FREE TN LLE Conductors and Cables Questions and Answers

Question 1

An electrician installs five current-carrying THHN copper conductors in a single raceway in an area with an ambient temperature of 98°F. If each conductor is 8 AWG, what is its final allowable ampacity after applying all necessary correction factors?

Accepted Answer

36.96 A

Answer

First, find the starting ampacity for 8 AWG THHN copper wire from NEC Table 310.16 in the 90°C column, which is 55A. Next, determine the temperature correction factor from Table 310.15(B)(1) for 98°F (37°C), which is 0.96 for the 90°C column. Then, find the adjustment factor for five current-carrying conductors from Table 310.15(C)(1), which is 70% (or 0.70). Multiply the starting ampacity by both factors: 55A * 0.96 * 0.70 = 36.96 A.

Question 2

According to NEC Article 310, which of the following conductor types is suitable for use in a wet location?

Accepted Answer

THWN-2

Answer

NEC Table 310.104(A) lists the applications for various conductor insulations. THWN-2 is listed for use in dry, damp, and wet locations. THHN is primarily for dry and damp locations. FFH-2 (Fixture Wire) and TFFN (Fixture Wire) have more restricted uses and are not generally rated for wet locations in this context.

Question 3

An electrician is connecting a 10 AWG solid copper conductor to a standard screw terminal on a receptacle. Which of the following installation practices is required by the NEC?

Accepted Answer

The conductor must be wrapped in a clockwise direction around the screw.

Answer

NEC 110.14(A) requires that terminals be used according to the manufacturer's instructions. Standard practice, enforced by inspectors and integral to proper workmanship, dictates that conductors be wrapped clockwise around a screw terminal. This ensures that tightening the screw also tightens the wire loop, creating a secure connection. Wrapping counter-clockwise would cause the loop to open and loosen as the screw is tightened.

Question 4

When conductors are installed in parallel, which of the following is NOT an NEC requirement for each of the parallel conductors within a set?

Accepted Answer

They must have the same color insulation.

Answer

NEC 310.10(G) outlines the requirements for conductors in parallel. It mandates that they be the same length, made of the same material, have the same circular mil area, and have the same insulation type. However, it does not require them to have the same color insulation, as long as they are properly terminated and identified according to their function (e.g., ungrounded, grounded, grounding).

Question 5

What is the minimum size copper conductor permitted for general purpose branch circuits in residential, commercial, and industrial locations?

Accepted Answer

14 AWG

Answer

According to NEC 310.106(A), the smallest conductor permitted for branch circuits for general wiring is 14 AWG copper, except where other sections of the code permit smaller conductors for specific applications like fixture wire or low-voltage systems.

TN LLE - Tennessee Limited Licensed Electrician Practice Test

TN LLE - Tennessee Limited Licensed Electrician Practice Test

FREE TN LLE Conductors and Cables Questions and Answers