FREE E2 Conductor Ampacity and Derating Questions and Answers

Question 1

What is the allowable ampacity of a 3 AWG THWN copper conductor operating at 75°C?

Accepted Answer

100 A

Answer

85 A

Answer

115 A

Answer

110 A

Question 2

If ten 12 AWG THHN copper current-carrying conductors are installed in a single conduit, what adjustment factor must be applied to their ampacity?

Accepted Answer

50%

Answer

80%

Answer

70%

Answer

60%

Question 3

A 2/0 AWG THWN copper conductor is to be installed in an area with an ambient temperature of 110°F (43°C). What is its approximate allowable ampacity?

Accepted Answer

144 A

Answer

175 A

Answer

158 A

Answer

123 A

Question 4

Four 4 AWG THHN copper current-carrying conductors are run in a conduit on a rooftop where the ambient temperature is 125°F (52°C). What is the allowable ampacity of each conductor?

Accepted Answer

62.3 A

Answer

76.0 A

Answer

66.5 A

Answer

54.4 A

Question 5

Which conductor is NOT considered a current-carrying conductor for the purposes of applying adjustment factors from Table 310.15(C)(1)?

Accepted Answer

A neutral conductor of a balanced 3-phase, 4-wire, wye-connected system.

Answer

An ungrounded 'hot' conductor in a single-phase circuit.

Answer

An equipment grounding conductor.

Answer

The neutral conductor of a 120/240V single-phase system.

Question 6

A commercial air conditioning unit has a nameplate rating of 38A. The circuit will be run with THWN copper conductors. What is the minimum size conductor required?

Accepted Answer

8 AWG

Answer

10 AWG

Answer

6 AWG

Answer

4 AWG