Free NEC Wiring and Protection 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?

Accepted Answer

10 AWG

Answer

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?

Accepted Answer

It requires both AFCI and GFCI protection.

Answer

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?

Accepted Answer

24 inches

Answer

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?

Accepted Answer

Flexible Metal Conduit (FMC)

Answer

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?

Accepted Answer

Both GFCI and AFCI protection

Answer

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.

NEC Practice Test

NEC Practice Test

Free NEC Wiring and Protection Questions and Answers