Fundamentals of Code Calculations Practice Test 2026 - Free Code Calculation Practice Questions and Study Guide

To determine the minimum size copper wire required for a 120-volt, single-phase circuit supplying a 30-ampere load over a distance of 205 feet, it is essential to consider both the current-carrying capacity of the wire and the voltage drop that can occur over the distance.

When calculating the wire size, the American Wire Gauge (AWG) system is used, which designates sizes in a way that smaller numbers indicate larger diameters. For a given current load, a specific wire size is required to safely carry the current without overheating.

In this scenario, the load is 30 amperes, and the distance is significant enough (205 feet) that voltage drop must be considered. The National Electrical Code (NEC) recommends maintaining a voltage drop of no more than 3% for branch circuits.

For copper wire, the appropriate size to ensure that the wire can safely carry the load and maintain an acceptable voltage drop is determined through standard tables that list the ampacity of different wire sizes along with adjustments for distance. The 3 AWG copper wire can typically handle 30 amperes with adequate consideration for voltage drop over 205 feet, making it suitable for this circuit.

This choice effectively addresses both the current requirements and