Free TN LLE Raceways and Boxes Questions and Answers

Question 1

An electrician is installing a run of 1/2-inch Electrical Metallic Tubing (EMT) on the surface of a wall. According to NEC Article 358, what is the maximum permitted spacing between supports for this raceway?

Accepted Answer

10 feet

Answer

NEC 358.30(A) states that EMT shall be securely fastened in place at least every 3 m (10 ft). Additionally, a support is required within 3 feet of each termination point like a box or conduit body.

Question 2

An electrician installs a junction box with raceways containing 4 AWG conductors entering and leaving on opposite walls for a straight pull. According to NEC 314.28(A)(1), what is the minimum required length of this pull box?

Accepted Answer

Eight times the trade size of the largest raceway.

Answer

NEC 314.28(A)(1) specifies that for straight pulls involving conductors 4 AWG or larger, the length of the box must be at least eight times the trade size (diameter) of the largest raceway entering the box.

Question 3

What is the maximum total degrees of bends permitted in a single run of conduit between two pull points (e.g., from one junction box to another)?

Accepted Answer

360 degrees

Answer

NEC articles for most raceway types, such as 344.26 for RMC and 358.26 for EMT, state that there shall not be more than the equivalent of four quarter bends (360 degrees total) between pull points. This rule prevents damage to conductor insulation during pulling.

Question 4

An electrician is calculating the required size of a device box that will contain one duplex receptacle, two 12/2 non-metallic sheathed cables, and has no internal clamps. How many conductor volumes must be counted for the duplex receptacle itself?

Accepted Answer

Two, based on the largest conductor connected to it.

Answer

According to NEC 314.16(B)(4), each yoke or strap containing one or more devices (like a switch or receptacle) requires a double volume allowance based on the size of the largest conductor connected to the device.

Question 5

When installing more than two current-carrying conductors in a single raceway, what is the maximum allowable percentage of the raceway's interior cross-sectional area that can be filled?

Accepted Answer

40%

Answer

NEC Chapter 9, Table 1 specifies the allowable fill percentages for raceways. For one conductor, the limit is 53%; for two conductors, it's 31%; and for more than two conductors, the maximum fill is 40%.

TN LLE - Tennessee Limited Licensed Electrician Practice Test

TN LLE - Tennessee Limited Licensed Electrician Practice Test

Free TN LLE Raceways and Boxes Questions and Answers