Journeyman Electrician’s Exam Journeyman Electrician's Conductor Sizing and Ampacity 5

Question 1

What is the maximum voltage drop recommended by NEC 210.19(A) informational note for branch circuit conductors?

Accepted Answer

3%

Answer

NEC 210.19(A) informational note recommends a maximum voltage drop of 3% for branch circuits.

Question 2

A 12 AWG copper conductor is rated 20A at 60°C and 25A at 90°C. If the equipment termination is rated 60°C, what ampacity must be used?

Accepted Answer

20A, limited by the termination rating

Answer

The ampacity is limited to 20A because the termination is rated only 60°C, regardless of the conductor's higher insulation rating.

Question 3

Per NEC 310.15(B)(3)(a), what adjustment factor applies to conductors installed in conduit exposed to direct sunlight on a rooftop where the conduit is 7 inches above the roof surface?

Accepted Answer

Add 14°C

Answer

When conduit is between 3.5 and 12 inches above a rooftop, NEC adds 14°C to the ambient temperature for ampacity calculations.

Question 4

Two 500 kcmil conductors per phase are installed in parallel. Each 500 kcmil copper conductor at 75°C has 380A ampacity. What is the total ampacity for the parallel set?

Accepted Answer

760A

Answer

Parallel conductors add their individual ampacities: 380A × 2 = 760A total per phase.

Question 5

What is the minimum conductor size that may be used in parallel per NEC 310.10(H)(1)?

Accepted Answer

1/0 AWG

Answer

NEC 310.10(H)(1) requires each parallel conductor to be at least 1/0 AWG copper or 1/0 AWG aluminum.

Journeyman Electrician’s Exam Practice Test

Journeyman Electrician’s Exam Practice Test

Journeyman Electrician’s Exam Journeyman Electrician's Conductor Sizing and Ampacity 5