Journeyman Electrician’s Exam Journeyman Electrician's Conductor Sizing and Ampacity 2

Question 1

A 120/240V single-phase service uses 2 AWG copper conductors. What is the standard ampacity of 2 AWG copper at 75°C per NEC Table 310.15(B)(16)?

Accepted Answer

115A

Answer

2 AWG copper conductors have a standard ampacity of 115A at 75°C per NEC Table 310.15(B)(16).

Question 2

Three current-carrying conductors are bundled in a conduit. According to NEC 310.15(C)(1), what adjustment factor applies?

Accepted Answer

No adjustment needed

Answer

NEC 310.15(C)(1) requires no adjustment factor for 3 or fewer current-carrying conductors.

Question 3

Which conductor material has higher conductivity, requiring a smaller gauge for equivalent ampacity?

Accepted Answer

Copper

Answer

Copper has higher conductivity than aluminum, so it carries more current at the same wire gauge.

Question 4

A feeder supplies a continuous load of 80A. What is the minimum conductor ampacity required before applying breaker sizing?

Accepted Answer

100A

Answer

Conductors for continuous loads must be sized at 125% of the load (80A × 1.25 = 100A) per NEC 215.2.

Question 5

What NEC table is used to find the ampacity of conductors 0-2000V with not more than 3 current-carrying conductors in a raceway?

Accepted Answer

Table 310.15(B)(16)

Answer

NEC Table 310.15(B)(16) provides ampacity values for conductors up to 2000V with no more than 3 current-carrying conductors.

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