehicular traffic, such as parking lots, a minimum cover of 24 inches is required.
Question 4: Which of the following wiring methods is NOT permitted to be used for the ungrounded service-entrance conductors?
- Rigid Metal Conduit (RMC)
- Electrical Metallic Tubing (EMT)
- Type SE Cable
- Flexible Metal Conduit (FMC) (Correct answer)
Correct answer: Flexible Metal Conduit (FMC)
According to NEC 230.43, Flexible Metal Conduit (FMC) is not listed as a permitted wiring method for service-entrance conductors unless it is used as part of a listed service-entrance cable assembly or is used to connect service-entrance conductors to service-entrance equipment where flexibility is required.
Question 5: An electrician is installing a new branch circuit in a dwelling unit laundry area. The circuit will supply a 120-volt receptacle for a washing machine. According to the 2023 NEC, what type of protection is required for this receptacle?
- AFCI protection only
- Overcurrent protection only
- GFCI protection only
- Both GFCI and AFCI protection (Correct answer)
Correct answer: Both GFCI and AFCI protection
NEC 210.8(A)(10) requires GFCI protection for all 125-volt through 250-volt receptacles installed in laundry areas. Additionally, NEC 210.12(A) requires AFCI protection for branch circuits supplying outlets or devices in dwelling unit laundry areas. Therefore, both types of protection are mandatory.
Question 6: When conductors are installed in a conduit that is exposed to direct sunlight on a rooftop, their ampacity must be adjusted for ambient temperature. If the ambient temperature is 30°C (86°F), what temperature adder must be applied to the ambient temperature for conduits located 1/2 inch above the rooftop?
- 17°C (30°F) (Correct answer)
- 22°C (40°F)
- 33°C (60°F)
- 25°C (45°F)
Correct answer: 17°C (30°F)
NEC Table 310.15(B)(2)(c) provides temperature adders for circular raceways exposed to sunlight on or above rooftops. For a conduit with its bottom less than 1/2 inch from the roof, a temperature adder of 33°C (60°F) is required. However, for a conduit installed with a distance between 1/2 inch and 12 inches from the roof, the temperature adder is 17°C (30°F).
Free NEC Wiring and Protection Questions and Answers
According to NEC 2023, what is the minimum size copper equipment grounding conductor (EGC) required for a 60-ampere branch circuit protected by an overcurrent device?