Journeyman Electrician Practice Exam 2025 - Free Electrician Practice Questions and Study Guide

To determine the minimum size copper grounding electrode conductor required when using four parallel sets of size 500 kcmil aluminum conductors, it is essential to refer to the National Electrical Code (NEC) guidelines for grounding conductors.

The NEC Table 250.66 outlines the minimum conductor size for the grounding electrode conductor, specifically based on the size of the largest ungrounded conductors. In this scenario, since we are using four parallel sets of 500 kcmil aluminum conductors, we first need to identify the equivalent size of copper for grounding purposes.

According to the NEC, when conducting calculations for grounding electrode conductors, the size for aluminum conductors must be adjusted. For 500 kcmil aluminum conductors, the NEC specifies that a 500 kcmil aluminum conductor is equivalent to a 250 kcmil copper conductor when determining the size of the grounding electrode conductor.

Referring to the table, the grounding electrode conductor for a 250 kcmil copper conductor would correspond to a minimum size of 4 AWG for copper. This is derived from the requirement that for a copper grounding conductor, the size must be at least 4 AWG when derived from the largest conductor in the installations (in this case