FREE E2 Wiring Methods and Materials Questions and Answers

Question 1

An inspector observes a 40-foot continuous run of 1-inch Electrical Metallic Tubing (EMT) installed exposed on a commercial warehouse wall. What are the maximum permitted spacing requirements for securing and supporting this raceway according to NEC Article 358?

Accepted Answer

Within 3 feet of each box and every 10 feet thereafter.

Answer

NEC 358.30(A) requires that EMT be securely fastened in place at least every 10 feet. Additionally, NEC 358.30(B) mandates that EMT must be securely fastened within 3 feet of each outlet box, junction box, device box, cabinet, or conduit body.

Question 2

According to NEC Table 310.15(C)(1), what is the required adjustment factor for the allowable ampacity of conductors when there are 8 current-carrying conductors installed in a single conduit?

Accepted Answer

70%

Answer

NEC Table 310.15(C)(1) provides adjustment factors for raceways or cables containing more than three current-carrying conductors. For 7 to 9 current-carrying conductors, the allowable ampacity of each conductor must be reduced to 70% of the value listed in the ampacity tables.

Question 3

When Type MC cable is installed through a field-punched hole in a steel stud in a commercial building, which of the following protection methods is required by the NEC?

Accepted Answer

A listed bushing or grommet must be installed in the opening.

Answer

NEC 300.4(B)(1) requires that where cables pass through holes in metal members, the cable must be protected by a listed bushing or listed grommet that is securely fastened in the opening to protect the cable from the sharp metal edges.

Question 4

In a commercial building, which of the following wiring methods is generally prohibited by NEC Article 358 for use where it would be subject to severe physical damage?

Accepted Answer

Electrical Metallic Tubing (EMT)

Answer

NEC 358.12(1) explicitly states that Electrical Metallic Tubing (EMT) shall not be used where, during installation or afterward, it will be subject to severe physical damage. RMC, IMC, and other heavier-walled conduits are designed for such environments.

Question 5

An inspector is performing a box fill calculation for a metal device box. According to NEC 314.16(B)(4), what volume allowance must be made for a single duplex receptacle mounted on a single yoke?

Accepted Answer

A double volume allowance based on the largest conductor connected to the device.

Answer

NEC 314.16(B)(4) requires a double volume allowance for each yoke or strap containing one or more devices. This allowance is calculated based on the cubic inch volume for the largest conductor connected to the device, as specified in Table 314.16(B).

(E2) E2 Commercial Electrical Inspector Practice Test

(E2) E2 Commercial Electrical Inspector Practice Test

FREE E2 Wiring Methods and Materials Questions and Answers