FREE Journeyman Electrician’s Conductor Sizing and Ampacity Questions and Answers

Question 1

An electrician is installing eight current-carrying 10 AWG THHN copper conductors in a single raceway in an area with an ambient temperature of 40°C.
The terminals on the equipment are rated for 75°C.
What is the final adjusted ampacity for each conductor?

Accepted Answer

22.75 A

Answer

30 A

Answer

28 A

Answer

17.5 A

Question 2

A commercial kitchen is installing a fixed electric cooking appliance with a nameplate rating of 22 kW at 240V, single-phase. The circuit will be run with Type NM-B cable. According to NEC Table 220.55, what is the minimum required ampacity for the branch-circuit conductors?

Accepted Answer

40A

Answer

80A

Answer

91.7A

Answer

50A

Question 3

What is the maximum allowable ampacity of a 12 AWG copper conductor with THHN insulation when used in a branch circuit that is not subject to any adjustment or correction factors, and connected to terminals rated for 75°C?

Accepted Answer

20A

Answer

15A

Answer

25A

Answer

30A

Question 4

Which of the following is required when sizing conductors for a continuous load, such as commercial office lighting that operates for more than three hours at a time?

Accepted Answer

The conductor ampacity must be at least 125% of the continuous load.

Answer

The conductor ampacity must be at least 80% of the continuous load.

Answer

The conductor ampacity must be calculated at 100% of the continuous load.

Answer

The conductor ampacity must be double the continuous load.

Question 5

An electrician bundles twelve 10 AWG THWN-2 copper current-carrying conductors in a single conduit for a continuous length of 36 inches. The ambient temperature is 30°C and the terminals are rated 90°C. What is the adjusted ampacity of each conductor?

Accepted Answer

20A

Answer

40A

Answer

28A

Answer

35A

Question 6

A feeder supplies a continuous lighting load of 80A and a non-continuous receptacle load of 50A. The terminals are rated for 75°C. What is the minimum required ampacity for the feeder conductors?

Accepted Answer

150A

Answer

130A

Answer

104A

Answer

162.5A